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691 Cards in this Set
- Front
- Back
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What does the term organic imply?
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It implies that the molecule has some carbon.
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On average, how large are cells?
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About 5-10 um (I/1,000 of a millimeter) in size.
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The cell membrane is composed of 2 layers of phospholipid molecules, it is called a phospholipid bilayer. true/False
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True. It is a combination of phosphate and fatty acids. There is also cholesterol contained within.
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What is meant by a trransmembrane protein?
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They span the membrane and have ends in the external tissue fluid and internal cytosol. substance passage is regulated because of this.
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What are the functions of cell receptors?
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These specialized receptor cells of protein recognize chemical messengers from other cells and substances (endocrine glands).
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What is colloid?
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Cytosol is mostly water with additional dissolved and suspended molecules, the combination of which is referred to as colloid.
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What forms the cytoskeleton?
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Microfilaments and microtubules are composed of proteins and extend throughout the cytosol. These structures form the cytoskeleton.
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What are endoplasmic reticulum proteins?
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This structure is bound by membranes. Its function is to move materials around inside the cell, intracellular translocation.
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What is rough endoplasmic reticulum?
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If an area of ER is associated with ribosomes, it is referred to as rough ER. Without ribosomes it is called smooth ER.
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What is the function of Ribosomes?
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They receive genetic information and instructions from the DNA in the nucleus of the cell. This info is then transferred to molecules of RNA which then string together long chains of amino acids to form polypeptides and proteins.
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What is the function of the Golgi complex?
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This structure is an arrangement of membranes which are responsible for the export of products from the cell.
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What do mitochondria look like?
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They are usually sausage shaped and possess an outer membrane and a highly enfolded inner membrane. This inner membrane provides a large surface area for the location of enzymes responsible for energy generation within the cell.
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What is the basic toxic mechanism of cyanide?
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It is a very fast acting poison because it stops the process of energy production in mitochondria.
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Does mitochondria possess any DNA?
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Yes. Interestingly, mitochondrial DNA is passed on only through the maternal line, from mothers to daughters or to sons.
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What do lysosomes do?
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These organelles are surrounded by the typical membrane bilayer and have a variety of digestive enzymes such as lysozyme. They are formed by breaking away from the Golgi apparatus and dispersed throughout the cytosol. They are used for intracellular digestion.
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How do hydrolyzing enzymes function?
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They split large molecules up by the addition of hydrogen and oxygen.
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Lysosomes are essential for the process of phagocytosis. True/False
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True. Unwanted cellular organelles and biomolecules are digested by lysosomal enzymes in the process of autophagy. They may also burst to digest a whole cell which is unwanted by the body in a form of cell suicide called apoptosis.
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What are peroxisomes?
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These substances contain enzymes including H2O2, which function by oxidizing toxic substances. App. half of the alcohol a person drinks is detoxified by peroxisomes in liver cells.
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What do chromosomes contain?
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They contain the genes which are the genetic information responsible for making and controlling the cell. All human cells contain 46 of these bodies. They are arranged in 23 pairs.
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What are genes?
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Genes are part of the chromosomes and are composed of DNA strands.
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What is a nucleolus?
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A nucleolus is a cluster of DNA, RNA and protein within the nucleus.
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What are the two forms of cell division?
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Mitosis and meiosis.
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What is Mitosis?
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Each gene is copied to make an exact copy of the original. here, one complete set of chromosomes migrates to each end of the cell. This parent cell then divides into 2 daughter cells each containing 46 chromosomes.
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Give an example of when Mitosis occurs?
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It occurs when the body grows from a zygote, which is a single fertilized cell, into a baby. It also generates new tissue in wound healing.
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What is Meiosis?
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This division is only used in the production of gametes which are the male sperm and the female ova.
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What is the purpose of meiotic division?
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To prevent the increase in chromosome number, the sperm and ovum are produced by meiosis which is a reduction cell division.
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What happens during meiosis?
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The daughter cell,(always a sperm or an ovum) only receives one from each pair of chromosomes, leaving each sperm or ovum with 23 chromosomes. The zygote receives 23 chromosomes from the ovum and 23 from the sperm, to give it a total (diploid) of 46 chromosomes.
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What is the pH of HCl acid?
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It is about 1. Ammonium hydroxide has a pH of about 14.
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Why do enzymes usually require specific conditions to function?
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Enzymes are complex proteins formed into a particular shape. They possess complex molecular shapes.
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What are the four types of tissue in the body?
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Epithelial
Connective Muscle Nervous |
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What are the four forms of simple epithelium?
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Squamous
Cuboidal Columnar Ciliated |
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Is there a reason that the mouth lined with stratified squamous epithelium?
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During the relative trauma of chewing food, some of the surface cells may be sloughed away from the epithelium without disturbing the overall integrity.
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Connective tissue generally has fewer cells than epithelial tissue. True/False
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True. Connective tissue is stronger and has more elastic components.
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What is white fibrous tissue?
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It is a strong connector composed of bundles of collagen fibres with a few fibroblasts included in the tissue.
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What are fibroblasts?
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Fibroblasts are cells which produce collagen protein.
The spaces between the cells and fibers in connective tissue are filled with ground substance called matrix. |
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Is it true that white fibrous tissue is responsible for holding the body together?
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Yes. They also keep the bones in the correct positions relative to each other.
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Do fibroblasts produce elastic fibers?
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Yes. Elastic fibers are made up of elastin.
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Where is elastin found?
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Elastin is found in structures such as blood vessels, lungs, epiglottis and ear lobes.
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Where is loose connective tissue found?
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It is found in areas where tensile strength is needed. It is found beneath the skin, and between muscle fibers. Some call this areolar tissue.
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Where do individual cells store fat?
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It is stored in a large central area called a vacuole.
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Where is articular cartilage found?
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It lines joint surfaces to give a smooth and hard low friction surface between bones.
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What is osmolarity?
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It is the power of a solution to osmotically attract water through a semi-permeable membrane.
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In an average adult body, how much water is there completely?
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There is between 35 and 40 litres of water. This comprises about 60% of body weight. Most water is found inside the cells(25 litres). This is the intracellular compartment. The rest is located outside the cells (extracellular fluid).
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It is the large protein molecules in blood that give it its osmolarity? True/False
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True.
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Sperm prefer temperatures around 35C. True/False
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True.
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What is cardiac massage?
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The heart is compressed between the thoracic vertebral column and the sternum. As the pressure in the heart increases, blood will open the valves and be forced through the heart and out into the aorta and pulmonary aorta.
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What is atrial kick?
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This is represented by the final filling of the ventricles by atrial contraction. Both atria contract almost simultaneously.
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At the start of ventricular contraction, a ventricle will contain how much blood?
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It will contain about 120ml of blood. after contraction however, 70mls of blood will be ejected. The other 50ml will remain in the ventricle until the next cardiac cycle.
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During the cardiac cycle, how long app. does ventricular systole take?
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About 0.3 seconds, and vent. diastole takes about 0.5 sec. In exercise these values usually decrease.
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What is the difference of blood pressure in the both the systemic and pulmonary circulation?
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In the systemic, as it exits the heart is about 120/70. In the pulmonary circulation, it is about 25/8mm/Hg
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What is the significance of the P wave?
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This represents depolarization of the atrial myocardium. There is a firing of the SA node.
The QRS complex is the depolarization of the ventricular myocardium. |
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Is the T wave associated with a muscular contraction?
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No. It arises as the ventricular muscle repolarized to an electrically resting state.
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How is heart rate measured?
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It is HR= CO X SV
CO= output SV = stroke volume |
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How is blood pressure determined?
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By the cardiac output multiplied by the peripheral resistance.
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Capillaries are the only part of the vascular system where exchange takes place. True/False
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True. This is true because they are only one squamous cell thick.
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What is a capillary bed?
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This is a system of capillaries perfusing a particular area of tissue. Finger nail beds are pink because of the color of the blood passing through them.
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It is believed that that the total area of capillary wall in an adult is about 6,000 sq. meters. True/False
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True.
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At the venous end of a capillary, why is blood pressure lower?
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Thisis so because the blood is nearing the lower pressure venous system. The oncotic pressure however, does not change.
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What are perforator veins?
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Between the superficial and the deep venous systems are small veins called perforator veins, so called because they perforate the muscle fascia.
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What is a portal vein?
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A portal vein is one which does not drain into a larger vein, but ends in capillaries.
There is a portal system between the hypothalamus and the anterior pituitary to carry hypothalamic releasing hormones. As blood is passing from one area to another it is not diluted in the entire blood volume. |
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What is the heaptic portal system?
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Blood draining from the stomach, small and large intestine is collected together into this single vessel. The result of this is most of the blood drained from the gut passes directly into the liver. Only once it has passed through the liverdoes it enter the inferior vena cava via the hepatic veins.
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What is the main reason for the hepatic vein?
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It permits the liver to break down bacterial metabolic toxins, genertated in the lumen of the gut, before they enter the systemic circulation.
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Lymphatic capillaries are highly permeable. True/False
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True. They can absorb excess tissue fluid and infecting bacteria as well as proteins. Endothelial cells which compose the lymphatic capillary walls are separated by pores. These allow fluid to enter.
These cells also overlap to form valves. |
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What is the white pulp of the spleen?
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It is composed of lymphatic tissue and is full of lymphocytes and macrophages. These will destroy any bacteria that has entered the blood. The large numbers of WBCs in the spleen means that infections can often be eliminated before they have time to be established.
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What is the function of red pulp?
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The red pulp is more related to the RBCs. It contains blood filled sopaces called sinusoids. Like the white pulp acts as a reservoir for WBCs, the red pulp holds a reserve of red cells. Many old RBCs will be also be destroyed here and recycled appropriately.
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Regarding the spleen, what happens if there is a hemorrhage?
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The spleen can contract and transfer blood from the sinusoids into the systemic circulation.
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When people refer to tonsils, which tissue are they referring to?
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It is the tonsils in the oropharanyx that people usually mean when referring to tonsils. These are the palatine tonsils.
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What happens if heparin is added to a sample of blood?
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The sample is centrifuged, and all of the cells will be forced to the bottom of the tube while the plasma remains floating on top.
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At about 6 months of age how many mls of blood will a baby have?
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About 500ml. At 2 years of age this will rise to about a litre. At ten years they may have about 2 liters and a 12 year old about 3 litres.
Most adults could usually lose (transfusion) about 500 cc without untoward effects. This is a unit of blood. |
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What are the three main plasma proteins?
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Albumin, Globulin and fibrinogen. These are large molecules and their presence is vital to generate a plasma osmotic potential. Albumin is the most common plasma protein and generates most of the osmotic potential.
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Most of the CO2 transported by the blood is carried by the plasma. True/False
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True. Plasma also transpprts endocrine hormones from glands to their target tissues.
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Is blood more alkaline or acidic?
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It is slightly alkaline. Arterial blood has a pH of 7.35-7.45, but venous blood is slightly more acidic with a pH of about 7.35. This is caused by increased loads of CO2 carried in the venous blood, some of which is carried as carbonic acid.
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Are RBCs concave for a reason?
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Yes. This shape provides a large surface area for gaseous exchange and also gives the cell flexibility.
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How large are RBCs app. in diameter?
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They are about 7 micrometers in diameter.
Every cubic millimeter of blood has about 5 million RBCs. |
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A single hemoglobin molecule can accomodate how many oxygens?
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It can form a loose bond with 4 O2 molecules. The Hg molecule is based on 4 atoms of iron. without iron, O2 cannot be synthesized.
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Vitamin B12 and folic acid are also essential for the normal maturation of RBCs. True/False
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True.
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Why are mature RBCs considered somewhat unique?
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They have no nucleus which will allow more space for carrying hemoglobin, but also limits the lifespan of the RBC to about 17 weeks.
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The colored pigment from the hemoglobin is converted to what?
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It is converted into a bile pigment called bilirubin, which is taken up by the liver and excreted into the small intestine in bile.
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Each cubic millimeter of blood contains how many WBCs?
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It contains about 7,000 leukocytes.
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How large are eosinophils?
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They are about 13-15 um. Their cytoplasmic granules are actually larger than those found in neutrophils. They represent about 2-4 % of leukocytes in blood.
The nucleus has 2 lobes joined by a thin thread. |
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What do eosinophils do?
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They halp the body fight infections of protozoa, and larger parasites. Eosinophils can attach themselves to the body of the parasite using adhesion molecules.
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Are eosinophils attracted to regions in the body that are experiencing an allergic reaction?
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Yes. An example would be the bronchioles in people with asthma. They may neutralize some of the inflammation causing substances, such as histamines which are involved in the generation of allergic responses.
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Basophils comprise app. what percentage of leukocytes?
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0.5%. The nucleus is regular lobed, but is often hard to see through the large abundant granules in the cytoplasm.
The granules contain histamine, heparin and bradykinin. |
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What is a mast cell?
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Most basophils enter the tissues where they remain localized. In the tissues they are referred to as mast cells and their main function is to facilitate an inflammatory reaction in response to any insult of the tissue.
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Which cell sare considered the the most common form of lymphocytes?
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Agranulocytes.They comprise about 20-25% of circulating leukocytes. They may be large or small.
Large lymphocytes are the natural killer cells (NK) and are able to kill body cells infected with viruses. |
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What are the 2 main forms of small lymphocytes?
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B cells
T cells |
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What are the three forms of T cells?
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T helper cells
T cytotoxic cells T suppressor cells T helper cells assist B cell cells in the production of antibodies. |
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What are monocytes?
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Monocytes are large phagocytic cells. They may be as large as 20um in diameter.
The nucleus is large ans is usually kidney shaped. |
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Can monocytes migrate through capillary walls/
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Yes. This is done via ameboid movement(diapedesis) so they may live in organs or tissues. At this stage, they become macrophages. Purpose is to destroy foreign protein entities.
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How long do macrophages live?
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They may live for years before being required to perform an immune function. They act as the first line of defense for body tissues.
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What happens if infection is detected in a tissue?
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The macrophages will release a chemical messenger called a cytokine. This cytokine will circulate to the bone marrow where it will increase the release of neutrophils to fight the infection.
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What else are macrophages capable of?
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They can produce pyrogens which act on the hypothalamus to increase body temperature during infection.
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Can rhesus positive patients receive Rhesus negative blood?
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Yes. The negative red cells have no antigens.
Once the Rhesus factor is taken into consideration, it means that O negative is the universal donor and AB positive the universal recipient. |
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What is the D factor?
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The Rhesus factor is sometimes called the D factor. This is the most active component of the Rhesus factor antigen is termed the D factor.
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In hemolytic disease of the newborn, what is the anti D injection?
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This is given to the mother after the birth of every baby. These injected D antibodies quickly destroy any RH positive baby cells in the mothers blood.
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What are the three categories of hemostasis/
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Vascular spasm
Platelet plugging Coagulation cascade |
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Can low temperatures affect vascular spasm?
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Yes. Low enough temperatures can limit the amount of bleeding, depending on the wound.
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When does the process of clotting start?
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It starts when factor X11, (Hageman factor) comes in contact with collagen in the damaged wall of a blood vessel.
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What is factor X11?
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It is a plasma protein which is normally present in plasma, but in an inactive form. It is the contact of collagen which activates factor X11 causing it to function as an enzyme.
Once activated, it will in turn activate further factors which eventually cause the inactive plasma protein called prothrombin to be broken down into thrombin, which is much smaller. |
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Factors derived from platelets and calcium ions are required for some of the steps in the coagulation process. True/False
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True. Vitamin k is necessary for the formation of prothrombin and fibrinogen, This explains why patients with liver failure or Vit. K deficiency may suffer from hemorrhagic conditions.
Warfarin inhibits vitamin K. |
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If a patient is systemically hypothermic, the blood will not clot normally. True/False
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True. This will result in longer bleeding times.
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What is plasminogen?
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Damaged tissues and vascular endothelium release a substance called tissue plasminogen factor or activator. Over several days, this will convert the trapped plasminogen into plasmin.
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What is the function of plasmin?
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Plasmin acts as a protein digesting (proteolytic) enzyme which breaks down the fibrin threads and so dissolves the clot.
Plasmin is occasionally called fibrinolysin. |
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What is the pharynx/
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This is a passage which connects the back of the nose and mouth with the trachea and esophagus.
It has three sections. Nasopharynx oropharynx Laryngopharynx. |
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If we vibrate the vocal cords at 261 hertz cycles per second this will produce a musical middle C. True/False
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True.
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Pulmonary cilia can cause can cause the mucus to move at a rate of 1 cm per minute. True/False
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True.
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What ensures that the trachea remains patent?
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The walls contain rings of cartilage which are rigid to prevent collapse.
Thje first ring of cartilage is a complete ring and is termed the cricoid cartilage. All of the lower rings are incomplete to allow the smooth passage of food down the esophagus which is behind the trachea. |
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Are the right and left primary bronchi structurally identical?
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No.The right bronchus is almost continuous with the trachea in more or less a straight line.
The left bronchus branches away from the trachea at a greater angle into the left lung. Foreign bodies usually enter the right primary bronchus. |
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Why are the tertiary bronchi also called the segmental bronchi?
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This is so because one enters each bronchopulmonary segment of a lobe. Each lung has a total of ten segments with ten corresponding segmental bronchi.
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As the bronchial tree continues to divide, the rings of cartilage are lost. True/False
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True. After 12-16 divisions the diameters of the airways are reduced to 1 mm or less and the tubes are referred to as bronchioles. Some cilia is still found here.
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The surface area of alveoli have what type of cells/
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Alveoli have thin walls with 90% of the surface area being composed of squamous cells.
The remaining 10% of the alveolar wall is composed of septal cells which secrete surfactant. |
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What is the function of surfactant?
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It reduces surface tension of the water which moistens internal surfaces of the air sacs.
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What is Respiratory distress syndrome?
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Premature babies often lack surfactant and this leads to the disorder called respiratory distress syndrome. (RDS)
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Why are the alveolar sacs folded into structures which resemble hollow bunches of grapes/
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This infolding increases the respiratory surface area to about 143 square meters in total.
There are about 300 million alveoli in the two lungs. |
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The left lung has how many lobes/
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It is composed of 2 lobes, each of which is, composed of five segments. These are bronchopulmonary segments.
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The right lobe has how many lobes?
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It has three lobes. The superior has three segments, the middle , two, and the inferior five.
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Do lung lobes have a specific role/
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Yes.They may be important for compartmentalizing infections.
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What artery supplies each segment of the lung?
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It is supplied with blood via a pulmonary segmental artery and drained by a segmental vein.
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Like the bronchial tree, the arterial and venous pulmonary vessels also form a fractal pattern. True/False
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True. A fractal arrangement ensures all areas of the lungs receive an equal supply of blood and are equally drained.
There are three superimposed fractal trees in the lungs; bronchial, arterial and venous. |
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In inspiration, when air moves into the lungs, the process is one of negative pressure ventilation. True/False
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TRue. In contrast, in artificial ventilation when air is actively blown into the lungs, this would be positive pressure ventilation.
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Why does the visceral pleural membrane expand on ispiration?
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This is because of the suction of the visceral pleural membrane onto the parietal pleural membrane. Should any air get into the potential pleural space(between visceral and parietal), the negative pressure that exists here would be lost.
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What is pneumothorax?
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In the case of a stab wound, movement of the parietal pleural membrane would no longer result in movement of the visceral pleural membrane and the lung would collapse.
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Should a pneumothorax occur, how serious is this event?
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It is serious, but not necessarily fatal. The two lungs are each surrounded by a separate visceral and parietal pleural membrane. Only one lung is likely to collapse.
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During normal breathing, how much air moves in and out of the lungs?
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About 500ml. This is called tidal volume. This will increase during exercise. The minute volume is calculated by multiplying the tidal volume by the number of breaths per minute. (500 X 12(normal breaths per minute) would be about 6,000ml.
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What is dead air space, or anatomical dead space?
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During inhalation, not all of the air reaches the respiratory surface. About 150ml of air is left in the nose, pharynx, larynx and bronchial passages. So, about 350 ml of fresh atmospheric air reaches the lungs as a result of each inspiration.
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What is inspiratory reserve volume?
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This is the amount of air that one can forcefilly inspire after a normal inspiration. It can total about 3100ml.
The expiratory reserve is about 1200 ml. Even with full strained expiration, there will always be at least one litre of air left in the lungs. This is the residual volume. |
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What is vital capacity?
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The combination of the expiratory reserve volume and the respiratory reserve is the vital capacity.
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What is normally considered the total lung capacity?
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It is about 6 litres.
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How is perfusion of blood through the lungs achieved?
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It is the result of the pumping effect of the right ventricle. This generates a systolic pulmonary blood pressure of about 25mm/Hg, and a diastolic of about 8mm/Hg.
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How is the blood able to maximize its O2 uptake?
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The blood is able to absorb as it passes through the lungs, blood needs to pass through the segments of the lungs where the alveoli are most oxygenated.
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What happens if the levels of gaseous O2 are reduced for any reason?
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There is little value in distributing little blood there as there is not much O2 to be obtained. To reduce the blood supply to poorly oxygenated areas of the lung the smaller pulmonary arteries and arterioles constrict. More blood is left over to perfuse well oxygenated areas of the lungs. (V/Q ratio)
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The diffusional distance between the air and blood is small to allow gaseous exchange. True/False
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True. Each alveolus is about 0.2 mm in diameter.
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Under normal conditions, what is considered a normal O2 saturation level when monitored?
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It should be about 98%-99% saturated.
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List three ways how CO2 is carried from tissues to the lungs?
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1.About 7% of the total CO2 is simply carried in solution after dissolving into the plasma.
2. Another 23% combines with Hb and is transported in RBCs. 3. About 70% forms HCO3 ions in combination with water in the plasma. (In the lungs these ions dissociate back into CO2 which then diffuses into the alveoli. |
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In reference to the above answer, a small amount is also transferred in the form of carbonic acid (H2CO3). True/False
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True. This explains why blood pH reduces if there is CO2 retention.
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What is atmospheric air a mixture of?
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It is a mixture of about 21% O2, 78% N2, 0.04% CO2 and several other trace gases. Argon, helium and neon also exist in minute quantities.
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In general, expired air has about 16% O2. True/False
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True. This is the justification for mouth to mouth resuscitation.
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What is the average distance between the blood and air in the alveoli?
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it is about 0.6 um.
O2 first diffuses into the fluid and surfactant layer then through the alveolar epithelium, interstitial space, capillary endothelium and then into RBCs. |
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C3, C4 and C5, keep the diaphragm alive. True/False
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True.
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Intercostal nerves leave the spinal cord via thoracic nerve roots to stimulate the intercostal muscles. True/False
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True. When the inspiratory impulses generated stop, the lungs and the respiratory muscles passively recoil causing expiration.
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Decreased pH of the blood may stimulate respiration. True/false
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True. This is seen in the air hunger characteristic of ketoacidosis in poorly managed diabetes mellitus.
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Nerve fibers from the motor cortex pass through the brain in a pathway called the internal capsule. true/False
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True. Most of the descending motor fibers cross over to the opposite side of the body at the level of the lower brain stem, before passing down the spinal cord.
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All of the motor neurons leave the spinal cord from the front. True/False
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True. The pathway they take is referred to as the anterior nerve root.
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What are neurofibral nodes?
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On a myelinated nerve there are small gaps between the Schwann cells called the neurofibral nodes. These were called the Nodes of Ranvier.
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What does myelin do?
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It increases the speed of a nerve impulse as it passes along the fiber. They are protective, and helps with their nourishment.
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if an atom loses an electron, it loses one of its negative charges. True/False
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True. This means that there is one more positive charge than a negative charge. this gives the atom an overall charge of plus one.
When an atom has an electrical charge it is no longer referred to as an atom but an ion. |
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Regarding neuronal transmission, if there are more negative ions inside the cell with relatively more positive ions outside, the overall charge will also be negative on the inside and positive on the outside. True/False
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True. This state is often called the resting potential. No nerve impulse is passing through the nerve at this moment.
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In reference to question 147, why is the cell considered polarized?
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Because in this situation there is a negative pole inside, and a positive pole on the outside.
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What happens when an impulse passes along the cell membrane?
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The result is the inside becomes positive and the outside negative. this is called depolarization.
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Why do myelinated fibers transmit the impulse very quickly?
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This is the case because the impulse does not need to travel along the full length of the fiber but is able to bounce from one neurofibral node to the next. this is called "salutatory transmission".
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How fast can an impulse travel in an unmyelinated fiber?
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Some may send an impulse as low as 0.5 meters a second.
Myelinated fibers may discharge at over 100 meters/sec. |
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What is a synapse?
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These are very small gaps between individual nerve cells and between motor neurons and muscles. these are synaptic gaps. This gap is a physical space and the electrical nerve impulse is unable to jump across. this limits the propagation of an impulse around the nervous system.
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What is a synaptic end bulb?
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Just before the gap, the presynaptic neurone widens out into a structure called the synaptic end bulb.
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What do these synaptic end bulbs contain?
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They contain mitochondria to provide energy for the function of the synapse. the bulb also contains vesicles of chemical transmitters ex. acetylcholine) which have been previously synthesized by the neurone.
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What happens when a nerve impulse arrives in the synaptic end bulb?
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It causes some secretory vesicles to fuse with the presynaptic membrane releasing a certain chemical transmitter into the gap. These transmitter molecules will eventually bind onto specific receptor sites on the post- synaptic membrane.
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What is GABA?
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Gamma-aminobutyric acid. This inhibits the activity of many neurons. if the levels of GABA are increased, the individual feels relaxed and at ease. Anti-anxiety drugs increase the activity of GABA,.
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What is Dopamine?
|
This substance is important for normal control of movement. When its secretion is deficient, Parkinson's disease may result.
In other areas of the brain, dopamine causes pleasure. In fact, their levels may be increased by drugs, such as alcohol, and even cocaine. |
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How do some antidepressants work?
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Some work by increasing the amounts of serotonin in the synaptic gaps. this is done by inhibiting the presynaptic reuptake.
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What are endorphins?
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These are transmitter molecules which can resuce pain. Morphine is able to activate endorphin receptor sites.
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Why are withdrawal symptoms common with the stoppage of addictive substances?
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When some chemical transmitters are taken artificially, the body responds by producing less of its own.
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What is the difference between white and grey matter in the brain?
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Grey matter is mostly nerve cells, and white matter is mostly nerve fibers.
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What are neuroglia?
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Often referred to as glia, this describes the tissues of the nervous system which are not neurons.
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Where are Schwann cells found?
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In the PNS the myelin sheath surrounding nerve fibers is composed of a form of neuroglial cells called Schwann cells.
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What are the 4 types of neuroglial cells found in the CNS?
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Oligodendrocytes
Microglia Ependymal cells Astrocytes |
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What do astrocytes do?
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They provide physical and nutrional support to neurons. They have as well processes which wrap around blood capillaries. These are astrocyte end feet. They keep toxic substances away from the brain.
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What are Oligodendrocytes?
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They form and maintain the myelin sheaths in the CNS.
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What do ependymal cells do?
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They form layers which line internal surfaces of the ventricles of the brain and the central canal of the spinal cord, spaces which are filled with CSF.
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What are microglial cells?
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These function as phagocytes in th CNS, they will phagocytose infecting particles or damaged tissue.
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Can neuroglial cells continue to divide
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Yes. As this occurs throughout adult life, they are able to maintain the integrity of the brain and spinal cord. As a result of this mitotic activity, they can generate tumors. These are gliomas.
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The cerebral cortex of the brain is a layer of grey matter. True/False
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True. These are mostly nerve cell bodies. The outer cortex is only 2-4 mm thick, but contains billions of cell bodies.
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What are the four main lobar area of the brain?
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Frontal
Parietal Temporal Occipital |
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Where is the motor cortex located?
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immediately anterior to the central sulcus is the precentral gyrus which is where the motor cortex is located.
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Where is the sensory cortex/
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Immediately posterior to the central sulcus is the postcentral gyrus which houses the sensory cortex.
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What could be the result if a person damages their frontal lobes?
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That individual could become socially disinhibited, often seriously.
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The parietal lobe contains the sensory cortex. True/False
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True. This is the area of the brain that collects information about what the body has generated in the peripheral sensory receptors and transmitted via sensory neurons.
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Cell bodies are located in the cortex and their connected nerve fibers project down into the white matter of the cerebrum. True/False
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True. In the motor cortex of the precentral gyrus, the cell bodies of the motor cortex generate new nerve impulses which are transmitted via their axons, down through the white matter of the cerebrum, towards the spinal cord.
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In the sensory cortex of the postcentral gyrus, the neuronal cell bodies receive impulses from where?
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They receive impulses which have ascended through the white matter via their dendrites.
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The experience of consciousness is likely a diffuse product of the function of the cerebrum. True/False
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True. This is why we measure Glasgow Coma scales in head injuries. if the cortex is being compressed by rising pressure within the skull, there will be a generalized reduction of cortical function, resulting in a corresponding reduction in the level of consciousness and in the GCS.
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Which structures are contained in the Diencephalon?
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The Thalamus, Hypothalamus and the Epithalamus.
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What is the thalamus responsible for?
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It is responsible for diverse functions, as language, sleep and wakefulness, recent memory and emotion.
It is also a relay center, receiving information from the body via the spinal cord and relaying this on to appropriate areas of the brain. |
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Where do the cranial nerves arise from?
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Cnn 111to X11 arise from the brain stem.
111 and 1V from the midbrain V-V111 from the pons 1X-X11 from nuclei in the medulla oblongata. |
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All cranial nerves are mixed nerves. True/False
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False. Some are motor, some are sensory, and others are mixed.
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Which cranial nerve controls the pupil?
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It is controlled by the thirds cranial nerve which runs under the base of the brain.
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The spinal cord is about how long in the average adult?
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About 45 cm.
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White matter in the spinal cord consists of tracts. True/False
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True. It contains bundles of ascending and descending neurons.
Ascending tracts carry information to the brain. and descending tracts carry information from the brain to the body. |
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Where are motor neuronal cell bodies located in the spinal cord?
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They are located in the ventral horns, and their axons leave in the ventral nerve roots to innervate muscles.
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In the dorsal horns, the grey matter is largely composed of the cell bodies of interneurons(relay neurons. True/False which process signals from the axons of sensory neurons entering via the dorsal nerve root.
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True. They process signals from the axons of sensory neurons entering via the dorsal nerve root.
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The spinal cord has 31 pairs of spinal nerves. True/False
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True.
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Why is a lumbar puncture performed below the third lumbar vertebrae?
|
This is done to prevent accidental damage to the spinal cord.
Below the level of the second vertebral lumbar, large spinal nerves form the lower lumbar sacral and coccyx sections. |
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Are the above mentioned spinal nerves part of the spinal cord?
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No. As the spinal cord has terminated by this level, these large nerves are no longer part of the spinal cord. They are called the "cauda equine or horses tail"
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Are there blood vessels in the subarachnoid space?
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Yes. Numerous blood vessels run in this space. In adults, there is about 150 mls of this fluid surrounding the brain and spinal cord.
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Nerves carrying sympathetic innervation leave the CNS and enter the PNS from which spinal nerves?
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From T1 (thoracici) all the way down to L3 (lumbar), a total of 15 nerves. (Thoracolumbar outflow).
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Nerves carrying parasympathetic innervation leave the CNS and enter the PNS through which cranial nerves/
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111, V11, !X and X. Ps. innervation also leaves via spinal nerves S2-S4 (sacral spinal nerves. (Craniosacral outflow).
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The final synapse between Ps. nerve fibers and the organ or structure innervated uses which neurotransmitter?
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It uses acetylcholine as the chemical transmitter (Cholinergic neurones).
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Do the neurones of the cerebral cortex have the power of mitosis?
|
No. They cannot divide to regenerate damaged nervous tissue.
As cerebral cortical neurones cannot regenerate, this damage can leave a child with cerebral palsy (spasticity) or learning difficulties. |
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When tumors arise in the CNS they are caused by excessive mitosis of the neuroglial cells, not the neurones. True/False
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True. These are the structural and supportive cell types.
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What are the two types of sleep?
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There is rapid eye movement (REM) and Non REM.
NREM is also called slow wave sleep as there is a slowing of the brain waves as detected on an EEG. It may slow down to 1-2 waves per second. The pupils of the eyes constrict. |
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What is REM sleep?
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REM sleep is when dreaming occurs and if a person is woken up they usually remember their dreams.
Pulse, blood pressure and respiratory rates change. |
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After vigourous sleep people tend to have slow wave sleep. True/False
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True.
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All exocrine cells are unicellular. True/False
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False. They may be unicellular, composed of one cell.
Others are multicellular, and these are more complex in structure. |
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|
What type of gland is a goblet cell?
|
It is unicellular. They produce and secrete mucus directly onto the surface of mucus membranes.
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A target cell may have thousands of receptors. True/False
|
True.They may have between two thousand and one -hundred thousand receptors for a particular hormone.
Signal molecules are also called ligands. |
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What is the diameter of the pituitary gland?
|
It is about 1-1.5 cm in diameter.
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Anterior pituitary glandular tissue produces hormones and releases them directly into the blood. True/False
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True.
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What is the posterior lobe of the pituitary gland composed of?
|
Neurological tissue. Hormones produced here are produced in cell bodies located in the hypothalamus.
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What happens with posterior pituitary hormones once they are synthesized?
|
They are packaged into granules which travel down secretory axons before release from the posterior lobe.
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Why is the anterior lobe called the adenohypophysis?
|
It is composed of glandular tissue.
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What are the two hormones secreted by the posterior pituitary gland?
|
Oxytocin and Anti-diuretic hormone (ADH)
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What are two functions of Oxytocin?
|
1. It stimulates the contraction of the uterus.
2. Causes milk release from milk duct contraction. It is used occasionally to induce labor. |
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How does alcohol affect ADH release?
|
It inhibits or discourages the release of ADH.
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Is GHRH a hypothalamic neurohormone?
|
Yes. This stimulates the anterior pituitary cells called somatotrophs to release GH into the blood.
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What is Somatostatin?
|
This is GH- release inhibiting hormone. This inhibits the release of GH.
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What are thyrotrophs?
|
Thyrotrophin releasing hormone (TRH) stimulates the release of TSH which is produced by special cells called thyrotrophs. (anterior pituitary).
CRH----ACTH--- from corticotrophs----cortisol. |
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What is VIP?
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This is hypothalamic vasoactive intestinal peptide. This stimulates the release of prolactin from pituitary cells called lactotrophs or mammotrophs.
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What are the five different types of cells in the anterior pituitary?
|
Somatotrophs
Thyrotrophs Corticotrophs Lactotrophs Gonadotrophs |
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Are hypothalamic neurohormones released into the general circulation like other hormones?
|
No. Once produced in the hypothalamus, they are quickly absorbed by capillaries which drain into portal veins, which then run down the pituitary stalk.
Once these veins reach the anterior pituitary, they divide into capillaries which supply the neurohormones directly to the pituitary cells. |
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Can it be said that neurohormones can be produced in small volumes?
|
Yes. They are not systemically diluted before exerting their effect.
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|
What is the function of FSH in men?
|
It stimulates the production of sperm in the testes, through spermatogenesis.
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What is the function of FSH in women?
|
It stimulates the development of ova each month in the ovaries.
It stimulates the ovaries to release estrogen. |
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What is the functional difference between prolactin and oxytocin?
|
Prolactin stimulates the actual synthesis of milk whereas oxytocin stimulates the ejection of the produced milk from the breasts.
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Does prolactin have a function in men?
|
It does. It can reduce blood levels of testosterone and at high levels may inhibit sperm production.
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|
When are the two periods of growth in a childs development?
|
The first is in the first two years of life with a second spurt at the time of puberty.
Growth stops at about 18-20 years of age, when the growing ends of long bones fuse over in the process of epiphyseal closure. |
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What effect does GH have on bones?
|
It stimulates the proliferation of cartilage cells and osteoblasts in the growth plates. It also stimulates the production of collagen and the mineralization of bone.
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Within the thyroid gland, there are a large number of follicles, which are surrounded by secretory epithelial cells. True/False
|
True. Within these follicles, thyroid hormone is stored in combination with a protein in the form of thyroglobulin.
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When iodine is deficient, how does this structurally affect the thyroid gland.
|
It swells in an attempt to extract more iodine from the blood. This is called a goitre. (Derbyshire neck).
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What are C cells?
|
This is a second form of secretory cell in the thyroid. Sometimes they are called parafollicular cells.
C cells secrete calcitonin. |
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When is calcitonin stimulated/
|
It is stimulated by increased levels of calcium in the blood. It lowers plasma levels of calcium.
More calcium is deposited in the bones. It also increased the excretion of calcium by the kidneys. |
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|
What is the function of parathyroid hormone/
|
This hormone increases plasma calcium levels.
1. It can increase the amount of calcium which is released from stores in the bone. 2.It increases the amount of calcium which is reabsorbed by the nephrons, resulting in less Ca+ being lost in the urine. 3. Acts on the small intestine to augment the amount of calcium which is absorbed from food. |
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Endocrine tissue in the pancreas is located in over a million small pancreatic islets of Langerhan) True/False
|
True. It has both endocrine and exocrine functions.
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What are pancreatic D cells?
|
These cells secrete somatostatin, a product which is the same as the GH release inhibiting hormone produced by the hypothalamus.
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Physiological mechanisms of homeostasis maintain the blood concentration of glucose at around 4.5-7 mmol/L. True/False
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True.
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The core of each islet contains beta cells. True/False
|
True. These are sensitive to increases in blood glucose levels and respond with the secretion of insulin.
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What is contained within the cortex of an islet?
|
It contains alpha cells which are sensitive to falls in blood glucose and respond with the secretion of glucagon.
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What are islet F cells/
|
The cortex of each islet also contains PP (F cells) which produce pancreatic polypeptide and delta cells, and Delta cells which produce somatostatin.
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is there a relationship between Hydrocortisone and inflammation?
|
Yes. It increases the probability of survival by inhibiting the inflammatory process. Inflammation causes pain which may inhibit essential body movement and activity.
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What are two hormones produced by the kidney?
|
Erythropoietin
Calcitriol Renin is also produced by the kidneys and is a part of the renin-angiotensin mechanism. |
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|
What is Calcitriol?
|
This is the active form of vitamin D.
Inactive forms of vitamin D are generated by the skin when exposed to sunlight and absorbed from ingested food. The body is unable to use these forms until they have been activated by the kidneys. |
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|
Is Calcitriol a hormone?
|
Yes. It is produced in the body from a chemical precursor and is transported in the blood to target tissues.
This explains why patients with chronic renal failure lose bone mass, as the vitamin D is essential for normal bone metabolism. |
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|
The secretion of estrogen is mostly stimulated by what substance?
|
It is mostly stimulated by FSH, although leutinizing hormone (LH) may also have a stimulatory effect.
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|
Just before each menstrual cycle begins there is an increase in what substance/
|
In FSH, which stimulates the early ovarian follicle to grow and to start secreting estrogen.
Estrogen is secreted by the developing ovarian follicle during the first 14 days of a menstrual cycle. |
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|
What effect does progesterone have on cervical mucus?
|
It changes the nature of the cervical mucus, but unlike estrogen it makes it more viscous and resistant to the penetration of sperm.
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|
What is chorionic gonadotrophin?
|
If pregnancy occurs the newly developing embryo, (when reaching the blastocyst stage) secretes a hormone called chorionic gonadotrophin (CG).
This has an effect on the CL which is similar to that of LH. The CL will not undergo involution if pregnancy does occur. It will, in fact be maintained for the first three months of the pregnancy by CG. |
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|
Can CG in the blood be measured?
|
Yes. Sensitive tests can measure the presence of CG in the blood about 9 days after fertilization.
The rates of CG secretion rise rapidly and reach a maximum around 10-12 weeks into pregnancy. |
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|
How do contraceptive pills work?
|
They work by artificially increasing blood levels of estrogen and progesterone to inhibit ovulation and prevent conception.
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What substance is basically responsible for girls reaching puberty?
|
Increase in estrogen levels.
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Testosterone is a steroid like hormone synthesized from cholesterol? True/False
|
True. It is produced by the interstitial cells of Leydig, which lay scattered between the sperm producing tubules. Its secretion is stimulated by LH.
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|
List two hormones produced in the thymus.
|
Thymosin and Thymic factor. These hormones stimulate the maturation of T lymphocytes.
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|
Where is the Pineal gland located?
|
It is attached to the roof of the third ventricle in the brain. It weighs about .15 grams.
The pineal gland secretes mealtonin. |
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|
The secretion of melatonin is dependent on what?
|
It is dependent on how much light enters the eye each day. In darker conditions more is secreted.
It plays a role in the circadian rhythm. |
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|
What are the four basic layers of the GI tract?
|
From the inside, the mucosa, submucosa, a muscular layer and the outer serosa (adventitia).
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|
What type of cells are found in the mucosa?
|
It is composed of a simple columnar epithelium.
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|
Describe the smooth muscle in the GItract.
|
There are 2 layers of smooth involuntary muscle.
The outer layer is composed of longitudinal muscle fibers and the inner layer of circular muscles. The stomach has another layer of muscle that runs in an oblique direction. |
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|
How is the activity of the muscular layer neurologically coordinated?
|
It is coordinated by a network of intrinsic, autonomic nerve fibers called the myenteric plexus.
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|
What is the mesentery tissue?
|
This is a double layer of peritoneum which connects the jejunum and ileum to the posterior abdominal wall. Blood vessels which supply the small intestine run between the layers of the mesentery.
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|
By the time the same double sheet of mesentery reaches the small intestine, it is about 6 meters long. True/False
|
True.
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|
What is the Omentum?
|
The greater omentum is a large apron like peritoneal fold of tissue which lies in front of the organs of the GI tract.
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|
Why is the Omentum sometimes called the policeman of the abdomen?
|
It is able to seal off and consolidate areas of infection. This prevents spread throughout the peritoneal cavity.
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|
What is the function of Trypsin?
|
This is an enzyme which will digest proteins. This is formed as trysinogen in the pancreas. Trypsinogen is inactive. When exported from the pancreas into the lumen of the small intestine, it will then be converted into the active form.
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|
How many deciduous teeth do children have?
|
They have 20 decidual teeth.
Adults should have 32 permanent teeth. |
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|
What are the three pairs of salivary glands?
|
The parotid,
Submandibular Sublingual. These all secrete saliva. |
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|
What mechanism stimulates the secretion of saliva?
|
It is a parasympathetic stimulation (Vagus). Two salivary nuclei are located in the brain stem.
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|
What is salivary amylase?
|
It is the digestive enzyme that starts the digestion of CHO by cleaving starch molecules into maltose.
A single unit of a polysaccharide is called a monosaccharide. |
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|
The esophageal lumen is lined with what type of tissue?
|
It is lined with stratified squamous epithelium. Mucus is secreted from this lining to lubricate the passage of food.
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|
What is the esophageal sphincter?
|
The esophageal sphincter (cardiac sphincter) regulates the passage of food into the stomach.It is located in the terminal 4 cm of the esophagus and it is normally closed.
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|
The Gastric glands are lined with what type of cells?
|
They are lined with several types of specialized exocrine cells which secrete the various gastric juices.
Cells around the neck of the pits are mucus cells which secrete mucus. |
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|
In the proximal area of the stomach there are about 100 gastric pits per cubic mm of gastric mucosa. True/False
|
True.
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|
What is the most common type of cell in the gastric pits?
|
These are the chief cells (zymogenic cells). These produce pepsinogen, which exits the pit into the lumen of the stomach. It requires contact with HCl o convert it to pepsin.
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|
What are Oxyntic cells?
|
These are Parietal cells. They secrete HCl acid and Intrinsic factor.
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|
What is intrinsic factor?
|
It is a glycoprotein which binds with vitamin B12 to allow this nutrient to be later absorbed in the intestine.
Pernicious anemia results from lack of Intrinsic factor. |
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|
What are G cells?
|
In addition to neuronal control, the presence of proteins in the stomach initiates secretion of Gastrin from specialized mucosal G cells.
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|
What is Gastrin?
|
It is an endocrine hormone which circulates in the blood, and stimulates the Chief cells to secrete more pepsinogen and the Parietal cells to produce more HCl.
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|
What is gastric Histamine?
|
Histamine is also produced by the gastric mucosa. Parietal cells are able to detect this chemical via histamine type H2 receptors. Histamine stimulates the parietal cells to secrete more HCl acid.
Drugs such as Ranitidine and Cimetidine reduce gastric acid by blocking the H2 receptor sites on the parietal cells. |
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|
What is the function of Rennin in the stomach of young children?
|
In young children the stomach secretes rennin. This enzyme coagulates milk into a curd to prevent it from running through the stomach before it can be acted on by pepsin.
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|
The common bile duct joins with the pancreatic duct forming a common duct called the ampulla of the bile duct. True/False
|
True. This structure then communicates with the lumen of the duodenum.
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|
How is reflux from the duodenum into the ampulla avoided?
|
It is prevented by the sphincter of Oddi.
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|
What are some substances found in Pancreatic juice?
|
It contains pancreatic amaylase, pancreatic lipase, chymotrypsinogen, trypsinogen. Sodium bicarbonate is also produced which gives pancreatic juice an alkaline pH.
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|
What is necessary to stimulate the release of CCK? (Cholecystokinin)
|
The arrival of chime from the stomach into the duodenum and upper parts of the jujunum stimulates the release of an endocrine hormone called CCK.
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|
What is the function of CCK?
|
It is produced by specialized I cells in the duodenal mucosa. as an endocrine hormone CCK circulates in the bloodand stimulates the secretion of pancreatic digestive enzymes.
It also causes contraction of the gallbladder. |
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|
The duodenum is the most common site for peptic ulcers. True/False
|
True.
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|
List some enzymes situated in enterocytes.
|
Maltase, sucrase, lactase and peptidases.
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|
Where is trypsinogen converted into trypsin?
|
This occurs in the lumen of the bowel. This is achieved by the action of enterokinase, an enzyme secreted by the mucosa of the small intestine.
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|
Once trypsin is activated, what will it itself activate?
|
Once activated, trypsin in turn activates chymotrypsinogen which becomes chymotrypsin.
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|
Both Trypsin and Chymotrypsin will continue to have what effect once formed?
|
They both act to break down lengths of proteins and peptides into smaller peptide units.
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|
Regarding the digestion of CHO, what effect does HCl have on saliovary amylase?
|
The action of salivary amylase is blocked by the acidic environment of the stomach.
Pancreatic amylase continues to break down starch, which is a polysaccharide, into disaccharide sugars. |
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|
What is the function of Lactase?
|
Lactase breaks down milk sugar lactose into one molecule of glucose and one of galctose.
Sucrase breaks down sucose into glucose and fructose. |
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|
Around 90% of absorption takes place in the small intestine. True/False
|
True. This occurs especially in the Jejunum and Ileum.
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|
|
Where are the villi of the small intestine found?
|
The circular folds of the small intestine have a highly infolded surface that are covered with villi.
The function of these small projections, 0.5-1 mm high, further increase the surface area. The villi are lined with enterocytes, the surfaces of which are also highly infolded. Small projections of microvilli project from the surface of the enterocytes. Each individual cell has about 3,000 microvilli. |
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|
What do villi contain?
|
They contain a central lymphatic vessel called a lacteal.
Fatty acids are able to absorb readily into the enterocytes as they are lipid soluble. Being lipid soluble, they cannot be transported in the water based blood or lymphatic fluid without modification. |
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|
What happens as fatty acids and glycerol pass through the enterocyte?
|
They are recombined to form tryglycerides. These aggregate into globules and the enterocyte then coats them in water soluble protein so they may be transported in water. This total structure is called a chylomicron.
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|
Veins draining the intestine combine to form the hepatic portal vein which carries blood directly to the liver. True/False
|
True.
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|
|
Everyday an individual swallows about how much saliva?
|
About 1.5 litres of saliva.
Gastric secretions add 3 litres of fluid Bile- another 0.5 litre Pancreas secretes about 1.5 litres of pancreatic juice Total intestinal juice is about 2 litres a day. |
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|
The colon secretes about 200 mls of fluid over 24 hours. True/False
|
True.
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|
|
Bacteria in the colon produce what type of waste gases?
|
Methane
Hydrogen Hydrogen sulfide These give rise to flatulence. Between 0.5-2 litres of gases are expelled each day. |
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|
Mass movements in the colon involve active muscular contractions and may generate pressures within the colon as high as 100mm/Hg. True/False
|
True. Once fecal material has entered the rectum, the stretching effect on rectal walls will initiate the desire to defecate.
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|
App. how much bile does the liver produce each day?
|
It produces about 500 ml of bile each day.
The bile is secreted from the liver via the right and left hepatic ducts which merge to form the common hepatic duct. |
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|
What is the function of the cystic duct?
|
It transports bile from the common hepatic duct into the gall bladder where it is stored and concentrated.
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|
The liver receives about how much blood from the hepatic portal vein?
|
It receives about 70% of its blood from this vein.
On average, over a litre a minute passes into the liver from the portal vein. |
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|
What is the difference between the HPV and the hepatic veins?
|
The HPV carries blood to the liver from the gut whereas the hepatic veins drain blood from the liver, back into the systemic venous return of the inferior vena cava.
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In young children, the relatively large size of the liver explains why their upper abdomen protrudes. True/False
|
True.
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|
What is an hepatic lobule?
|
The liver has thousands of these. They are situated within the lobes and separated by connective tissue.
They are round to hexagonal in shape. At the corners of the lobules are branches of the HPV, hepatic artery and bile ducts. These three vessels are called a triad. |
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|
A normal liver contains about how many lobule units?
|
About 50-100,000 lobule units which vary in diameter from 0.8 to 2 mm. They are the functional units of the liver.
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|
What is an heaptic cellular plate?
|
Typically the hepatocytes are arranged in a row, two cell sthick. These two rows of cells are an hepatic plate.
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|
What are hepatic sinusoids?
|
Sinusoids are the hepatic capillaries. In between two hepatic cellular plates are the blood sinusoids. It is essentially a type of blood capillary with very porous walls, allowing more contact than usual between the blood and tissue cells.
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|
How are hepatocytes supplied?
|
They are supplied with nutrient rich blood from the hepatic portal vein and oxygenated blood from the hepatic artery.
Hepatocytes lining the sinusoids are able to selectively absorb substances from the blood, carry out chemical processes, and then secrete these products back into the blood of the same sinusoid. |
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|
What are Kupffer cells?
|
Liver sinusoids have macrophages caslled Kuppfer cells (reticuloendothelial cells) in their walls. They break down old RBCs, recycling the amino acids and excreting the bilirubin. They phagocytize bacteria as well.
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|
What is a biliary canaliculus?
|
two hapatocytes touching each other, (heaptic cellular plate). the canaliculus is formed between the two rows of cells. Bile produced in these cells is only excreted into the canaliculi. Bile is only excreted from one side off the hepatocyte as the other side is in contact with the blood.
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In the liver there is a largger space between the walls of the sinusoids and the tissue cells than is normal in most other tissues. What is this space called?
|
This space between the capillary wall and the hepatocytes is called the perisinusoidal space or the space of Disse.Once formed from the plasma tissue fluid circulates through the perisinusoidal space bathing the individual hepatocytes.
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|
About haslf of the total volume of lymphatic fluid formed in the body is derived from the liver. True/False
|
True.
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|
What is Bile?
|
It is an alkaline fluid with a pH of about 8. It is mostly water, but also contains bile salts and bile pigments. these salts are important for the emulsification of fats. they are produced from cholesterol in individual hepatocytes.
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|
Are there any other substances incorporated into bile?
|
Yes. Sodium chloride and bicarbonate. Bilirubin is the primary bile pigment.
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|
When Hb molecules are broken down what yellow pigment is formed?
|
Bilirubin is formed. It is extracted from the blood by liver cells. In the liver cells, bilirubin is joined onto another molecule called glucoronic acid. This is clled conjugation.
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|
What is the purpose of conjugation?
|
It increases the solubility of bilirubin so it may be carried in solution in bile.
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|
The liver converts galactose and fructose into glucose. True/false
|
True. Galactose and fructose may arrive from the gut via the hepatic poratl vein and always converted into glucose.
The liver cells can also convert amino acids into glucose. |
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|
The process of converting one amino acid into another is called___________________________.
|
Transamination.
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|
What occurs if more protein are consumed than are required?
|
The excess amino acids are utilized for their energy yielding content.
Amino acids must first be broken down before they can produce carbohydrates or fats. This is called deamination. |
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|
What are the essential amino acids?
|
Essential
Histidine* Isoleucine Leucine Lysine→ Methionine Phenylalanine Threonine Tryptophan Proline* Valine |
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|
What is the most abundant plasma protein?
|
Albumin. It is produced by hepatocytes. It is essential for blood osmolarity.
It also acts as a carrier molecule. Some drugs are carried by albumin. |
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|
Where is angiotensinogen produced?
|
It is produced in the liver. It is an essential part of the RAAS system.
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|
Specifically, when proteins are broken down, what is left over?
|
Nitrogen. It is a waste product.
N2 in solution forms toxic ammonia (NH3) which must be rapidly removed from the blood. |
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|
Is ammonia produced anywhere else?
|
Additional ammonia, produced by bacteria is absorbed from the gut.
Hepatocytes take up ammonia and chemically convert it into a much less toxic, highly soluble substance called urea. |
|
|
Does the liver store vitamins?
|
Yes. It stores the fat soluble vitamins A, D, E and K, and can hold rserves for vitamin B12.
Enough Vit. A is stored for 10 months. |
|
|
Iron is stored in the liver as what specific substance?
|
Ferritin.
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|
Why are many drugs oxidized in liver cells?
|
They are oxidized or conjugated to increase their solubility in water.. These processes are facilitated by enzymes, the best known group is Cytochrome P450.
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|
Why is the right kidney a little lower than the left?
|
This is due to the presence of the liver above.
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|
What type of tissue surrounds ther outer surface of each kidney?
|
There is a layer of collagen rich fibrous tissue which comprises the renal capsule.
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|
The renal medulla is comrised of structures called the......
|
renal pyramids. There are usually 5-11 per kidney. Between the pyramids are structures called the renal columns.
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|
The kidneys comprise app. 0.5% of body mass. True/False
|
True. In an average 70kg adult, the kidneys receive about 1200 mls of blood per minute. This is about 20% of total cardiac output.
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|
|
App. how many nephrons are in each kidney?
|
About 1 million.
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|
What type of cells are found in the outer or parietal layer of Bowman's capsule?
|
Squamous cells.
The inner layer is made up of cells called podocytes. Between these two layers is a capsular space. |
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|
In the proximal convoluted tubule, why is this structure "convoluted"?
|
Convoluted means coiled. There is a greater length of tubule that is contained in a smaller area.
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|
Where are pedicels found?
|
Podocytes form the inner layer of the capsule. These cells have fine extensions called pedicels which wrap around the glomerular capillary and form a physical sieve. Between the pedicels and podocytes is a thin membrane called the slit membrane.
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|
What is the endothelial capsular membrane?
|
The endothelial cells of the capillaries, basement membrane and podocytes from the endothelial -capsular membrane.
This is a dialyzing membrane. |
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|
What exactly is dialysis?
|
It is a physical process involving the separation of small molecules in solution from larger ones through a dialyzing membrane.
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|
What does GFR refer to?
|
This is Glomerular filtration rate. This refers to the volumes of glomerular filtrate formed over a period of time. This is about 125 ml a minute which adds up to about 180litres per day.
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|
Where are Mesangial cells found?
|
They are located between the glomerular capillaries.
Under the glomerular endothelial cells is the glomerular basement membrane, (GBM). This forms a structural base for the glomerular capillary endothelial cells and also acts as a dialyzing membrane. |
|
|
What are the normal plasma concentrations of sodium?
|
About 135-146mmol/L.
Potassium- 3.5-5 mmol?l Chloride- 98-106mmol/L Magnesium- 0.7-1.1mmol/L Phosphate- 0.8-1.5 |
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|
In health, should the urine contain amino acids or glucose?
|
No. Other substances may not be fully reabsorbed.
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|
App. 50% of urea is absorbed into the blood. true/False
|
True. The other 50% remains in the filtrate to enter the urine.
Creatinine is similar in its absorption protocol, though its measurements are different. |
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|
An alkaline solution can absorb hydrogen ions. True/False
|
True. The hydroxyl ion (OH) can absorb an H+ to form water.
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|
Normally,urine is about 95% water and 5% dissolved substances or solutes. True/False
|
True. The normal specific gravity of urine is about 1.010-1.035.
|
|
|
What is specific gravity?
|
It describes the mass of a substance as a ratio to the mass of pure water.
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|
The metabolism of amino acids by body clls results in the formation of what?
|
Waste nitrogen.
This combines with water to form ammonia, which is toxic. The liver facilitates a chemical reaction which combines ammonia with CO2 to form urea, which is much less toxic. Creatinine and uric acid are other nitrogen containing wastes. |
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|
Normal urine may occasionally contain some ketones. true/False
|
True. This is true, especially if the person is consuming very little food.
Ketones are products of fat metabolism. |
|
|
What can cloudy urine indicate sometimes/
|
It may indicate the presence of WBCs due to some infection.
|
|
|
Where does the color of urine come from?
|
It comes from a breakdown product of bile called urochrome. Urine is slightly acidic.
High protein diets tend to increase acidity, and vegetarian diets cause alkaline changes. |
|
|
what is the significance of nitrite in the urine?
|
This may be the result of bacterial activity and leukocyte eserase from WBCs.
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|
|
What are the two principle cells found in the Juxtaglomerulary apparatus?
|
Granular cells are immediately close to the afferent arterioles.
Secondly, the macula densa cells comprise part of the wall of the ascending loop of Henle containing the macula densa cells. |
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|
What happens if the blood pressure in the afferent arteriole is reduced?The
|
JGA cells respond by secreting the enzyme renin into the blood.
Angiotensinogen is present in the blood. It is produced by the liver and is inactive. when renin acts on angiotensinogen it converts it into another shorter protein called angiotensin 1. |
|
|
What proceeds once angiotensin 1 is formed?
|
As angiotensin 1 passes through the lungs it is converted into angiotensin 2 by an enzyme called angiotensin converting enzyme. A2 is a powerful vasoconstrictor. Blood pressure will increase.
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|
|
Where is vitamin D3 found?
|
Vitamin D eaten or generated by the skin when exposed to sunlight, is in the form of vitamin D3, which is cholecalciferol.
This form is inactive. However, in the kidneys it is converted into calcitriol, which is an active form. |
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|
Calcitriol is much more active than vitamin D3. True/false
|
True. The conversion is facilitated by an enzyme produced in the proximal tubules.
This will increase calcium absorption. It will also increase bone deposition of calcium. This is why patients in renal failure often lose bone mass. |
|
|
Where is EPO produced?
|
It is produced by fibroblast type cells in the interstitium of the renal cortex and outer medulla.
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|
|
What is the name of the smooth muscle found in the bladder?
|
This is the detrusor muscle.
|
|
|
How long is the urethra in men?
|
About 18-20 cm.
The first 3-4 cm of the male urethra pass through the tissue of the prostate. This lumen is compressed when the prostate enlarges. |
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|
Urine is commonly passed when about 250-280 ml of urine has accumulated in the bladder. True/False
|
True. The bladder can fill to 500ml if necessary, but this will cause a strong urge to urinate.
|
|
|
What is the average skin surface area of an adult?
|
It is about 1.5 to 2m squared.
It is arranged in two layers. The epidermis and the dermis. |
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|
What are dermal; papillae?
|
Components of the dermis which rise into the area of the epidermis are the dermal papillae. This provides a great deal of resistance to shearing forces, preventing the epidermis from being rubbed away.
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|
|
What is a blister?
|
A blister is a collection of fluid between the dermis and the epidermis or even between the layers of the epidermis.
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|
The epidermal-dermal junction is marked by a basement membrane. True/false
|
True. But it is actually incomplete. This area is called the basement membrane zone.
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|
Living epidermal cells are positioned on the basement membrane zone. True/False
|
true. This area is called the germinative layer because there an ongoing mitosis in epidermal cells generating new tissue.
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|
|
What are Keratinocytes?
|
Epidermal cells are referred to as keratinocytes and about 10% of these are epidermal stem cells.
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|
|
What does a keratinocyte stem cell do?
|
It divides to produce a new stem cell and another keratinocyte. The stem cell remains in the epidermis where it can divide in the future.
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|
|
About how long is complete turnover time for the epidermis?
|
It is about 2 months.
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|
|
One of the lipid based molecules found in the epidermis is called dehydrocholesterol. True/False
|
True. When this substance is exposed to sunlight it is converted into a form of vitamin D. This form will be converted into a much more active form in the kidneys.
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|
|
In childre, a lack of vitamin D can result in rickets. true/false
|
True.
|
|
|
What are melanocytes?
|
They are a specialized form of cell found in the epidermis which synthesize and secrete melanin.
In order to aid its distribution, melanocytes have projections called dendrites. |
|
|
Do albinos produce melanin?
|
No. They have no melanin to give color to their skin, hair or eyes.
|
|
|
Where are Fibroblasts found?
|
Fibroblasts are found throughout the dermis and are the cells which produce the collagen and elastic fibers.
In fact, the dermis has a protein called proteoglycan which is also mostly derived from fibroblasts. |
|
|
What is an alternative term for ground substance?
|
Intercellular matrix.
|
|
|
Which two substances mostly attract water into the dermis?
|
Collagen and matrix.
|
|
|
The common form of sweat glands are also eccrine glands. True/false
|
True.
|
|
|
What are Apocrine glands?
|
These are found mostly in the axilla, groin and around the genitalia.
Apocrine ducts open into hair follicles. They begin functioning at puberty in males and females, under hormonal influences. |
|
|
What are Meissner receptors?
|
These are specialized structural receptors located just under the epidermis, and are sensitive to touch. They generate sensory nerve impulses.
|
|
|
Where are Merkel cell receptors located?
|
These are also touch receptors located just above the basement membrane in the lower area of the epidermis.
They innervate hair follicles so one can sense touch from hair. |
|
|
Why do older individuals have more sensitivity to sunlight?
|
Melanocyte populations are reduced by 10-20% in older people.
|
|
|
When does clinical cyanosis become most apparant?
|
It becomes most apparant when the O2 saturation drops below 86%.
|
|
|
What is central cyanosis?
|
This may be observed in the chest, neck, lips or tongue. There is a reduction in the levels of o2 in the systemic arterial blood as might be caused by suffocation, lung or heart disease.
|
|
|
What is peripheral cyanosis?
|
This is seen more in the extremities, such as in the fingers, toes, and tips of the nose or ears. This is the result of a slowing of blood flow through a peripheral area.
|
|
|
Do contracting muscles produce a lot of heat?
|
They produce much heat when contracting. However, when they are contracting, only about 20% of the energy they use is converted into movement, the remainder is converted into heat.
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|
|
In heat loss, what is meant by the surface area to volume ratio coefficient?
|
Larger bodies lose heat more slowly.They will have a lower surface area to volume ratio, which when compared to their mass they have a rather small surface area through which to lose heat.
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|
|
Smaller bodies have a greater surface area compared to their volume. True/False
|
True. More heat will be lost through this relatively large surface area.
|
|
|
What is heat conduction?
|
In conduction, heat passes from warm objects to cooler ones via direct contact.
This is best exemplified with water. It is a good conductor of heat with a thermal conductivity 25 times greater than dry air. |
|
|
What is latent heat of vaporization?
|
When water changes from a liquid into a vapor it requires a large amount of energy.
|
|
|
When does Convection occur?
|
Natural convection occurs when air near the surface of the body is warmed. Molecules vibrate more vigorously
the density of warm air is less than that of cold.. |
|
|
What is radiation?
|
All hot objects radiate heat in the form of infrared radiation. heat is transferred away from the body in the form of radiation.
|
|
|
When is hypothermia said to have occurred/
|
When the body's core temperature drops below 35 C.
|
|
|
Is there a temperature change in ovulating women?
|
Yes. The temperature may drop slightly for about 24 hours after ovulation. Temperatures are about 0.5C higher during the second half of the menstrual cycle.
|
|
|
Core temperature is detected how in the body?
|
It is detected by deep body sensors, located in the vena cava, esophagus and stomach.
|
|
|
Can pyrexia be a result of tissue damage?
|
Yes. This may be explained by damaged body cell membranes releasing fatty based molecules which are converted into prostaglandins which function as pyrogens.
|
|
|
What happens when a body tissue freezes?
|
Ice crystals form in the cytosol of the cells. The expansion of these crystals results in rupture of cell membranes disrupting tissue integrity.
|
|
|
Why is brown fat brown?
|
The brown color is the result of large numbers of mitochondria the fat cells contain.
|
|
|
Can the metabolic rate of the body change with changes in temperature?
|
Yes. At a temperature of 27C, the metabolic rate is 2.5 times lower than at 37C.
|
|
|
Is there a relationship between hypothermia and sleep?
|
Yes. It is important to avoid sleeping during episodes of hypothermia. Being awake will continue to generate heat by voluntary muscular activity and so maintain metabolic rate and core temperature.
|
|
|
Why can core temperature drop in surgical patients?
|
General anesthesia may reduce vasoconstricting tone, allowing warm blood to perfuse the subcutaneous tissues. Heat will be lost from the body.
|
|
|
Platelets are formed from a type of WBC. True/False
|
True. This occurs in red marrow.
|
|
|
Red marrow is found in the ends of long bones of the arms and legs. true/False
|
True. It can also be found in the sternum, ribs, pelvis, skull and vertebra.
Yellow marrow is generally found in the shafts of long bones. |
|
|
What is a metaphysis?
|
Between the epiphysis and the diaphysis is the metaphysis.
The metaphyses have the growth plates which consist of cartilage. |
|
|
What is the epiphyseal line?
|
In adult bones all of the cartilage in the growth plates has been replaced by bone leaving an epiphyseal line.
|
|
|
When the end of one epiphysis articulates with another epiphysis, what type of tissue exists between them?
|
The ends of the bone surface are covered with articular cartilage. It is a smooth layer of hyaline cartilage, which is intended to reduce the friction between the two ends.
|
|
|
If a bone is fractured, how do the osteogenic stem cells react?
|
The stem cells from the periosteum divide and differentiate into osteoblasts which secrete collagen to provide the structural framework fro the regenerating bone.
|
|
|
Where is the medullary cavity found?
|
Within the diaphysis(shaft) is a cylindrical space. This is the medullary cavity.
|
|
|
Basically, what does bone tissue consist of?
|
It consists of about 25% collagen fibers, and 50% crystallized mineral salts, with the remaining 25% being water.
|
|
|
What does the collagen provide?
|
It provides structure, flexibility, and high tensile strength.
Mineral salts are deposited onto this collagen matrix where they crystallize causing the tissue to harden. This is calcification. |
|
|
What are the two forms of bone tissue?
|
Compact and Cancellous bone(spongy bone)
|
|
|
What are Volkmann's canals/
|
These are perforating canals that carry blood vessels into deeper central Haversian canals.
|
|
|
What are bone lamellae/
|
Surrounding the central canals are rings of calcified collagen fibers which form the bulk of the compact bone tissue. These rings of extracellular calcified tissue from thin plates of bone called lamellae.
|
|
|
Where do osteocytes reside?
|
They reside in small spaces called lacunae situated between the lamellae.
|
|
|
What are osteocytic canaliculi?
|
Osteocytes have thin projections which lie in microscopic spaces called canaliculi.
The canaliculi connect with the central canals. |
|
|
O2 diffuses down a diffusion gradient from the central canal out to the osteocytes. True/False
|
True. This is done basically in the same way CO2 diffuses down a diffusion gradient from the osteocytes to the central canal.
|
|
|
Canaliculi connect the central canal with the osteocytes located in the lacunae. True/False
|
True. Canaliculi provide the avenue of communication between osteocytes and the blood supply of the central Haversian canals.
|
|
|
What are Osteons?
|
The combination of a central canla, the vessels it contains, the surrounding lamellae, osteocytes, lacunae, canaliculi and tissue fluids from units called Osteons. These are also referred to as Haversian systems.
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|
|
Describe spongy bone.
|
Spongy bone is made up of an irregular three dimensional lattice of thin columns of bone called trabeculae.
They are similar to compact bone but, there are no osteon systems. |
|
|
Where are osteogenic cells found?
|
They are found in the lower part of the periosteum, endosteum and lining the central canals within bone which carry blood vessels.
They divide to produce osteoblasts. |
|
|
In connective tissues a blast cell is one which secretes what?
|
Extracellular matrix.
|
|
|
How are osteoblasts similar to fibroblasts?
|
They secrete collagen and an associated amorphous matrix ground substance.
Amrphous means that it has no fixed structure. |
|
|
When do osteoblast officially become osteocytes?
|
As osteoblasts secrete collagen they eventually become surrounded and encased by their own product secretion. They are now osteocytes.
|
|
|
What are osteoclasts?
|
These are large cells which form when several monocytes merge together.
They secrete enzymes capable of digesting the protein which forms collagen. They also secrete acids which dissolve calcium salts. |
|
|
Give some examples of irregular bones.
|
The vertwebrae, calcaneous, some facial bones and the pelvic bones.
sesamoid bones are found within tendons. The patellae are examples. |
|
|
The axial skelton consists of 80 bones. True/False
|
True. There are 8 cranial bones, with 14 facial bones.
|
|
|
The vertebral column has 26 separate bones, and there is one sternum with 12 pairs of ribs. True/False
|
True. There are 6 auditory ossicles.
|
|
|
What is the anatomical name for C1?
|
It is the Atlas.
C2 is the Axis. There are 12 thoracic vertebrae. |
|
|
How many total bones are there in the appendicular skeleton/
|
There are 126.
|
|
|
In a fibrous joint how are two bones held together?
|
By collagen rich fibrous connective tissue.
|
|
|
What are sutures?
|
Fibrous tissues hold the various bones of the skull together across narrow joints called sutures.
|
|
|
What are fontanels?
|
At birth there are two areas of the cranial cavity covered by tough membranes as opposed to bones. These gaps between the skull bones are the anterior and posterior fontanel.
|
|
|
Bone growth covers the small posterior fontanel by about 2 months of age. True/False
|
True. The larger anterior fontanel remains palpable until 18-24 months.
|
|
|
The first ten ribs attach to the sternum via cartilage. true/false
|
True.
|
|
|
Describe the intervertebral discs.
|
These discs have an outer ring of fibrocartilage called the annulus fibrosus. The center is the nucleus pulposus. It is filled with a gelatinous substance which permits movement between two vertebrae.
|
|
|
What is the name of the inner layer of thwe joint capsule?
|
It is the synovial membrane.
It is vascular and produces synovial fluid from components in the plasma. It fills the articular cavity. The fluid is at a slight negative pressure which improves joint movement and stability. |
|
|
Describe the texture of synovial fluid.
|
In appearance it is similar to the white (albumin) of an uncooked egg. It allows a high degree of lubrication.
It also transports O2 and nutrients to the articular cartilage. Macrophages exist within this substance. |
|
|
On radiographs of joints, a wide gap appears to separate the adjacent bones. Why is this?
|
This is due to cartilage covering the articulating surfaces, which is more transparant to X rays than bone.
|
|
|
List three hinge joints.
|
The elbow, the knee and the interphalangeal joints.
|
|
|
What is the odontoid process?
|
The odontoid also called the dens process of the 2nd cervical vertebra (of the axis) projects through a hole (vertebral foramen) in the first cervical vertebra (the atlas). The head moves from side to side as the atlas rotates over the odontoid process. This is the atlanto-axial joint.
|
|
|
Give another example of a pivot joint.
|
Between the radius and the ulna, in order to permit roatation of the hands, turning the palms up or down (pronation and supination)
|
|
|
Which structures form the Temperomandibular joint?
|
There is a condylar process on the upper part of the mandible which fits into the mandibular fossa. This is actually an elliptical depression in the temporal bone of the skull.
|
|
|
Give another example of a condyloid joint.
|
These would include the wrist, knuckles and between the occipital and the atlas.
|
|
|
What is a saddle joint?
|
In a saddle joint, the two bone ends resemble reciprocally shaped saddles .
These joints allow a greater freedom of movement than condyloid joints. These joints are found between the metacarpal bones of the thumb and the trapezium, and in the sternoclavicular joint. This joint permits the thumb to touch all of the other finger tips in the movement of opposition. |
|
|
What are gliding joints?
|
These are also called planer joints. They have flat or slightly curved articulating surfaces. These are found between the carpal bones and the tarsal bones.
|
|
|
What is a subluxation of a joint?
|
This is a partial dislocation of a joint where there is a separation of the articulating surfaces, but the bone ends remain connected.
|
|
|
A muscle is enclosed within a sheath of tough fibrous tissue caslled the............
|
The muscle fascia.
at the ends of the muscle the fascia is continuous with the muscle tendon, which connects to the periosteum. |
|
|
Differentiate between lever and fulcrum.
|
during movement bones function as levers and the joints as fulcrums, a fulcrum being a fixed point around which a lever acts.
|
|
|
When a muscle is not contracting, is it fully relaxed?
|
No. A few fibers will be contracting giving rise to muscle tone.
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|
|
Is glycogen stored in muscle?
|
yes. In times of starvation, muscles will release amino acids to supply essential physiological needs.
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Are ligaments ever found within a joint capsule?
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Yes. The ligament of the head of the femur connecting to the acetabulum.
Within the knee joint capsule are the two cruciate ligaments. |
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Where are bursae found?
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They are little bags of fluid. They are found around bony prominences such as the knees, elbows and shoulders.
The connective tissue inside is lined with synovial membrane which secretes synovial fluid. |
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What causes the body to become stiff and rigid after death?
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This muscle contraction occurs as ATP is no longer synthesized in the dead muscle.
in normal physiology some ATP is required to facilitate normal muscle relaxation. |
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What is the scrotal septum composed of?
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It is composed of connective tissue and contains as well, some smooth muscle fibers.
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Good sperm production requires what temperature/
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It requires a temperature of 3 C below the normal body core temperature..
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What isd the tunica albuguginea?
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each tesatis contains a surrounding capsule of white dense fibrous tissue. this is the tunica albuginea.
This fibrous structure folds inwards to form numerous septa which divide each testis into 2-300 lobules. |
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What are the Seminiferous tubules?
|
Within each lobule there are 1-3 tightly coiled tubules foming closed loops which open at the top to allow sperm to exit. These are the seminiferous tubules. there are about 400-600 per testis.
if straightened out, each seminiferous tubule would be about 70-80cm. |
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Differentiate between sperm and spermatozoa.
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They are the same. sperm cells are produced from a population of stem cells called spermatogonia.
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Where are spermatogonia found?
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They are found on the basement membrane of the seminiferous tubules and have been present in the testis since the individual was an embryo. these are the germ cells. They pass on the genetic information.
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All sperm and ova (gametes) must have 23 chromosomes. true/False
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True. when fertilization occurs the newly formed zygote has 46 chromosomes.
Meiosis ensures that half of the formed sperm contain an X chromosome, and half a Y chromosome. This biologically ensures the same number of boys as girls. |
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About hoe many sperm are produced?
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About 300 million are produced each day.
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How is sperm locomotion enabled?
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By contractile bundles of microscopic filaments running from the neck through the tail.
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Where do sperm mature?
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Sperm mature within the tubules of the epididymis over a period of about 2 weeks. if not released, they be stored up to 2 months.
they are propelled by the ductus epididymis smooth muscle. |
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What is the aversage length of the urethra in men?
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It is about 20cm long.
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Fluid from the seminal vesicles contains the monosaccharides sugar fructose. true/false
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True. This is employed by trhe mitochondria in the sperm to produce the energy required for sperm motility.
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Do Prostaglandins have a function in the sperm fluid?
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Yes. They stimulate sperm motility and may stimulate muscular contraction in the female reproductive tract.
Seminal vesicle fluid also contains clotting factor proteins. True/False |
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Seminal vesicle fluid also contains clotting factor proteins. True/False
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True. these clotting proteins help semen to coagulate in the vagina after ejaculation. Once coagulated, it is less likely to run out of the vagina.
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About how many sperm are there in an average ejaculate sample?
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there will be 2.5-5 mls of semen, containing about 100 million sperm per ml.
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What is a vasectomy?
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It is employed as an effective means of male sterilization. a small section of the ductus deferens is removed from the spermatic cord, before entering the pelvic cavity. the ends are then closed.
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On either side of the penis, the cylindrical masses of tissue are called the..........
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corpora cavernosa.
Between thesae 2 structures is a third smaller cylinder of tissue called the corpus spongiosum. The urethra runs through the spongiosum. These 2 structures comprise the erectile tissue of the penis. |
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The interstitial cells of Leydig secrete........
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testosterone.
At puberty testosterone and sperm production are stimulated under the influence of anterior pituitary gonadotropin hormones, LH and FSH. |
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In men, FSH with testosterone stimulates spermatogenesis. True/False
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True. LH stimulates testosterone secretion.
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In fetal life the Y chromosome causes the early genital tissues to produce testosterone. True/False
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True. If the stimulation from the Y chromosome does not occur, a female will develop.
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Do men have estrogen in their blood?
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yes.Most of it is formed by converting testosterone into estrogen in the liver.
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From puberty to menopause, the vagina is heavily colonized with bacteria. what is a major function of this bacteria?
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The bacteria ferment glycogen to form lactic acid.
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What are the two primary functions of the ovaries?
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They produce the female sex hormones estrogen and progesterone, and they produce and release the ova.
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When a female is born, her ovaries already have all of the immature potential ova she will ever produce. true/false
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True.
These ova are surrounded by a single layer of follicular cells and together they form a primordial follicle. |
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How long is an average ovarian cycle?
|
it is about 28 days. day 1 is considered the first day of menstruation because it is obvious when this occurs. The first half is the follicular phase.
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When does the follicular phase end?
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It ends with ovulation, which usually occurs on day 14.
The second half is called the luteal phase and continues from ovulation to the onset of the next menstrual period. |
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The primordial follicles are immature ova which have been present since the birth of a woman. True/False
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True. While 8-12 follicles begin to develop every month only one will progress to become the mature follicle which will eventually give rise to ovulation.
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what effect does FSH have on the follicular cells?
|
The follicular or granulosa cells divide eventually forming a much larger mature follicle.
maturation of the follicle is further stimulated by estrogen, produced by the follicle itself. |
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What else does the estrogen produced by the developing follicle stimulate?
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It stimulates the development of the endometrium during the first half of the menstrual cycle.
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What does a mature follicle contain?
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It has many layers of follicular cells and an internal collection of follicular fluid. this mature follicle is a Graafian follicle. this follicle moves to lie just under the outer layer of the ovary.
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Under the influence of LH, the mature Graafian follicle ruptures. True/False
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True. The ovum is released from the follicle. this is ovulation.
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Ovulation normally occurs from alternate ovaries each month. True/false
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True. each ovary will release an ovum every two months.
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What effect does progesterone have have on the endometrium?
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High levels of progesterone, produced by the CL, and to a lesser extent estrogen, maintain the developed vascular state of the endometrium during the second half of the ovarian cycle.
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if no pregnancy occurs how soon does the CL degenerate/
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It degenerates after 12 days. As the levels of progesterone and estrogen drop, the endometrium is no longer maintained. it degenerates and sloughs away. (Functional layer).
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How is the myometrium able to contract?
|
Ejection of blood, serous fluid and the necrosed layer of endometrium is aided by prostaglandins which promote contraction of the uterine myometrium. This contraction usually give rise to pain (endometralgia)
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How long can sperm conceivably live in the female genital tract?
|
About 5 days. actual fertilization may occur several days after coitus has occurred.
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A fertilized ovum passes down the uterine tube and enters the uterus how quickly after ovulation?
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About three to four days.
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Once in the uterus, how is the ovum nourished?
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It is nourished by glycogen rich endometrial rich secretion termed uterine milk.
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For the first 3-4 months of pregnancy, how is the endometrium maintained?
|
The CL continues to secrete estrogen and progesterone which maintain the state of the endometrium. menstruation would occur, if the endometrium were not maintained in this way.
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During the early stage of pregnancy, how is the CL itself maintained?
|
It is maintained by a hormone called Human chorionic gonadotropin. It is produced by the chorion and may be detected in a pregnant woman's blood and urine as little as eight days after fertilization.
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What is the function of the chorion?
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It is one of the membranes which form the embryonic sac and later develops into part of the placenta.
The placenta permits transfer of nutrients and O2 from the maternal to the fetal blood. |
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What are the three main hormone estrogen types found in the blood?
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Estradiol, Estrone and Estriol.
Estrogens permit the development of internal organs and change the vaginal epithelium from cuboidal to a stratified squamous type which is more resistant to trauma and infection. |
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Mammary lobules are connected to a system of mammary ducts lined with columnar epithelium. True/False
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True. These ducts transport milk towards the nipple. The ductule system from the lobules converges into 15 -20 lactiferous sinuses and ducts. each duct opens up independently onto a nipple.
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Do estrogen levels have an influence on the breast tissue?
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Yes. High levels of estrogen are secreted by the placenta during pregnancy. These estrogen levels cause the lobular and ductal system of the breasts to grow and branch in preparation for milk production.
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What is the function of prolactin?
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During pregnancy, the anterior pituitary gland produces increasing amounts of prolactin which stimulates the synthesis and secretion of milk.
Milk levels start to reduce after about 8-9 months. |
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What is the function of Oxytocin?
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Oxytocin causes the contraction of myoepithelial cells which surround the alveoli and mammary ducts. Oxytocin results in contraction of alveoli resulting in the milk release. Contraction pressure can reach about 10-20 mm/Hg.
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What are the three major layers of the eye?
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1. Fibrous layer (sclera)
2.Vascular layer (has 3 continuous structures, the choroid, ciliary body and iris. 3. Retina (neurological) |
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What is the sclera?
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The sclera is a tough, fibrous, outer layer which maintains the shape of the eyeball. It is transparant at the front to let light in.
Light rays passing through the cornea are refracted. |
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Most of the extrinsic eye muscles are controlled by which nerve?
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The oculomotor nerve. This is the third cranial nerve.
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Lack of vitamin A can lead to a wrinkled dry looking conjunctiva. True/False
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True. There are also little grey bubbles called Bitot's spots. This is Xeropthalmia and lead to blindness.
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What color is the choroid?
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It is dark brown. It can absorb any reflected light. if the light from the retina was not absorbed it could reflect back onto the retina for a second time producing double images.
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Where are the Ciliary muscles?
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Ciliary musckles are attached to the suspensory ligaments which in turn attach to the capsule containing the lens.
The contraction of the ciliary muscles will reduce tension on the lens allowing it to become fatter and more convex. |
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Contraction and relaxation of the ciliary muscle changes the shape of the lens. True/False
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True. aswell, this will influence the degree to which it refracts light.
This alteration in the refractive index allows for acurate focusing of light rays passing through. These contractions are controlled by the oculomotor nerve. |
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Where is the Iris?
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This is the visible colored part of the eye which lies behind the cornea and in front of the lens. Eye color is determined by the color of the iris and is geneticaslly determined.
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In the center of the iris is the dark opening of the pupil. True/False
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True. This is the only portal through which light may enter the eyeball.
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Why does the pupil appear dark?
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There is no light emanating from within the eyeball. the light that has entered is absorbed so it does not escape from the pupil.
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How does pupil size occur?
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Within the iris are circular and radial muscle alterations in pupil size. This regulates how much light can enter the eye.
Contraction of the circular muscle fibers constrict the pupil. Contraction of the radial muscles dilates it. |
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Contraction of the iris, and the size of the pupil is controlled by which nerve?
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Cranial nerve # 3. (Oculomotor)
This nerve arises from the midbrain of the brainstem and passes along the base of the skull into the eye. |
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What occurs if the oculomotor nerve is deficient?
|
The pupil on the same side (paired nerve) will not constrict normally when a light is shone into the eye. The pupil becomes sluggish and dilated.
It may be a serious sign of some form of head injury or disease. |
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When the ciliary muscles contract, they push down on the lens causing it to become thicker. True/False
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True. Relaxation of the ciliary muscles stretches the lens making it thinner.
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Regarding light rays, what must be done in order to focus on near objects?
|
Incoming light rays must be refracted through a greater angle by a thicker lens. With distant objects, the light rays need to be refracted less so the ciliary muscles will relax allowing the lens to become thinner.
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Light rays are refracted by the lens to such a degree that they converge before the retina. True/False
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True. Light rays pass through each other without any interference and therefore images are formed upside down on the retina.
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What is a cataract?
|
If the lens develops a cloudiness or opacity, this is termed a cataract. it occurs with age, or from organic disease, such as diabetes.
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What happens to light rays if the lens is more convex?
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The more it will refract the light rays passing through. as a result of this, the light rays converge at a point in front of the retina.
though the image on the retina is upside down, the occipital lobes of the brain reverse these images allowing us to perceive the world right side up. |
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Light rays from near objects are very divergent. True/False
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True. As a result of this, they need to be refracted (bent) through a large angle in order to focus on the retina.
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What happens in the process of accommodation/
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The ciliary muscles contract causing the lens to become shorter and fatter. The surface of the lens becomes more convex and so will increase the angle through which light rays will be refracted. This permits light from close objects to be focused on the retina.
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What is Presbyopia?
|
With increasing age the lens hardens and is less able to accommodate. This makes it harder to focus on close objects resulting in the age related problem of Presbyopia. This is why reading glasses become more common in older age.
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Light rays from distant objects are more parallel. True/False
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True. This means that less refraction is required. In order to focus on distant objects the ciliary muscles relax stretching the lens causing it to become thinner.
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What is visual acuity?
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This is the ability to distinguish two separate points of light. VA is at its best when the light rays fall on the cones of the fovea.
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What is the Fovea?
|
The fovea is the central area of the retina and is densely populated with color sensitive cone cells with high levels of acuity.
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VAs can be tested with a Snellen chart. True/False
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True. This chart starts with big letters and works down to progressively smaller ones. A standard chart should be viewed from a distance of 6 meters and each eye is tested separately.
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Where is the Anterior chamber?
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It is behind the cornea and in front of the iris, while the posterior chamber is behind the iris. They are continuous through the pupillary opening.
Both chambers are filled with acqueous humor. |
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Where is the acqueous humor secreted into?
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It is secreted into the anterior chamber from the epithelium of the ciliary body. From here it flows through the pupil into the anterior chamber and is then absorbed into the Scleral venous sinus (canal of Schlemm).
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Where is the Vitreous chamber?
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It is behind the lens and in front of the retina.
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Where is the Optic disc found?
|
It is found where the optic nerve leaves the retina, as this area has no light sensitive cells. It is known as the blind spot. It is lighter in color than the surrounding retina.
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What is Papilloedema?
|
Swelling of the optic discs can be seen using an opthalmoscope and is called papiloedema.
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What is meant by detached retina?
|
It is an abnormal situation where the neural layer separates from the pigmented layer. As much of the neural nutrition is received via this layer, prolonged detachment can lead to retinal necrosis.
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Each retina contains app. how many cone cells?
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About 3 million. these cone cells generate color vision in good light levels.
Cones have low levels of sensitivity, but high levels of acuity. |
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Are all Cones alike?
|
No. There are three different types, each having a different photopigment.
These photopigments are lipoproteins which can detect the presence of red, green, or blue light. |
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What is Erythrolabe?
|
It is a photopigment. It detects red light.
Chlorolabe detects green light Cyanolabe detects blue light. Color perception is generated by the blend of the signals created by these three types of cones. |
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What is the Macula lutea?
|
It is known as the yellow spot. It is a relatively thin area of the posterior retina containing dense arrays of light sensitive cells.
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Where is the Fovea centralis located?
|
It is a small depression located in the middle of the macula lutea. It contains only cones.
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What is the most common form of color blindness/
|
It is the sex linked genetic disorder called red-green color blindness. Males are more commonly affected. They have difficulty distinguishing reds and greens.
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Rods are insensitive to color, but work well in low light. True/False
|
True. There are about 100 million rod cells per retina and they perceive shades of grey. Rods have high sensitivity but low acuity.
his is why we only see in black and white in low light levels. |
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The area of the retina at the back of the eye has a high concentration of cones. True/False
|
True. The more peripheral areas of the retina has more rods.
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briefly describe how rods work.
|
They act by light acting on a photosensitive pigment called rhodopsin(visual purple). Bright light degrades the rhodopsin, meaning the rod cells will not function. if one moves into a dark area the cones will no longer function in the reduced light levels.
as the rhodopsin in the cones has been inactivated by the bright light we will not have rod or cone function for a period of time. |
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Why is Binocular vision possible/
|
Because the two eyes are at a slight distance apart and therefore perceive an object from a slightly different angle. Because of this, the occipital lobes of the brain are able to calculate and permit us to perceive three dimensional information.
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What is the function of the Optic nerves?
|
They carry visual information in the form of electrical nerve impulses generated by the rods and cones.
Where the optic nerve leaves the eye there are no light sensitive rods and cones resulting in a blind spot. |
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Do the two optic nerves eventually meet?
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Yes. They meet under the base of the brain at a point called the optic chiasma.
They then separate and synapse in the thalamus before carrying the visual information into the occipital lobes of the brain where vision is generated. |
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In sound, what exactly is the significance of "Hertz"?
|
The rate at which a sound source vibrates is described in terms of vibrations per second or hertz. if the vocal cords are vibrating 261.63 times per second, that is a frequency of 261.63 hertz, a middle C will be generated. This would be typical of a guitar string at that hertz level.
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In music, what happens if the frequency doubles to 523.25 Hz?
|
The pitch will have moved up one musical octave to a higher C.
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Speech is a complex combination of frequencies, mostly in the 400-2,000 Hz range. True/False
|
True. People can hear sound from a frequency range of about 20 Hz up to as high as 20,000 Hz in children. This ability diminishes with age.
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What does the speed of sound depend on?
|
It varies, depending on the density of the medium it is passing through. The denser the medium, the faster the sound will travel.
Sound travels at 1500 m/s in sea water. at sea level, at 21C sound normally travels at 344 m/s or 770mph. |
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The middle air is connected to the nasopharynx by the pharyngotympanic (Eustachian) tube). True/False
|
True.
The stapes is connected to the oval window. |
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Muscles attached to the Malleus and Stapes contract for what purpose?
|
They contract to reduce the amount of vibrations which pass through the middle ear. This occurs in response to loud noises and prevents too much sound being transmitted through to the inner ear.
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Where are inner ear structures generally located?
|
They are located within the bony labyrinth of the temporal bone.
The main parts of this labyrinth are the Vestibule, Semicircular canals and the Cochlea. This interconnected bony cavity is lined with periosteum and contains a clear fluid called the perilymph. |
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The Cochlea houses the organ of hearing. True/False
|
True. This coiled structure consists of three tubes, the Scala vestibuli, Cochlear duct and Scala tympani.
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Vibrations of the oval window are caused by vibrations of the stapes. True/False
|
True. As the oval window vibrates, this causes vibrations in the perilymph of the scala vestibuli of the cochlea.
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When the oval window vibrates slowly, what effect does this have on the perilymph?
|
This would represent very low pitch sound, slow vibrations are set up in the perilymph. These travel from the oval window into the start of the scala vestibuli at the base of the cochlea.
From here the vibrations are propagated through the perilymph to the apex of the cochlea in the scala vestibuli and then back to the round window via the scala tympani. |
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Semicircular canals are essential for balance. True/False
|
True. There are three semicircular canals, each forms 2/3 of a circle. They are connected at both ends to the utricle and contain endolymph. There is a semicircular canal in each of the three planes.
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At the end of each canal is a dilated area called what?
|
Ampulla In each ampulla is a goup of hair cells with sensitive cilia projecting from the cell surfaces. These cilia project into a gelatinous mass called the cupula.
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In relation to the cupula, what happens when the head is moved?
|
When the head moves in a particular directon, the cupola is moved by the mass of endolymph in the semicircular canal. As the cupula moves, this will stimulate the ciliated hair cells which will respond by generating new nerve impulses.
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In reference to the above question, where do these nerve impulses go?
|
They travel along nerve fibers which pass through the vestibular and vestibularcochlear nerves to the brain where they are interpreted as the sensation of movement.
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What is the Saccule and Utricle?
|
Both of these are filled with endolymph. They have an area in their walls called a macula. The two macula are at right angles to each other. They have hair cells with sensory cilia which allows them to detect side to side and forward to back movement.
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Both saccule and utricle are located in the vestibulwe of the bony labyrinth. True/False
|
True. The nerve which leaves these vestibular structures is called the vestibular nerve. It merges with the Cochlear nerve to form the vestibularcochlear nerve (VIII).
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What causes motion sickness?
|
This is a form of vertigo caused by repeated stimulation of the vestibular system. It is more likely to occur when there is an incionsistency between movement and vision. (better to look out of a front window in a moving vehicle).
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When tissue cells are injured or killed, what substance is one of the first released?
|
Phospholipids from damaged cell membranes are released into the local tissues. This phopholipid is then acted on by an enzyme which occurs naturally in the tissue called phopholipase A.
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What is the function of phopholipase A?
|
It converts the phopholipids into another fatty based substance called arichadonic acid. This arichadonic acid is then acted on by another enzyme present in tissues called Cyclo-oxygenase (COX).
COX converts the arichadonic acid into a powerful group of inflammatory mediators called Prostaglandins. |
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Corticosteroids, such as Cortisone or Prednisolone are powerful inflammatory inhibiting medications. True/False
|
True. These work by inhibiting the action of phophalipase A.
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Mast cells are very similar to circulating basophils, but remained localized in their tissues. True/False
|
True. Like basophils, they contain large granules in their cytoplasm. These granules contain inflammatory mediators.
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List two inflammatory mediators.
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Bradykinin and Histamine.
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What are the five clinical features of inflammation.
|
Redness
Heat Swelling Pain Loss of function. |
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What effects do circulating inflammatory mediators have on the CNS?
|
These mediators and Cytokines influence the brain to give rise to reduced appetite, drowsiness, malaise and fever.
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Can these mediators also influence liver function?`
|
Yes.The liver can be stimulated to produce a range of proteins which are secreted into the blood.
These are referred to as "acute phase proteins" and possess some immunological functions. |
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Cite one of these acute phase proteins.
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C reactive protein. This is a commonly tested for protein as an inflammatory marker. Its increased levels are suggestive of an inflammatory response. However, it cannot specifically locate where the inflammation is occurring.
Occasionally, Fibrinogen may also be raised. |
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Strands of fibrin will also block local lymphatic vessels, preventing the spread of infection around the body. True/False
|
True.
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What is muscle guarding?
|
If there is a condition of peritonitis, the abdominal muscles will tighten to protect the painful inflammed area below.
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What are Opsonins?
|
Opsonins bind onto the surface of particular components of a pathogen, which they recognize as being foreign to the body.
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NK cells and Eosinophils are able to directly kill other cells. True/False
|
True. Eosinophils come along side foreign material and essentially destroy it.
Digestive enzymes and other toxins are released from the eosinophil onto the foreign target. These damage the cell membrane of the pathogen and this is usually sufficient to kill the cell. Eosinophils are raised in allergic and parasitic infections. |
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NK cells are large granular lymphocytes. True/False
|
True. They can act against body cells with a wide range of vuiral infections.
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How might an NK cell recognize a virally infected cell?
|
When a cell has been invaded by a virus, some viral glycoproteins appear on the surface of the cell membrane and it is these viral fragments the NK cell sare able to recognize. Once this happens, it releases a chemical called "Perforin". The cell is destroyed at this point.
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Non protein large molecules with a molecular weight mass of over 1,000, will also be antigenic if introduced into the body. True/False
|
True. The specific component of an antigen the immune system recognizes as foreign is termed an epitope. (antigenic determinant).
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Describe a small lymphocyte.
|
These have a large nucleus with only a small area of cytoplasm. In addition to being found in the blood, many are found in the lymphatic system, such as the spleen, tonsils and lymph nodes.
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It is estimated that small lymphocytes are capable of producing a 100 million different shapes of surface receptors. True/False
|
True. This is in order to recognize 100 million differe t forms of antigens.
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An individual B cell can have about how many copies of the same Ig molecule on its surface?
|
It can have about 100,000 copies of the same Ig on its surface. After contact with a specific antigen, the particular clonal group of B cells divides to produce a population.
Some of the original clonal group divide to become memory B cells and others will differentiate into a vast number of plasma cells. From these, antibodies will be produced. |
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Are t cells as specific as b cells?
|
yes.They are only able to recognize and react to a single antigen. After exposure, their numbers will be increased by clonal expansion, so they can rapidly eliminate the specific infection.
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|
What are the three types of T lymphocytes?
|
Cytotoxic T cells
Helper T cells Suppressor t cells. |
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Do T helper lymphocyte produce signal molecules?
|
Yes. They stimulate activity in other cells involved in immunity. These molecules are made up of small proteins called peptides. Their role is for one cell to communicate with other cells. They are cytokines.
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What is the function of T suppressor lymphocytes?
|
These cells limit cytotoxic T cell activity and they also inhibit antibody production. They limit the extent of the immune response.
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What are the Variable regions on antibody molecules?
|
They are different in each individual form of antibody produced by a clonal group of lymphocytes. It is the variable region which is the antigen binding site. Epitopes and the variable regions are epitopically specific.
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What is the remainder portion of the antibody below the variable region.
|
This is a constant region, which is the same in other antibodies of the same class. Amino acid variety is minimally different. This region usually defines the antibody and its class.
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What does the term titer describe?
|
This describes the levels of antibodies in the blood.
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Give some examples of attenuated vaccines.
|
Measles, Mumps and Rubella, BCG vaccine for Tbc and Yellow fever.
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What is an advantage of an attenuated vaccine?
|
It does not cause a diseased state, unless the recipient is immunocompromised. Thes3e vaccines may require a booster.
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Cite 2 examples of vaccines that are considered dead.
|
Cholera or Hepatitis A. However, they still contain epitopes that act as antigens, stimulating clonal expansion and antibody production.
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What is a toxoid vaccine?
|
These have inactivated bacterial toxins which the body recognizes as antigenic and clonal expansion is again stimulated.
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What is a BCG vaccine?
|
Bacillus Calmette–Guérin (historically Vaccin Bilié de Calmette et Guérin commonly referred to as Bacille de Calmette et Guérin or BCG) is a vaccine against tuberculosis that is prepared from a strain of the attenuated (weakened) live bovine tuberculosis bacillus, Mycobacterium bovis, that has lost its virulence in humans by being specially subcultured in a culture medium, usually Middlebrook 7H9. Because the living bacilli evolve to make the best use of the available nutrients, they become less well adapted to their traditional environment, human blood, and can no longer induce the disease when introduced into a human host. Still, they are similar enough to their wild ancestors to provide some degree of immunity against human tuberculosis. The BCG vaccine can be anywhere from 0 to 80% effective in preventing tuberculosis for a duration of 15 years; however, its protective effect appears to vary according to geography and the lab in which the vaccine strain was grown.[1]
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DNA is essentially the recipe to make the proteins of the body. True/False
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True. A sequence of a DNA molecule, which carries enough information to produce a specific protein is referred to as a gene.
The DNA which codes for the genes is part of the chromosomes, which are located inside of the cell nucleus. |
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What happens when it is time for a gene to be expressed?
|
The information is transferred from DNA into another molecule called the RNA. The RNA molecule then travels out of the nucleus to the ribosomes in the cytoplasm. Here amino acids are synthesized into the proteins coded for by the DNA information.
Genes may cary diseased segments as well. |
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What are Chromosomes?
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Chromosomes are composed of genes in the form of DNA. They also contain proteins which give the chromosomes structure.
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How many chromosomes do people have?
|
They have 46, each of which is one of a pair. twenty two of these pairs are termed autosomes, these are the non-sexed chromosomes. The final pair are gametosomes or sex chromosomes.
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What are the sex chromosomes called in a male?
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They are referred to as the X and the Y chromosomes. Females have two X chromosomes.
Everyone has 44 autosomes and 2 gametosomes. Twenty three pairs in all. |
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Individuals receive one member of each pair of chromosomes from their mother and the other from their father. True/False
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True.
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What is Down's syndrome?
|
In this condition there is usually an extra chromosome, giving a total of 47. Because the extra chromosomal material is from the 21st chromosome, the condition is now often referred to as Trisomy 21 syndrome.
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What is a Gene?
|
Genes contain a unit of genetic information which is usually described as the information required to produce one protein.
As genes are carried on the chromosomes, there is usually a copy of each gene on both of the chromosomes which comprise a homologous pair. |
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What specifically does the homologous pair of chromosomes mean?
|
Any one gene may be present in two different forms, one of each homologous pair.
The gene for eye color may code for blue or brown eyes. These different forms of a gene are called alleles. An individual may carry one gene for blue eyes and one for brown. They can produce children with either brown or blue eyes. |
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What exactly are genes composed of?
|
They are composed of DNA which is the double helix molecule arranged in a spiral.
This formation means that the two outer strands can unwind. This will allow new subunits to be added to the two open halves of the original double helix, resulting in the formation of two new complete double helix molecules. |
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DNA is able to replicate or reproduce making copies of itself. True/False
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True. It is these self replicating properties of DNA which transmits genetic information from parebnts to children.
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How is a zygote genetically formed?
|
In the process of meiosis, one chromosome from each homologous pair enters each gamete. This halves the number of chromosomes from 23 pairs to 23. At fertilization, these 23 individual chromosomes combine to form 23 pairs in the newly formed fertilized egg cell, which is the Zygote. The zygote has a full complement of its 46 chromosomes.
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Can both alleles be expressed?
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Yes. A person with group AB blood type has an allele which codes for group A on one homologous chromosome while the other one codes for group B. Both are expressed.
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When one allele is expressed and the other is not, the expressed one is dominant. True/False
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True. The unexpressed one is recessive. A recessive gene can only be expressed in the absence of a dominant gene.
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When both genes for a specific characteristic are recessive, what will occur?
|
It will usually be expressed in the person.
Blood groups A and B are dominant while the group O gene is recessive. The recessive O gene is masked by the dominant A. when both genes on the two homologous chromosomes code for group O, the person will be group O. |
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Brown eye color is dominant to blue. True/False
|
True. A person with blue eyes must have two genes for blue eyes, on each of the homologous chromosomes. (homozygous) if the genes are different on the homologous chromosome, than the person is considered heterozygous.
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What is meant by Genotype?
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All the information carried in the genes of an individual is described as the genotype.
Phenotype describes the way these genes are expressed in the individual. |
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Give an example of a disease that is Autosomal dominant inheritance.
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Huntington's chorea, is a condition which causes chronic progressive chorea(abnormal movements) and dementia. although the abnormal gene is present from the time of fertilization, it is not usually expressed until the person is in their thirties. death may occur in about 15 years from the onset of symptoms.
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HC is caused by a dominant gene which will be expressed if present. True/False
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True. if a parent carries one copy of the HC gene there will be a 50% chance that it will be incorporated in any one gamete they produce.
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Give an example that is Autosomal recessive inheritance.
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Cystic fibrosis will be used to illustrate this principle. This condition results in abnormally viscous secretions and affects about 1 in 2,000 live births. if one recessive gene for CF is present, the diseases state will not be expressed because a normal dominant gene is also present. A person with a normal and a CF gene will be disease free (i.e. the heterozygous person is phenotypically normal). However, the defective gene may be carried to future generations.
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Cystic fibrosis will only be expressed if CF genes occupy both alleles. True/False
|
True. This is more likely to happen as the result of a marriage between two heterozygous individuals. About 1 in 20 people carry the gene.
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List some other diseases that are Autosomal recessive inheritance.
|
Albinism
Phenylalanine hydroxylase deficiency (phenylketonuria) Sickle cell disease Thalassemia |
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The sex of a fertilized zygote is determined by the fertilizing sperm. True/False
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True. Both males and females both have 44 autosomes. Males have 1 X and 1 Y. Females have 2 X chromosomes.
During meiosis, the 2 sex chromosomes separate. This means that a female may only produce gametes which contain 22 autosomes and 1 X chromosome. Men can produce an X or Y chromosome. |
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What is meant by X linked inheritance?
|
genes carried on the X chromosome may be expressed differently depending on the sex of the individual. Females have 2 X chromosomes and males have only one.
Hemophilia and blue green color blindness are 2 examples of traits carried by genes on the X chromosome. These may be dominant or recessive. |
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Is there a reason why boys suffer from an X linked trait when girls are usually only carriers?
|
Yes. This is related to the physical size of the X and the Y chromosomes. The X chromosome is bigger than the Y.
There are regions of the Y chromosome which have equivalent parts compared to the X chromosome. |
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These regions of the Y chromosomes are homologous and carry the same genes as the equivalent part of the X chromosome. True/false
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True. Any genes on the rest of the X chromosome, where there is no analogous part on the Y have therefore only one chance of being represented in males.
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A normal female has 2 genes which may code for the production of factor VIII. True/False
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True. This means that if one of the genes is defected there is still a spare copy on the other chromosome.
In a male, there is only one gene for factor VIII. The equivalent site on the Y chromosome in effect, does not exist. If the gene on the X chromosome is defective, there is no back-up gene on the Y chromosome to take over production. |
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What is Hemoarthrosis?
|
It is bleeding into a joint.
Female carriers of this condtion are heterozygous and so are asymptomatic. All the factor VIII needed for normal clotting can be produced from the normal gene on the other X chromosome. A hemophiliac would only suffer if they inherit a hemophiliac gene from each parent. |
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What are dizygotic twins?
|
Two ova may be released by a potential mother in a single menstrual cycle.If both are fertilized, by two separate sperm cells, two separate zygotes will be formed. They may be of different sexes. These are fraternal or non-identical twins. Its frequency is about 12/1,000 births.
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What are monozygotic twins?
|
These develop from a single zygote. After the first mitotic divisions in the zygote, the daughter cells generated stick together. if the early daughter cells separate, they will each carry on to develop into a separate embryo. They will develop as separate infants.
These will always be of the same sex, they are genetically identical. They are practically clones of each other. This occurs about 4 in 1,000 births. |
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Dizygotic twins tend to run in the female line. True/False
|
True. if a mother is a dizygotic twin herself, she is 2.5 times more likely to give birth to dizygotic twins.
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A mutation will cause an alteration in the DNA sequence of bases. True/False
|
True. This could result in the synthesis of an abnormal protein product which will contribute to a disease process.
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It is now known that there is some DNA in the mitochondria which are located in the cytoplasm. True/False
|
True. The mtDNA is found in one circular chromosome and contains 16,500 base pairs probably coding for 37 genes.
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What do the genes in the mtDNA code for?
|
Possibly for some components in the ribosomes, RNA molecules and proteins which are part of mitochondrial structure or function.
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Give some examples of proteins coded by mtDNA.
|
These include the ones which are involved in respiration to produce ATP, in the process of oxidative phosphorylation.
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During fertilization, the sperm contributes 23 chromosomes to the zygote. However, the mitochondria in the zygote all come from the mother. True/False
|
True. None is contributed from the father.
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|
What are unipotent stem cells/
|
These are capable of developing into a single specialized cell type.
Pluripotent stem cells may develop into a few different but related cell types. Sometimes they may develop into any cell type in the body(totipotent). |
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When a stem cell divides, are all of its cells stem cells?
|
No. One is another stem cell, and the second will develop into the cell type required.
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List four tissue types which continue to have power of regeneration.
|
Epidermis, Gastrointestinal, Mucous membrane and liver.
Neurones and muscle cells have limited or no ability to regenerate after injury or disease. |
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How was the clone of "Dolly" the sheep cloned?
|
1. An ovum was harvested from an adult female sheep and the nucleus removed using micro-manipulative techniques.
2. Another nucleus from an adult sheep cell was then implanted into the vacant ovum cell. This new cell was stimulated to divide. via an electric current. 3. Mitosis then started to produce a new embryo which was then implanted into a sheep uterus where Dolly went to term and was born. |
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What are genes?
|
Genes are composed of DNA arranged as sequences of chemical bases that encode instructions for the synthesis of proteins.
These bases are called adenine, thymine, cytosine and guanine. |
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The human genome product revealed that our DNA is composed of 3.2 billion bases arranged in pairs. True/False
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True. It has been estimated that only 2-3 % of the DNA actually codes for active genes.
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What is a proteome?
|
The genome generates what is now described as the proteome. This encompasses all of the proteins contained in the body's cells.
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What are Carbohydrtaes?
|
Carbohydrates include, sugars, starch and glycogen and can be classified as monosaccharides, disaccharides and polysaccharides.
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Describe a monosaccharide.
|
They are simple, hexagonal single unit sugars with the empirical formula C6 H12 O6.
These include glucose, fructose and galactose. All sugars are broken down into monosaccharides. These are all absorbed into the hepatic portal circulation. Glucoe is the final end product of all sugars. |
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What are Disaccharides.
|
These are made up of two chemically combined simple sugar units. Sucrose is a disaccharide from sugar cane.
Other examples are lactose and maltose. Sucrose is broken down into one glucose and one fructose. |
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|
When broken down, what does lactose yield/
|
It yields one molecule of glucose and one of galactose.
Maltose is broken down into two glucose molecules. |
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What is a polysaccharide?
|
Starch is a polysaccharide, composed of long chains of chemically combined monosaccharide molecular units.
Glycogen is a starch, a polysaccharide, and is found in animal tissues. |
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What is Glucose used for?
|
It may be used in mitochondria for thwe generation of energy via the synthesis of the energy storage molecule adenosine triphosphate (ATP). It is the body's preferred food molecule.
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What happens if more glucose enters the blood than is required?
|
Some of it is synthesized into a polysaccharide called glycogen. This occurs under the influence of insulin.
Glycogen is made up of hundreds of monosaccharide units. |
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|
How much glycogen can the liver store?
|
The liver will store about 90 grams of glycogen with a further 300g in the skeletal muscles.
Once storage capacities are reached, the excess glucose is converted by liver cells into glycerol and fatty acids which are then combined to form triglycerides. |
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What happens, once triglycerides are formed/
|
These lipid molecules are transported to the adipocytes which are fat storage cells.
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|
What are the two types of fiber?
|
Water soluble and insoluble.
Water soluble is found in fruits, vegetables, nuts, lentils, peas oats and barley. Insoluble-This is composed of cellulose, hemicellulose or lignin and is present in whole grain products, such as breads, cereals and pastas. |
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Soluble fiber also slows gastric emptying. True/False
|
True. This will delay the onset of hunger. Some cholesterol is excreted in the bile and if water soluble fiber is present, this will be reabsorbed and retained by the fiber.
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|
What is the Glycemic index?
|
This index ranks food based on the effect they have on blood sugar (glucose) levels. It runs from 0-100.
If the CHO component of a food is released rapidly, resulting in a dramatic rise in the blood glucose levels, the GI will be high. |
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|
Approximately, how much protein per day does the average adult require?
|
Adults require 0.8g of protein per day per Kg of body weight.
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All proteins are composed of 20 amino acid units which are the fundamental building blocks of proteins. True/False
|
True. many of these amino acids are combined together by peptide bonds.
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|
Describe a typical protein molecule.
|
It is a highly ordered arrangement of around 400 amino acids but some larger proteins may contain many thousands.
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What ais transamination?
|
The liver is able to synthesize ten of the amino acids from other amino acids. This leaves about ten, which the liver is unable to synthesize. These are considered essential components.
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Collagen is an essential structural protein. True/False
|
True. It is found in most body organs, skin and bone.
Actin and Myosin are contractile proteins found in muscles. Proteins are required for the function of neurones. Hemoglobin, is a complex protein that transports O2 and some CO2. |
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Is Mucous a protein?
|
It is a glycoprotein and a supply of amino acids is essential for its normal production.
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|
What does the process of deamination generate?
|
It genertaes waste nitrogen which forms ammonia (NH3). As ammonia is very toxic, the liver converts it to urea for subsequent excretion, by the kidneys.
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|
What does the term, fat saturation mean?
|
It describes the number of hydrogen atoms attached to the carbon atoms in the fat molecules.
In saturated fat, all of the carbon atoms use their chemical connections (valences) to combine with hydrogen atoms. It is saturated with hydrogen. |
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|
What do monounsaturated fats contain?
|
They contain proportionately fewer hydrogen atoms and polyunsaturated fats have even fewer still.
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|
Are vegetable fats considered saturated?
|
No. They are unsaturated and tend to be liquids at room temperature.
Sunflower oil is high in polyunsaturated fatty acids (PUFAs) and Olive oil has monounsaturated fats. Fish and nuts are other sources of monounsaturated fats. |
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|
What is a trans fat?
|
Many food manufacturers choose to saturate the vegetable fats. This process is becoming less used, and has been implicated in disease.
Reheating vegetable fats causes them to become saturated. |
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|
Is there a benefit in consuming Omega 3 fats?
|
Omega 3 PUFAs are found in fish oils and nuts and may have a beneficial effect by lowering serum triglyceride levels.
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|
Can lipids be oxidized to produce energy?
|
Yes.While fats release energy more slowly than CHOs, metabolism may be maintained over a long period of time by using reserves of fat.
The majority of the body's energy reserves are held as fat in the adipocytes |
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|
A typical 70Kg adult will have about 20% fat, which stores 131,600kcal of energy. True/False
|
True.
Lipids are required for thwe synthesis of lipoproteins and a clotting factor called thromboplastin. |
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|
Which two essential fatty acids is the body unable to synthesize?
|
These are linoleic and linolenic acid.
These are necessary for the synthesis of many other fatty acids which are needed in numerous physiological processes. |
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|
Describe a lower density lipoprotein.
|
These contain more fat while higher density lipoproteins contain more protein.
The lightest forms of lipoproteins are called chylomicrons. These transport absorbed lipids from the gut. |
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|
Where do chylomicrons form?
|
They form in the epithelial cells of the small intestine to transport dietary fat. They pass through the lacteals of the villi into the lymphatic system before entering the venous blood for transport around the body.
If there are many chylomicrons in ther blood after a fatty meal, the blood plasma will have a milky appearance. |
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|
Where are VLDL's formed.
|
VLDLs are formed in the hepatocytes of the liver. They transport lipid molecules, most of which have been formed in trhe liver, to adipocytes and metabolically active cells such as those in skeletal muscle.
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Can VLDLs be converted to LDLs?
|
Yes. They are converted to LDLs when they transfer some of their triglycerides to fat storage cells.
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|
What is the function of LDLs?
|
Low density lipoproteins transport most of the cholesterol which is carried in the blood.
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|
What is Cholesterol?
|
It is a steroid alcohol and is needed for functions such as the formation of bile salts, maintenence and repair of cell membranes and the synthesis of steroid hormones. LDLs can enter specific cells where they are broken down so the cholesterol may be used in cellular biochemistry.
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|
What are HDLs?
|
These remove excess cholesterol from the blood and body cells. this is then transported to the liver where it can be broken down and partly excreted in the bile.
HDLs transport cholesterol, it is removed from the blood by the liver, high levels of HDL are associated with preventing the formation of atheroma. |
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|
Which are the most common electrolytes found in extracellular fluid?
|
Na+ and Cl-.
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|
What is the function of potassium?
|
This is an esential electrolyte, in the form of potassium. It is important for normal electrical activity in all nerve and muscle cells. It is the most common positive ion found in intracellular fluid with fairly low levels in the plasma.
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|
What can occur if K+ levels are too low or too high?
|
Potassium levels that vary can negatively affect the heart. Cardiac arrest is possible.
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|
What role does Calcium physiologically play?
|
It plays a role in muscle and nerve activity, normal blood clotting(minor role) migration of chromosomes during cell division and the movement of motile cells such as phagocytes.
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|
What are the two forms of iron available in the diet?
|
Heme and non -heme iron. Heme iron is quickly absorbed from the gut into the blood and is derived from hemoglobin and myoglobin found in fish, meat and offal, especially liver.
Non-Heme iron is derived from plant sources such as nuts, beans, peas, green vegetables and grains. It is present as well in milk and eggs. |
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|
Is non-heme iron absorbed as efficiently as heme iron?
|
No.If however, non heme iron is eaten together with vitamin C, much more is absorbed.
Some iron may be stored in the liver, spleen and bone marrow in the form of a molecule called ferritin. |
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|
Many vitamins act as cofactors for enzymes. What does this mean?
|
Cofactors are also called coenzymes, because they form chemical bonds with enzymes. In order for many enzymes to function they require a coenzyme. together the enzyme and the coenzyme facilitate and regulate biochemical reactions within a cell.
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|
Differentiate between water and fat soluble vitamins.
|
Water soluble vitamins dissolve in the body fluids and if taken in excess are quickly excreted in the urine.
Vitamins C, B, Niacin and Folic acid are water soluble. Fat soluble vitamins such as A, D, E and K, must be absorbed dissolved in lipids, which are themselves absorbed from the gut as chylomicrons. |
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|
What is a provitamin?
|
A provitamin is a substance the body is capable of converting into a vitamin. Beta carotene is such a substance.
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|
What is Xeropthalmia/
|
Deficiency of vitamin a can lead to this condition. There is progressive deposition of keratin on the cornea that leads to dryness and thickening. White plaques develop and there is corneal softening, dissolution, infection and permanent blindness.
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|
What is the difference between wet and dry Beri-Beri?
|
This is caused by a deficiency in vitamin B1.(Thiamine). In dry BB, there is adegeneration of nervous tissue called polyneuropathy. There is a feeling of heaviness and stiffness in the legs, with possible numbness.
In wet BB, there is progressive edema, beginning in the legs and spreading to the whole body. The myocardium is affected as well. |
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|
What is Riboflavin?
|
This is vitamin B2.It acts as an enzymic cofactor for several oxidative, energy releasing reactions within cells. Deficiencies can cause fissures at the corner of the mouth (Angular stomatitis). It is not broken down in cooking.
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|
What is the function of Pyridoxine?
|
This is vitamin B6. It acts as a cofactor for enzymes involved with amino acid metabolism the daily requirements increase with protein ingestion.
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|
What is Cobalamin?
|
This is vitamin B12. It is synthesized by some microorganisms in the colon, and produced from parietal cells in the stomach.
Synthesis of the nucleic acids, DNA and RNA are dependent on this vitamin. It is important for RBC maturation. deficiency causes macrocytic anemia. In Pernicious anemia the ability to absorb B12 from the gut is lost. |
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|
What is Folic acid?
|
As with vitamin B12, a deficiency of folate causes anemia with the production of abnormally large RBCs (macrocytic). Glossitis may be present as well.
Deficiency can be caused by excessive alcohol intake. Pregnant mothers are urged to take folic acid around the first 12-16 weeks of pregnancy to avoid neural tube defects such as spina bifida. This can lead to high levels of homocysteine. |
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|
What is Niacin?
|
It is actually a collective term for two related compounds called nicotinic acis and nicotinamide. It is lost when bran is lost from cereals.
It is used as a cofactor in many reactions involved in energy production. Its deficiency can cause Pellagra(rough skin). |
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|
Pellagra presents with the three Ds. What are they?
|
Dermatitis-skin exposed to the sun, with redness and cracking.
Diarhhea Dementia. |
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|
What is the function of vitamin C?
|
It is Ascorbic acid. It acts as a coenzyme and is essential for the formation of the structural protein collagen.
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|
What is vitamin E?
|
It is a collective name for eight related compounds. these compounds are called tocotrienols and tocopherol.
Its requirement increases with the increased consumption of PUFAs. |
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|
What is vitamin K?
|
It occurs in two forms. Vitamin K1 and Vitamin K2. It is synthesized by colonic bacteria. It is important for the synthesis of coagulation cofactors.
Anticoagulant drugs such as warfarin, inhibit vitamin K activity, which is why it can be used as an antidote. |
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|
Regarding vitamin K, three of the proteins present in bone forming osteoblasts, are also dependent on vitamin K acting as a cofactor. True/false
|
true.
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|
Some highly reactive O2 radicals are generated as by products of normal cellular metabolism. True/false
|
True. These include superoxide, hydrogen peroxide and other free radicals.
A radical is a part of a molecule which is very reactive, and will seek to oxidize or chemically react with other molecules in the area. |
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|
What is a calorie?
|
A calorie is defined as the amount of heat required to increase the temperature of 1 gram of water by 1 C. When referred to as dietary calories, kilocalories is used more correctly.
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|
How is energy measured/
|
It can be measured in joules (J), a thousand being a kilojoule (kJ). One kJ is equal to 0.239 Calories (C= kilo)
When used in the body, 1 gram of CHO generates 4.1 calories of energy while one gram of protein supplies 4.3 Calories. |
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|
What type of food substance is the most energy rich?
|
Fat is the most energy rich. It yields 9.4 Calories per gram. Alcohol is not a nutrient, but can yield 7 Calories per gram.
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|
What is one unit of alcohol?
|
One unit of alcohol is 10mls of pure ethanol and has about 8 grams of alcohol, making 6 Calories.
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|
Most adults have a basal metabolic requirement of about ............................
|
1800-2300 Calories per day.
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|
What happens when fats are metabolized by body cels in the absence of CHO?
|
Ketone bodies are produced from fatty acids by the liver hepatocytes. Ketone bodies may be used in the process of energy production by several different tissues.
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|
What are Ketone bodies?
|
They are actually two forms of organic acids and acetone. The acetone gives the breath a pear like fruity odor. if enough ketone bodies build up, a condition called ketosis results.
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|
Long term management of body weight is controlled by what hormone?
|
Leptin. It is produced in adipocytes. When the adipocytes have enough reserves of lipids they secrete leptin into the blood which stimulates the satiety center.
Ghrelin, is a similar hormone that stimulates appetite. Ghrelin /ˈɡrɛlɪn/[1] is a 28 amino acid hunger-stimulating peptide and hormone that is produced mainly by P/D1 cells lining the fundus of the human stomach and epsilon cells of the pancreas |
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|
Breast milk has what kind of antibodies?
|
Breast milk has IgA antibodies. These protect infants from GI infections.
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