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126 Cards in this Set
- Front
- Back
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What are the advantages of an internal skeleton over an external skeleton? |
- provides an internal framework for the body - grows with the rest of the body - it is flexible, due to the many joints - allows easy attachment of muscles |
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Which organisms have internal and external skeletons? |
- some animals such as insects have an external skeleton - some animals such as humans have an internal skeleton |
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What are endoskeletons, what are they made of, and what can they be? |
- internal skeletons - made of living tissue such as cells and blood vessels - can be made only of cartilage e.g. a shark - or made mainly of bone with some cartilage (outer ear, nose, end of long bones) |
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What do cartilage and bone both contain? |
- they are both living and contain living cells |
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What does a long bone consist of and what are their other characteristics? |
- consists of a long shaft containing bone marrow with blood vessels - at each end there is a head covered with cartilage - they are hollow, so they are stronger and lighter than solid bones |
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What can happen to cartilage and bones seeing as they are living? |
- they can be infected by bacteria and viruses - however, they are able to grow and repair themselves |
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How does a human skeleton develop? |
- skeletons start as cartilage - by the process of OSSIFICATION (the deposition of calcium and phosphates) the cartilage is slowly replaced by bone - as a teenager, cartilage at the end of limbs produces more bone - a growth spurt - eventually most cartilage is turned into bone and the skeleton stops growing - if some cartilage remains between the head and shaft, the bone and the person is still growing |
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Describe how bones can be damaged: |
- though they are very strong they can easily be broken with a sharp knock
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What happens to your bones as you age? |
- the bones of elderly people can lack calcium and phosphorus, which can result in OSTEOPOROSIS, making them prone to fractures |
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What are the different types of fractures? |
- Greenstick fracture - the bone is not completely broken - Simple fracture - bone is completely broken - Compound fracture - bones break and pierce the skin |
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Why is it dangerous to move a person in an accident? |
- may have a suspected bone fracture - broken vertebrae in the backbone can damage the spinal cord, resulting in paralysis or death |
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Describe the structure of a bone: |
- The top third contains red blood cells, the second third white blood cells and the last third platelets - the head is covered in cartilage which absorbs shock and helps bones to slide over one other - the marrow is full of living tissue and blood vessels - the shaft surrounding the bone marrow is hard, compact bone |
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What do synovial joints contain? |
- synovial joints, such as ball and socket joints and hinge joints, contain synovial fluid, a synovial membrane, ligaments and cartilage |
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What does a ball and socket joint have in comparison to a hinge joint? |
- a wider range of movement than a hinge joint, which is restricted to only an up and down movement |
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How is the forearm raised and lowered? |
- by antagonistic muscles, the biceps and the triceps - the raise the forearm, the biceps contracts and the triceps relaxes - to lower the forearm, the biceps relaxes and the triceps contracts |
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What are the different special functions of a synovial joint? |
- the synovial fluid acts as a cushion against shock and a lubricant for easy movement - a synovial membrane holds in the synovial fluid - cartilage protects the bone head - the ligaments hold the bones in place |
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What is raising and lowering the forearm an example of? |
- a lever, with the elbow acting as a fulcrum (pivot) - the effort is multiplied resulting in greater force |
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How do muscles move? |
- they CONTRACT and RELAX, they do not EXPAND |
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Label the parts of the arm: |
- the tendon is also between the bicep and radius - the ligament is between the radius and ulna - the elbow joint is a hinge joint |
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What is cartilage? |
- a soft cushioning substance which covers the end of the bones - it acts as a shock absorber and reduces the rubbing of the bone surfaces |
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Define ligament and joint: |
- ligament - holds joints together - joint - where two or more bones meet (joined by ligaments) |
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What are the 3 types of joints and give examples of where they are found in the body: |
- fixed joint in the skull - hinge joint e.g. elbow and knee - ball and socket joint e.g. shoulders, hip |
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Describe synovial joints and their functions: |
- most joints are synovial joints - they are moveable joints containing lubricating liquid called synovial fluid - they are predominant in limbs where mobility is important - ligaments help provide their stability and muscles contract to produce movement |
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Where are hinge joints found? |
- at the elbow and knee and move in only one direction |
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Where do ball and socket joints move? |
- move in 3 dimensions or directions |
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What do tendons do, what must ligaments and tendons be, and what are the pros and cons of a hip/knee joint replacement? |
- hold muscles to bones - must be slightly stretchy yet robust allow movement yet stay strong - not too much stretch so dislocation doesn't happen all the time - pros: relieves pain and enables movement - cons: is an invasive operation and general anaesthetic is dangerous |
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What do many animals need? |
- a blood circulatory system to ensure that all their cells receive enough food oxygen and to remove waste products, such as carbon dioxide |
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What happens as blood flows through arteries, veins and capillaries? |
- the blood pressure decreases - veins have valves to ensure there is no backwards blood flow - high blood pressure would damage the fragile walls of the capillaries |
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What are single and double circulatory systems? |
- single: (such as in fish) has a single blood circuit of the heart, gills and body - double: (such as in mammals) has two circuits: the heart and lungs form one (to obtain oxygen), the heart and the rest of the body form the other (to deliver oxygen to body cells) |
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What does a double and single circulatory system require? |
- requires a four-chambered heart: two atria to receive blood (from the lungs and body) and two ventricles to distribute blood (to lungs and body) - it ensures high blood pressure for efficient and fast circulation of food and oxygen - a single circulatory system needs only two chambers in the heart, one to receive and one to distribute blood |
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Describe how knowledge of the heart has developed over time: |
- in the second century, Galen knew that the heart acted as a pump and the importance of the pulse - however he thought that the liver made blood that flowed backwards and forwards - in the 17th century, William Harvey knew that blood circulated around the body, that the heart has four chambers and about the tiny vessels that today we know as capillaries |
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Define and describe the cardiac cycle: |
- it is the sequence of events as blood enters and leaves the heart - the muscles of the two atria contract together as the two ventricles relax to the receive the blood through the atrio-ventricular valves, which prevent backward flow into the atria - muscles of the two ventricles then contract together to force blood to the lungs or around the body - semi-lunar valves prevent backward flow into the ventricles |
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How is heart rate increased? |
- more muscular activity causes a greater demand for oxygen and food so heart rate therefore increases with increasing muscular activity - it's also increased by the presence of the hormone adrenalin to prepare the body for 'fight or flight' |
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What are both natural and artificial pacemakers, and how do they coordinate heart muscle contractions? |
- groups of cells in the heart form pacemakers, which control the rate of heart beat by producing a small electric current to stimulate muscle contraction - an artificial pacemaker can be placed near the heart to send an electrical signal to the heart muscle - 2 pacemakers, the sino-atrial node (SAN) and the atrio-ventricular node (AVN) generate electrical impulses to coordinate heart muscles contraction - impulses from the SAN cause the atria to contract and stimulate the AVN - impulses from the AVN cause the ventricles to contract |
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What are amoeba,what is an open circulatory system and which organisms don't have veins or arteries? |
- single celled organisms that get nutrients by diffusion - they don't have a circulatory system - when blood is moved without the aid of vessels, the organism has an open circulatory system, so they get nutrients from diffusion - insects have no veins or arteries |
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Describe in more detail Galen's theory: |
- a 2nd century greek philosopher that thought we had 2 different types of blood: - nutritive blood, made by the liver and carried through veins to organs, where it would be consumed - vital blood, made by the heart, carried vital spirits - he also thought that the heart was not a pump or a muscle by acted as a suction |
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Describe in more detail William Harvey's theory: |
- early 17th century, proved Galen wrong - calculated that the heart pumped 100 times the body's blood volume every hour, so the same blood must circulate around the body - showed that the veins contain valves so blood must travel one way to the heart - predicted the existence of capillaries but couldn't prove it until the existence of microscopes |
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What do open circulatory systems have and what do closed circulatory systems have? |
- open - NO blood vessels - closed - DO HAVE blood vessels |
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Label the diagram of the heart: |
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Describe the cardiac cycle: |
- the atria fills with blood which increases the volume of the atria - the SAN generates an electrical impulse which causes the atria to contract, decreasing volume but increasing pressure - the atrioventricular valves open, allowing the blood to flow into the ventricles and the electrical impulse travels to the AVN - the volume of the ventricles increases, the electrical impulses travel down the bundle of HIS and the purkinje fibres from the AVN which causes the muscles in the ventricles to contract - the pressure in the ventricles increases dramatically pushing the blood through the semi-lunar valves into the arteries - the ventricles relax and the atria refill with blood and another impulse is sent from the SAN |
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When can't the heart work properly? |
- when there is a hole in the wall between the 2 sides of the heart - it can be corrected by open heart surgery |
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What does a 'hole in the heart' allow and what does it cause? |
- allows blood to flow from one side of the heart to the other, so blood leaving the heart in the aorta carries less than the usual amount of oxygen, causing muscles to have less oxygen and therefore less energy - causes the mixing of oxygenated and deoxygenated blood, resulting in the arterial blood carrying less oxygen |
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How is the circulation in an unborn baby different from circulation after it's born? |
- because the lungs don't function until it is born - an unborn baby therefore doesn't need a double circulatory system - before birth, a hole exists between the two sides of the heart, which closes at birth |
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What are the consequences of having a hole in the heart and how does it reduce the amount of oxygen? |
- blood can flow directly from one side to the other, causing there to be less oxygen in the blood which causes fatigue and breathlessness - oxygenated blood flows from the left to the right atrium, which means that a smaller amount of oxygenated blood leaves the left ventricle and the body tissues receive less oxygen |
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Why can an unborn baby have a hole in the heart and not require a double circulatory system and why does the hole close so soon after birth? |
- because whilst in the womb they receive oxygen from the placenta so oxygenated blood enters the right side and flows through the hole to the left atrium, and then to the head and body - it closes because they can't receive oxygen from the mother's placenta - therefore a hole in the heart would mean blood would leak and not be oxygenated enough. |
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When can't the heart work properly (to do with valves)? |
- can't work with damaged or weak valves - they can be repaired or replaced by surgery - a heart with damaged or weak valves produces a lower blood pressure and poor circulation as blood will leak backwards |
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Explain the consequences of damaged or weak valves in the heart: |
- as people age, their heart valves may become stiff or damaged due to bacterial infections (endocarditis) - if the valves in the heart don't close properly, blood will flow backwards which leads to heart failure and not enough oxygenated blood can reach the body tissues |
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What does a blocked coronary artery do? |
- reduces the blood flow to the heart muscles but can be by-passed by transplanting a blood vessel from another part of the body |
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Explain the consequences of a blocked coronary artery: |
- if saturated fat, tobacco, fatty deposits or plaques build up in artery walls they can become too large and obstruct blood flow - in coronary arteries this means that the heart muscle doesn't get enough oxygenated blood - heart muscle cells can't respire aerobically and without enough oxygen they can't release enough energy to contract efficiently - angina or a heart attack could develop |
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How can major heart problems be corrected? |
- by transplanting donor hearts - small electrical pumps (heart assist devices) can also be used to provide extra pressure to blood leaving the heart, so allowing time for damaged muscles to recover |
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What are the obvious advantages and disadvantages of artificial pacemakers and valves? |
- keep patients alive and improve their quality of life - no problems of donor shortage or finding tissue matches - surgery carries a risk, especially the major heart surgery of a heart transplant - preventing rejection requires a lifetime use of immuno-suppressant drugs |
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What are the advantages and disadvantages of heart transplants, pacemakers and artificial valves? |
Heart Transplant: - A - saves lives, prolongs life - D - traumatic, risk of rejection by immune system, shortage of donor hearts, risk of infection Pacemakers: - A - less traumatic with no risk of rejection - D - have to be replaced, constant worry, trauma and stress of operations Artificial Valves: - A - no capillaries supplying them so no risk of rejection of transplanted valves - D - animals may have to die to meet demand - moral issues, could be faulty - risk of replacement |
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Describe some characteristics of red blood cells: |
- produced in bone marrow - contain haemoglobin that carries oxygen - bioconcave to increase surface area |
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Describe some characteristics of white blood cells: |
- part of immune system - create antibodies to destroy antigens and engulf pathogens - bigger than red blood cells |
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Describe some characteristics of plasma: |
- yellowish liquid containing electrolytes, nutrients, vitamins, hormones, clotting factors, proteins and antibodies to fight infection |
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Describe some characteristics of platelets: |
- clotting factors carried in the plasma - clot together in a process called coagulation to heal the wound and stop excessive blood loss |
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What does blood donation involve and what does a blood transfusion do? |
- involves the collection of blood from a volunteer - anti-coagulant drugs such as heparin are used and the blood group and rhesus information is recorded - a blood transfusion puts the correct blood type into the patient's blood system, replacing blood lost after an accident or operation |
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How can doctors prevent clotting and what are some people at risk of if the blood does not clot? |
- they can use drugs such as warfarin, heparin and aspirin to prevent clotting, which can block some blood vessels in some medical conditions - people with the inherited condition haemophilia are at risk of internal bleeding from the slightest knock, as the blood does not clot |
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What is the process of blood clotting called and what happens during it? |
- a cascade process as it involves many steps - when blood platelets are exposed to the air at a wound site, it triggers a complex sequence of chemical reactions, eventually leading to the formation of a meshwork of fibrin fibres (clot). |
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What does blood group A have on its surface, what blood groups can it donate to and which can receive from? |
- A-antigens and anti-B antibodies - can donate to A and AB - can receive from A and O |
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What does blood group B have on its surface, what blood groups can it donate to and which can receive from? |
- B-antigens and anti-A antibodies - can donate to B and AB - can receive from B and O |
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What does blood group AB have on its surface, what blood groups can it donate to and which can receive from? |
- A-antigens and B-antigens but no antibodies - it is a UNIVERSAL RECIPIENT - can donate to AB - can receive from A, B, AB and O |
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What does blood group O have on its surface, what blood groups can it donate to and which can receive from? |
- no antigens and anti-A and anti-B antibodies - can donate to O - can receive from O - can be given to every blood type |
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What happens if you give someone the wrong blood type? |
- a reaction called agglutination takes place when different blood groups are incompatible - when agglutinins in red blood cells and blood plasma react, the blood transfusion endangers the patient's life - the blood is forced to clot and it blocks blood vessels, becoming a fatal issue |
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How do amoeba and earthworms get oxygen and what do larger and more complex organisms have? |
- diffusion - gills or lungs as special organs for gas exchange |
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Why are amphibians restricted to their habitats? |
- they have lungs but their skin must remain moist; they are restricted to moist habitats - they have simple lungs, but use their moist, permeable skin to obtain oxygen - the permeable skin makes them susceptible to excessive water loss, which can result in death - they need a large surface area, a large supply of blood and a short diffusion pathway for gas exchange |
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Why are fish restricted to their habitats and how does a fish breathe? |
-fish gills only work in water - they obtain oxygen from water being forced over filaments - they absorb oxygen through gills located on either side of the head - the gills are made up of tiny threadlike filaments - when the fish opens its mouth, water rushes in and the oxygen passes into the blood vessels in these filaments - the water then passes out of the fish by the operculum (gill cover) |
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What does breathing in in humans depend on? |
- the contraction of the intercostal muscles (which connect the ribs) and the muscles in the diaphram - the ribs are moved up and out and the diaphram is moved downwards, causing the chest volume to increase and the pressure to decrease - the higher outside pressure causes the air to enter the lungs |
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How do humans breathe out? |
- the intercostal muscles and diaphram relax, causing the ribs to move down and inwards and the diaphram to curve upwards - the chest volume therefore decreases, which increases the pressure, forcing the air out of the lungs |
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What does the total lung capacity consist of? |
- tidal air, which is the amount of air normally breathed in and out whilst at rest - vital capacity, which is the maximum amount of air which can be exchanged - residual air, which is the amount of air which cannot be forced out of the lungs |
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How does the exchange of gases take place, how are the exchange surfaces adapted, and what can help to diagnose lung diseases? |
- by diffusion between the alveoli (bulges of air sacs) and the air in the air sacs - diffusion occurs because the oxygen concentration in the air is higher than in the deoxygenated blood capillaries around the alveoli - the exchange surfaces are adapted for efficient gas exchange as they have a large surface area and a good blood supply - they are permeable, moist and only one cell thick - readings from a spirometer are a measure of different lung capacities and the rate of air flow; they can be used to help diagnose lung diseases |
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What is Asbestosis caused by, what are the symptoms and how can it be treated? |
- environmental and industrial surroundings - caused specifically by breathing in fine asbestos fibres - the fibres are trapped in the air sacs which limits the exchange of gases by causing inflammation and scarring of lung tissue - symptoms include shortness of breath, a persistent cough, wheezing, fatigue and chest pain - there is no cure as the damage is irreversible but sufferers should stop smoking if they already do |
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What are the causes of Athsma, what are the symptoms and what are the treatments? |
- pollution yet mainly by a combination of inherited, environmental, infectious and chemical factors - symptoms include breathlessness, tight chest pain, wheezing and difficulty with breathing - treatments include inhalers (which release ventolin to widen the bronchioles and steroid tablets (to reduce inflammation) |
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What causes cystic fibrosis and how is the risk of lung cancer increased? |
- it's an inherited condition; too much mucus is produced in the bronchioles causing breathing difficulties - greatly increased by lifestyle factors such as smoking - lung cells grow rapidly, reducing the surface area available for gaseous exchange |
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What does the respiratory system in fish allow and what happens during an athsma attack? |
- allows for a through flow of water - in humans, air must go in and out of the same structures which means that chemical particles such as tars (from cigarettes) and abestosis fibres can become trapped in air sacs - during an athsma attack, the lining of airways becomes inflamed, mucus and fluid build up in airways and the muscles around the bronchioles contract, narrowing the airways |
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What is physical digestion and why is it important? |
- breaking food into smaller pieces important because: - it allows the food to pass more easily through the digestive system - it prepares the food for chemical digestion by giving it a larger surface area |
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What happens in chemical digestion? |
- in chemical digestion, carbohydrates, proteins and fats are broken down by specific enzymes in three places:
- starch (a complex carbohydrate) breaks down into glucose (a simple sugar) because of carbohydrase in the mouth - protein breaks down into amino acids because of protease in the stomach - fats break down into fatty acids and glycerol because of lipase in the small intestine |
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What do the strong stomach acids provide, what does chemical digestion require and what does the chemical breakdown of starch involve? |
- optimum conditions for protease to work - enzymes of different pH ranges 2 steps: 1. breakdown of starch (many linked units) to maltose (two linked units) 2. breakdown of maltose to glucose (one unit) |
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What do protease enzymes require and what does the gall bladder store? |
- protease enzymes, such as pepsin in the stomach, require a low pH (acidic) while other protease enzymes in the mouth and small intestine require a higher pH (alkaline) - those in the mouth require a slightly acidic/neutral pH - the gall bladder stores bile - bile is released into the small intestine to emulsify fats, increasing their surface area for efficient digestion |
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Label a diagram of the Digestive System: |
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What do food molecules need to be and what is soluble? |
- need to be able to pass through the walls of the small intestine and dissolve in the blood or lymph which means they have to be small and soluble - digested carbs and protein molecules (glucose and amino acids) are soluble - they diffuse through the walls of the small intestine and into the blood |
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What isn't soluble in water or plasma and how is the small intestine adapted? |
- digested fat molecules (fatty acids) so they would block blood vessels - they diffuse through the walls of the small intestine and into the lymph - adapted for efficient absorption of food by having an extensive system of blood capillaries and an extensive lymphatic system of lacteals which contain lymph it also has a large surface area created by: - many villi in the walls of the small intestine - many microvilli (projections) from the walls of the villi |
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Define Digestion and Absorption: |
digestion: the process by which food is broken down into absorbable nutrients absorption: the passage of nutrients from the gastro-intestinal tract into either the blood or the lymph |
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What do the mouth and teeth do when digesting food? |
mouth: teeth crush food which is physical digestion - saliva blends with food which is chemical digestion teeth: incisors have chiseled edges that cut - canines have pointed crowns that tear - premolars and molars have ridged surfaces that crush and grind - tongue |
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What is the Pharnyx and Epiglottis? |
pharynx: tube shared by the digestive and respiratory systems epiglottis: cartilage that prevents food from entering the lungs during swallowing |
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Describe the passage of food up until the small intestine: |
- a bolus enters the stomach (bolus=ball of food) - stomach acids are added and the food is ground by muscular forces - physical digestion - in the beginning of the small intestine, fluids from the gallbladder and pancreas are released - chemical digestion - peristalsis - wavelike muscular contractions that push contents along |
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List the secretions of these sources: Salivary glands, stomach, pancreas, liver (via gallbladder) and small intestine |
- saliva - gastric juice - pancreatic juice - bile - intestinal flora |
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Describe the what the parts of the small intestine are and what they do (in terms of digestion) and what the lymphatic system is: |
- villi - small intestinal projections - microvilli - microscopic hairs on the villi - all of these components make up the massive absorptive area of the intestine - the lymphatic system is a route for fluids from tissue to enter the blood - large fats and fat-soluble vitamins use the lymph system |
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In terms of homeostasis, what do the lungs, kidneys and skin do? |
- lungs - maintain O2 and CO2 levels, the brain monitors the blood and makes you breathe faster if CO2 levels are too high - kidneys - responsible for maintaining water balance and extraction of urea from blood - skin - sweat containing water and excess salts are released from the skin |
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Describe a diagram of a kidney: |
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What are the functions of the medulla, cortex, renal pelvis/artery/vein and ureter? |
- medulla - contains millions of nephrons - cortex - protective layer - renal pelvis - supports the kidney - renal artery - carries oxygenated blood to be filtered - renal vein - carries away filtered blood - ureter - carries away the waste products, collected from the medulla and taken to the bladder |
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What do kidney's filter out and what does each kidney reabsorb? |
filter: - glucose, salt, water and urea reabsorb: - all glucose, some salts, some water |
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What does the kidney turn _____ into and what does it control? |
- turns the liquid into urine which contains urea, some salts and some water - the kidney controls the amount of salt and water in the blood |
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Describe a diagram of a nephron: |
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Describe what high pressure filtration is (in the nephrons): |
- blood enters the kidney from the renal artery under high pressure - many arterioles branch off from the renal artery and one arteriole goes to each glomerulus - blood goes in to the glomerulus via the afferent arteriole and leaves in a different arteriole called the efferent arteriole - the efferent has a narrower diameter which produces a bottleneck effect - blood can't leave the glomerulus as fast as it enters, so it's under high pressure and the glomerulus' capillaries are leaky - the result is high pressure filtration |
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Describe how the nephron enables the kidney to filter out substances, reabsorb them and control the concentration of urine: |
- substances with small molecules (water, salts, urea, glucose, amino acids, vitamins and spent molecules) are filtered out of the blood - the substances pass along the tubules of the nephron dissolved in liquid that was squeezed out from the glomerulus - all useful substances are reabsorbed by selective reabsorption - the loop of Henle, the rest of the tubule and the collecting duct regulate amounts of salt and water - if blood is watery less is reabsorbed and more dilute urine is produced - if blood is not watery more is released and less but more concentrated urine is produced |
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Describe how a kidney dialysis machine works: |
- it draws out blood and a roller pump pushes the blood through to the dialyser - the partially permeable membrane separates the blood from the dialysis fluid as urea and other waste substances diffuse out of the blood into the fluid - the blood then passes through a filter and bubble trap to stop air bubbles getting into the patient's blood system - the blood then re-enters the body |
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What is broken down in the liver and where is the product then taken to? |
- excess and unwanted amino acids are broken down in the liver, forming urea, which is taken in the blood to the kidney |
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Where does blood containing waste enter the kidney? |
- blood containing waste such as urea enters the kidney by the renal artery - blood without waste leaves by the renal vein - each kidney has an outer cortex and an inner medulla - waste removed from the kidney leaves through the ureter as urine |
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Why does blood flown in the kidney under high pressure? |
- as filtration to remove wastes also takes place under high pressure - useful materials such as water, glucose and salt are reabsorbed back into the blood |
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What does each kidney have and what do they have in turn? |
- millions of microscopic kidney tubules (nephrons) where filtration takes place to form urine each nephron has: - a network of capillaries (the glomerulus) surrounded by a capsule: this forms a filtration unit - a region where some materials such as glucose are selectively reabsorbed - a region where reabsorption of some salt and water takes place (the amount depends on body demands) |
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When is a dialysis machine used and what does dialysis fluid contain? |
- when someone has kidney failure - the machine has many tubes containing blood, surrounded by a liquid - the machine acts as an artificial kidney and removes urea from blood - as urea molecules are small, they diffuse through the membrane - a dialysis machine also uses different sizes of tubes, so it slightly increases pressure during diffusion - the fluid contains sodium salts, so it is the same or slightly lower than the desired blood concentration - this maintains the sodium levels in the blood |
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What happens in the kidneys after drinking large quantities of water and what happens during and after strenuous exercise? |
- after drinking a large quantity of water, the quantity of urine produced increases and the urine concentration decreases - during strenuous exercise or in hot conditions the body produces more sweat to cool down, so the quantity of urine produced decreases and the urine concentration increases |
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How is the concentration of urea controlled? |
The pituitary gland produces the anti-diuretic hormone (ADH) which controls the concentration of urine by: - increasing the permeability of kidney tubules so that more water is reabsorbed - using a negative feedback mechanism to control ADH production |
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Describe a diagram of what happens when there is too little water in the blood: |
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Describe a diagram of what happens when there is too much water in the blood: |
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How can CO2 be toxic and what is the body more senstive to? |
- at a high concentration is toxic and must be removed from the body - more sensitive to the level of CO2 than to that of O2 - an increase in CO2 in the blood is detected by receptors in the carotid artery - nerve impulses inform the brain, which causes the rate of breathing to increase to remove more CO2 via the lungs |
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Which 4 sex hormones control the menstrual cycle and what do they do? |
- FSH (follicle stimulating hormone) stimulates an egg to develop in an ovary - LH (luteinising hormone) controls ovulation (egg release) - progesterone maintains the uterus wall - oestrogen repairs the uterus wall |
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Where are FSH and LH released from and what do negative feedback mechanisms do in the menstrual cycle? |
- from the pituitary gland in the brain - negative feedback mechanisms (which restore the situation after change) control the level of the sex hormones in the menstrual cycle - this cycle is triggered by the receptors in the hypothalamus |
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What happens if fertilisation doesn't occur, when does menstruation occur, what starts the cycle again and what happens if an egg is fertilised? |
- if it doesn't occur the levels of oestrogen and progesterone decrease - when oestrogen and progesterone are low, menstruation occurs - a message is sent to the hypothamulus that hormone levels are again low which starts the4 cycle to begin again - if an egg is fertilised the levels of progesterone remain high and no FSH is producrd, so no more eggs develop and the uterus lining does not break |
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How can fertility in humans be controlled and what do artificial sex hormones prevent? |
- by the use of artificial sex hormones by controlling egg release and implantation - the contraceptive pill prevents ovulation and fertility drugs help to ensure ovulation - artificial sex hormones prevent ovulation by making the body think it is pregnant and this inhibits FSH release - eggs in the ovary are therefore not stimulated to develop |
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Describe the 6 methods of treating infertility (the inability to produce babies): |
1. artificial insemination, where sperm are placed into the vagina by syringe 2. using FSH to stimulate egg development 3. IVF (in vitro fertilisation), where an egg is fertilised by sperm outside the body 4. egg donation, where an egg is donated from another female, then fertilised and placed inside the uterus 5. surrogacy, where a fertilised egg is placed inside a surrogate mother (another female) 6. an ovary transplant from another female |
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What do all fertility treatments increase? |
- the chances of a successful fertilisation and pregancy - this is very important for couples who feel incomplete without a family - however, not all people agree with such treatments, which are expensive for the individuals and for the NHS |
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Describe how fertility treatments have disadvantages: |
- all raise moral issues and have risks and benefits - in particular, egg donation, surrogacy and ovary transplants raise medical issues (such as rejection) as well as moral ones (for example about paternity) - some treatments are very expensive with a low rate of success - a single IVF treatment cycle costs about £6000, with an average succes rate of about 25% and the risk of multiple births and lower birth weight |
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How and why can a developing foetus be checked? |
- can be checked to see if there are any abnormalities (e.g. in its growth or genetic makeup) checking can be done by: - amniocentesis (extracting and testing cells in the amniotic fluid - chromosomal analysis (using a blood test to test cells for any chromosome abnormalities) |
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What are the issues with foetal screening? |
- using those techniques raise ethical issues: whether it is right to interfere with a natural process and whether an unborn foetus has the right to life - the techniques also carry a small risk of causing the expulsion of the foetus |
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List the 5 stages of growth and describe what happens during them: |
- Infancy - first two years of life - highest rate pf growth, gaining around 15-24cm in a year - Childhood - from 2-11 years of age, until puberty starts - growth occurs at a slower rate than during infancy - Adolescence - from 11-15 years of age, when puberty begins - growth spurt for girls aged 10-12 and boys aged 12-15 years - Maturity - males may continue to grow until the age of 18-20 years - most females reach their full adult height by age 16 years of age - Old Age - above 60-65 years - physical abilities start to deteriorate |
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What can a balanced diet and exercise do, what are extremes in height usually caused by and what grows at different rates? |
- a balanced diet (containing calcium, phosphurus, vitamin D and proteins) and regular exercise can increase growth - extremes of height are usually caused by hormone imbalance or by genes - different parts of a foetus and a baby grow at different rates, e.g. the head grows and develops earlier than the rest of the body |
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What is reguarly monitored with babies and where is the human growth hormone produced? |
- a baby's length, mass and head size are regularly monitored to give an early warning of any growth difference from normal, possibly due to malnourishment or hormone imbalance - average growth charts are used for comparison - the human growth hormone is produced by the pituitary gland and it stimulates general growth, especially in long bones |
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Why has human life expectancy increased in recent years (4) and what are the problems with this? |
- fewer deaths from industrial diseases - better housing, so there are fewer cases of diseases such as tuberculosis - a healthier diet and lifestyle - advances in modern medicine, such as antibiotics and transplants - more people living longer has many personal and national consequences, such as a longer retirement to enjoy but a bigger burden on pension funds and health services - an ageing population raises ethical questions |
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What are the 6 organs that can be donated and which organs can be fixed with which mechanical replacements? |
- kidneys - eyes (cornea) - heart - lungs - liver - pancreas (type 1 diabetes) organs fixable with mechanical replacements: - heart pacemakers - artificial hearts - artificial knee and hip joints - eye lenses |
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What are the 3 main issues with transplants? |
- all donors need to be a good tissue match and the right age and size for the recipients - living donors have to be healthy and willing to donate yet there is currently a shortage of organ donors - with most transplants there's a risk that the recipient's immune system will reject the transplant - tissue matching, matching the donor and recipient's tissue type, and immunosuppressant drugs both reduce the risk of rejection - however, these drugs increase the risk of injections |
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Why is the supply of donated organs limited and how can these problems be avoided |
- it is limited by a shortage of donors and also by restrictions of use due to the necessity of tissue matches as well as those of size and age - these problems can be avoided by using mechanical replacements - however, these have other problems such as the dependence on a power supply, the properties of materials used their large size and body reactions to 'foreign' materials |
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What can a living person donate and what must organ donations from a dead donor meet? |
- a living person can donate blood and bone marrow (as the body replaces them) and a kidney (as we can live with only one) - transplants require a suitable tissue match - organ donations from a dead donor must meet certain criteria, such as approval from the donor or relatives, and the requirement that the donor is 'brain dead' |
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Why does organ donation raise ethical issues and what are transplants at risk of? |
- organ donation, especially from dead donors, raises ethical issues to do with human rights, the acceptance of surgery on a dead body and the fact that a person's death has been necessary to supply a donor organ - transplants are at risk of being rejected by the recipient's body and so need life-long immunosuppressive drug treatment, which can lead to the body not being able to protect itself from microorganisms |
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What can people over 18 do (organ donation-wise) and how can trends be shown? |
- people over 18 years of age can ask to be put on the donor register so their organs can be used after daeth - there are long waiting lists for organs and deaths due to shortages - some countries have an 'opt out' system, which assumes that organs can be donated without asking permission - some people object to this system, saying it is against human rights - trends in transplant and survival rates can be shown by interpreting data |
