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76 Cards in this Set
- Front
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3 stages of blood clotting
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(1) vascular spasm, vasoconstriction, or intense contraction of blood vessels, (2) formation of a platelet plug and (3) blood clotting or coagulation. Once the flow of blood has been stopped, tissue repair can begin.
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step 1 of blood clot--Vasoconstriction
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Vascular spasm or Vasoconsriction: In a normal individual, immediately after a blood vessel has been cut and endothelial cells are damaged, vasoconstriction occurs, thus slowing blood flow to the area. Smooth muscle in the vessel wall goes through spasms or intense contractions that constrict the vessel. If the vessels are small, spasms compress the inner walls together and may be able to stop the bleeding completely. If the vessels are medium to large-sized, the spasms slow down immediate outflow of blood, lessening the damage but still preparing the vessel for the later steps of hemostasis. These vascular spasms usually last for about 30 minutes, long enough for the next two stages of hemostasis to take place.
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step 2 of blood clot-platlets form
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Formation of a Platelet Plug: Within 20 seconds of an injury, coagulation is initiated. Contrary to popular belief, clotting of a cut on the skin is not initiated by air or drying out, but by platelets adhering to and activated by collagen in the blood vessels endothelium. The activated platelets then release the contents of their granules, which contain a variety of substances that stimulate further platelet activation and enhance the hemostatic process.
When the lining of a blood vessel breaks and endothelial cells are damaged, revealing collagen proteins in the vessel wall, platelets swell, grow spiky extensions, and start clumping together. They start to stick to each other and the walls of the vessel. This continues as more platelets congregate and undergo these same transformations. This process results in a platelet plug that seals the injured area. If the injury is small, a platelet plug may be able to form and close it within several seconds. If the damage is more serious, the next step of blood clotting will take place. Platelets contain secretory granules. When they stick to the proteins in the vessel walls, they degranulate, thus releasing their products, which include ADP (adenosine diphosphate), serotonin, and thromboxane A2. |
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step 3 in blood clot--clotting
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A Blood Clot Forms: If the platelet plug is not enough to stop the bleeding, the third stage of hemostasis begins: the formation of a blood clot. First, blood changes from a liquid to a gel. At least 12 substances called clotting factors take part in a series of chemical reactions that eventually create a mesh of protein fibers within the blood. Each of the clotting factors has a very specific function. We will discuss just three of the substances here: prothrombin, thrombin, and fibrinogen. Prothrombin and fibrinogen are proteins that are produced and deposited in the blood by the liver.
* Prothrombin: When blood vessels are damaged, vessels and nearby platelets are stimulated to release a substance called prothrombin activator, which in turn activates the conversion of prothrombin, a plasma protein, into an enzyme called thrombin. This reaction requires calcium ions. * Thrombin: Thrombin facilitates the conversion of a soluble plasma protein called fibrinogen into long insoluble fibers or threads of the protein fibrin. * Fibrin: Fibrin threads wind around the platelet plug at the damaged area of the blood vessel, forming an interlocking network of fibers and a framework for the clot. This net of fibers traps and helps hold platelets, blood cells and other molecules tight to the site of injury, functioning as the initial clot. This temporary fibrin clot can form in less than a minute, and usually does a good job of reducing the blood flow. Next, platelets in the clot begin to shrink, tightening the clot and drawing together the vessel walls. Usually, this whole process of clot formation and tightening takes less than a half hour. The use of adsorbent chemicals, such as zeolites, and other hemostatic agents, are also being explored for use in sealing severe injuries quickly. |
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blood group ab
1.which antigens 2. can receive/donate from which other blood types |
Blood Group AB individuals have both A and B antigens on the surface of their RBCs, and their blood serum does not contain any antibodies against either A or B antigen. Therefore, a individual with type AB blood can receive blood from any group (with AB being preferable), but can only donate blood to another group AB individual. AB blood is also known as "Universal receiver."
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blood group a
1.which antigens 2. can receive/donate from which other blood types |
Blood Group A individuals have the A antigen on the surface of their RBCs, and blood serum containing IgM antibodies against the B antigen. Therefore, a group A individual can only receive blood from individuals of groups A or O (with A being preferable), and can donate blood to individuals of groups A or AB.
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blood group b
1.which antigens 2. can receive/donate from which other blood types |
Blood Group B individuals have the B antigen on their surface of their RBCs, and blood serum containing IgM antibodies against the A antigen. Therefore, a group B individual can only receive blood from individuals of groups B or O (with B being preferabe), and can donate blood to individuals of groups B or AB.
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blood group O
1.which antigens 2. can receive/donate from which other blood types |
Blood group O individuals do not have either A or B antigens on the surface of their RBCs, but their blood serum contains IgM antibodies against both A and B antigens. Therefore, a group O individual can only receive blood from a group O individual, but they can donate blood to individuals of any ABO blood group (ie A, B, O or AB). O blood is also know as "Universal donor."
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CO2 in blood
1. removal/release 2. synthesis 3. how is it transported in blood? 4. XS of co2, effect on pH 5. how does pH changes effect ventilation |
Carbon dioxide (CO2) is removed from tissues by blood and released into the air via the lungs.
Carbon dioxide is produced by cells as they undergo the processes of cellular respiration (particularly the Kreb's Cycle). The molecules are produced from carbons that were originally part of glucose. Most of the carbon dioxide combines with water and is carried in the plasma as bicarbonate ions. An excess of carbon dioxide (through exercise, or from holding ones breath) quickly shifts the blood pH to being more acidic (acidosis). Chemoreceptors in the brain and major blood vessels detect this shift and stimulate the breathing center of the brain (the medulla oblongata). Hence, as CO2 levels build up and the blood becomes more acidic, we involuntarily breathe faster, thus lowering CO2 levels and stabilizing blood pH. In contrast, a person who is hyperventilating (such as during a panic attack) will release too much CO2 and the blood will become too alkaline (alkalosis). |
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Composition of plasma:
1. site of production 2. function also, other functions plasma serves.... |
Plasma is made up of 90% water, 7-8% soluble proteins (albumin maintains bloods osmotic integrity, others clot, etc), 1% electrolytes, and 1% elements in transit. One percent of the plasma is salt, which helps with the pH of the blood. The largest group of solutes in plasma contains three important proteins to be discussed. There are: albumins, globulins, and clotting proteins.
Albumins are the most common group of proteins in plasma and consist of nearly two-thirds of them (60-80%). They are produced in the liver. The main function of albumins is to maintain the osmotic balance between the blood and tissue fluids and is called colloid osmotic pressure. In addition, albumins assist in transport of different materials, such as vitamins and certain molecules and drugs (e.g. bilirubin, fatty acids, and penicillin). Globulins are a diverse group of proteins, designated into three groups: gamma, alpha, and beta. Their main function is to transport various substances in the blood. Gamma globulins assist the body's immune system in defense against infections and illness. Clotting proteins are mainly produced in the liver as well. There are at least 12 substances, known as "clotting factors" that participate in the clotting process. One important clotting protein that is part of this group is fibrinogen, one of the main components in the formation of blood clots. In response to tissue damage, fibrinogen makes fibrin threads, which serve as adhesive in binding platelets, red blood cells, and other molecules together, to stop the blood flow. (This will be discussed in more detail later on in the chapter.) Plasma also carries Respiratory gases; CO2 in large amounts(about 97%) and O2 in small amounts(about 3%), various nutrients(glucose, fats), wastes of metabolic exchange(urea, ammonia), hormones, and vitamins. |
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02-gas exchange
1. how used in ETC 2. how is it transported? 3. how does it get released? |
Oxygen (O2) is the most immediate need of every cell and is carried throughout the body by the blood circulation. Oxygen is used at the cellular level as the final electron acceptor in the electron transport chain (the primary method of generating ATP for cellular reactions). Oxygen is carried in the blood bound to hemoglobin molecules within red blood cells. Hemoglobin binds oxygen when passing through the alveoli of the lungs and releases oxygen in the warmer, more acidic environment of bodily tissues, via simple diffusion.
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shape of RBC
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Shape
RBC'S have a shape of a disk that appears to be “caved in” or almost flattened in the middle; this is called bi-concave. This bi-concave shape allows the RBC to carry oxygen and pass through even the smallest capillaries in the lungs. This shape also allows RBCs to stack like dinner plates and bend as they flow smoothly through the narrow blood vessels in the body. RBC's lack a nucleus (no DNA) and no organelles, meaning that these cells cannot divide or replicate themselves like the cells in our skin and muscles. |
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Main Component of RBCs--Hemoglobin
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Main Component
The main component of the RBC is hemoglobin protein which is about 25 million per cell. The word hemoglobin comes from hemo meaning blood and globin meaning protein. This is the protein substance of four different proteins: polypeptide globin chains that contain anywhere from 141 to 146 amino acids. Hemoglobin also is responsible for the cell’s ability to transport oxygen and carbon dioxide. This hemoglobin + iron + oxygen interact with each other forming the RBC's bright red color. You can call this interaction by product oxyhemoglobin. Carbon Monoxide forms with hemoglobin faster that oxygen, and stays formed for several hours making hemoglobin unavailable for oxygen transport right away. Also a red blood cell contains about 200 million hemoglobin molecules. If all this hemoglobin was in the plasma rather than inside the cells, your blood would be so "thick" that the heart would have a difficult time pumping it through. The thickness of blood is called viscosity. The greater the viscosity of blood, the more friction there is and more pressure is needed to force blood through. |
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Function of RBC
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Functions
The main function is the transportation of oxygen throughout the body and the ability of the blood to carry out carbon dioxide which is called carbamino – hemoglobin. Maintaining the balance of blood is important. The balance can be measured by the acid and base levels in the blood. This is called pH. Normal pH of blood ranges between 7.35-7.45; this normal blood is called Alkaline (less acidic then water). A drop in pH is called Acidic. This condition is also called Acidosis. A jump in pH higher then 7.45 is called "Alkalosis". To maintain the homeostasis (or balance,) the blood has tiny molecules within the RBC that help prevent drops or increases from happening. |
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RBC-breakdown
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Destruction
Red blood cells are broken down and hemoglobin is released. The globin part of the hemoglobin is broken down into amino acid components, which in turn are recycled by the body. The iron is recovered and returned to the bone marrow to be reused. The heme portion of the molecule experiences a chemical change and then gets excreted as bile pigment (bilirubin) by the liver. Heme portion after being broken down contributes to the color of feces and your skin color changing after being bruised. |
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WBC-shape/where made
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White Blood Cells
Shape White blood cells are different from red cells in the fact that they are usually larger in size 10-14 micrometers in diameter. White blood cells do not contain hemoglobin which in turn makes them translucent. Many times in diagrams or pictures white blood cells are represented in a blue color, mainly because blue is the color of the stain used to see the cells. White blood cells also have nucleii, that are some what segmented and are surrounded by electrons inside the membrane. White blood cells are made in the bone marrow but they also divide in the blood and lymphatic systems. They are commonly amoeboid (cells that move or feed by means of temporary projections, called pseudopods (false feet), and escape the circulatory system through the capillary beds. |
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Platlets
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Their production is regulated by the hormone called Thrombopoietin. The circulating life of a platelet is 8–10 days. The sticky surface of the platelets allow them to accumulate at the site of broken blood vessels to form a clot. This aids in the process of hemostasis ("blood stopping"). Platelets secrete factors that increase local platelet aggregation (e.g., Thromboxane A), enhance vasoconstriction (e.g., Serotonin), and promote blood coagulation (e.g., Thromboplastin).
Platelets, also called thrombocytes, are membrane-bound cell fragments. Platelets have no nucleus, |
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WBC-granular
3 types |
Neutrophils, Eosinophils, and Basophils are all granular leukocytes.
Basophils store and synthesize histamine which is important in allergic reactions. They enter the tissues and become "mass cells" which help blood flow to injured tissues by the release of histamine. Eosinophils are chemotoxic and kill parasites. Neutrophils are the first to act when there is an infection and are also the most abundant white blood cells. Neutrophils fight bacteria and viruses by phagocytosis which mean they engulf pathogens that may cause infection. The life span of a of Neutrophil is only about 12-48 hours. |
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WBC-monocytes
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Monocytes are the biggest of the white blood cells and are responsible for rallying the cells to defend the body. Monocytes carry out phagocytosis and are also called macrophages.
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Hemolytic Disease of the Newborn
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Hemolytic Disease of the Newborn
Often a pregnant woman carries a fetus with a different blood type to herself, and sometimes the mother forms antibodies against the red blood cells of the fetus, leading to low fetal blood counts, a condition known as hemolytic disease of the newborn. Hemolytic disease of the newborn, (also known as HDN) is an alloimmune condition that develops in a fetus when the IgG antibodies produced by the mother and passing through the placenta include ones which attack the red blood cells in the fetal circulation. The red cells are broken down and the fetus can develop reticulocytosis and anemia. The fetal disease ranges from mild to very severe and fetal death from heart failure - hydrops fetalis - can occur. When the disease is moderate or severe many erythroblasts are present in the fetal blood and so these forms of the disease can be called erythroblastosis fetalis. Before birth, options for treatment include intrauterine transfusion or early induction of labor when pulmonary maturity has been attained, fetal distress is present, or 35 to 37 weeks of gestation have passed. The mother may also undergo plasma exchange to reduce the circulating levels of antibody by as much as 75%. After birth, treatment depends on the severity of the condition, but could include temperature stabilization and monitoring, phototherapy, transfusion with compatible packed red blood, exchange transfusion with a blood type compatible with both the infant and the mother, sodium bicarbonate for correction of acidosis and/or assisted ventilation. Rh negative mothers who have had a pregnancy with or are pregnant with a Rh positive infant, are given Rh immune globulin (RhIG) also known as Rhogam, during pregnancy and after delivery to prevent sensitization to the D antigen. It works by binding any fetal red cells with the D antigen before the mother is able to produce an immune response and form anti-D IgG. A drawback to pre-partum administration of RhIG is that it causes a positive antibody screen when the mother is tested which is indistinguishable from immune reasons for antibody production. |
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blood flow through heart
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The right pump pumps the blood to the lungs or the pulmonary circulation at the same time that the left pump pumps blood to the rest of the body or the systemic circulation. Venous blood from systemic circulation (deoxygenated) enters the right atrium through the superior and inferior vena cava. The right atrium contracts and forces the blood through the tricuspid valve (right atrioventricular valve) and into the right ventricles. The right ventricles contract and force the blood through the pulmonary semilunar valve into the pulmonary trunk and out the pulmonary artery. This takes the blood to the lungs where the blood releases carbon dioxide and receives a new supply of oxygen. The new blood is carried in the pulmonary veins that take it to the left atrium. The left atrium then contracts and forces blood through the left atrioventricular, bicuspid, or mitral, valve into the left ventricle. The left ventricle contracts forcing blood through the aortic semilunar valve into the ascending aorta. It then branches to arteries carrying oxygen rich blood to all parts of the body.
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ATRIUM-L and R
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Atrium
There are two atria on either side of the heart. On the right side is the atrium that contains blood which is poor in oxygen. The left atrium contains blood which has been oxygenated and is ready to be sent to the body. The right atrium receives de-oxygenated blood from the superior vena cava and inferior vena cava. The left atrium receives oxygenated blood from the left and right pulmonary veins. |
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Ventricles
1. function of L and R 2. structural differences |
Ventricles
The ventricle is a heart chamber which collects blood from an atrium and pumps it out of the heart. There are two ventricles: the right ventricle pumps blood into the pulmonary circulation for the lungs, and the left ventricle pumps blood into the systemic circulation for the rest of the body. Ventricles have thicker walls than the atria, and thus can create the higher blood pressure. Comparing the left and right ventricle, the left ventricle has thicker walls because it needs to pump blood to the whole body. This leads to the common misconception that the heart lies on the left side of the body. |
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Ventricular Septum
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Septum
The interventricular septum (ventricular septum, or during development septum inferius) is the thick wall separating the lower chambers (the ventricles) of the heart from one another. The ventricular septum is directed backward and to the right, and is curved toward the right ventricle. The greater portion of it is thick and muscular and constitutes the muscular ventricular septum. Its upper and posterior part, which separates the aortic vestibule from the lower part of the right atrium and upper part of the right ventricle, is thin and fibrous, and is termed the membranous ventricular septum. |
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Valves-Three types
1. location 2. function 3. relation in beating of heart |
Valves
The two atrioventricular (AV) valves are one-way valves that ensure that blood flows from the atria to the ventricles, and not the other way. The two semilunar (SL) valves are present in the arteries leaving the heart; they prevent blood from flowing back into the ventricles. The sound heard in a heart beat is the heart valves shutting. The right AV valve is also called the tricuspid valve because it has three flaps. It is located between the right atrium and the right ventricle. The tricuspid valve allows blood to flow from the right atrium into the right ventricle when the heart is relaxed during diastole. When the heart begins to contract, the heart enters a phase called systole, and the atrium pushes blood into the ventricle. Then, the ventricle begins to contract and blood pressure inside the heart rises. When the ventricular pressure exceeds the pressure in the atrium, the tricuspid valve snaps shut. The left AV valve is also called the bicuspid valve because it has two flaps. It is also known as the mitral valve due to the resemblance to a bishop's mitre (liturgical headdress). This valve prevents blood in the left ventricle from flowing into the left atrium. As it is on the left side of the heart, it must withstand a great deal of strain and pressure; this is why it is made of only two cusps, as a simpler mechanism entails a reduced risk of malfunction. There are two remaining valves called the Semilunar Valves. They have flaps that resemble half moons. The pulmonary semilunar valve lies between the right ventricle and the pulmonary trunk. The aortic semilunar valve is located between the ventricle and the aorta. |
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Blood Flow After The Heart
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Blood Flow After The Heart
Aorta-Arteries-Arterioles-Capillaries-Venules-Veins-Vena Cava |
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Arteries
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Arteries
Arteries are muscular blood vessels that carry blood away from the heart, oxygenated and deoxygenated blood . The pulmonary arteries will carry deoxygenated blood to the lungs and the sytemic arteries will carry oxygenated blood to the rest of the body. Arteries have a thick wall that consists of three layers. The inside layer is called the endothelium, the middle layer is mostly smooth muscle and the outside layer is connective tissue. The artery walls are thick so that when blood enters under pressure the walls can expand. |
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Arterioles
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Arterioles
An arteriole is a small artery that extends and leads to capillaries. Arterioles have thick smooth muscular walls. These smooth muscles are able to contract (causing vessel constriction) and relax (causing vessel dilation). This contracting and relaxing affects blood pressure; the higher number of vessels dilated, the lower blood pressure will be. Arterioles are just visible to the naked eye. |
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Veins
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Veins
Veins carry blood to the heart. The pulmonary veins will carry oxygenated blood to the heart awhile the systemic veins will carry deoxygenated to the heart. Most of the blood volume is found in the venous system; about 70% at any given time. The veins outer walls have the same three layers as the arteries, differing only because there is a lack of smooth muscle in the inner layer and less connective tissue on the outer layer. Veins have low blood pressure compared to arteries and need the help of skeletal muscles to bring blood back to the heart. Most veins have one-way valves called venous valves to prevent backflow caused by gravity. They also have a thick collagen outer layer, which helps maintain blood pressure and stop blood pooling. If a person is standing still for long periods or is bedridden, blood can accumulates in veins and can cause varicose veins. The hollow internal cavity in which the blood flows is called the lumen. A muscular layer allows veins to contract, which puts more blood into circulation. Veins are used medically as points of access to the blood stream, permitting the withdrawal of blood specimens (venipuncture) for testing purposes, and enabling the infusion of fluid, electrolytes, nutrition, and medications (intravenous delivery). |
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Venules
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Venules
A venule is a small vein that allows deoxygenated blood to return from the capillary beds to the larger blood veins, except in the pulminary circuit were the blood is oxygenated. Venules have three layers; they have the same makeup as arteries with less smooth muscle, making them thinner |
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The Pulmonary Circuit
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The Pulmonary Circuit
In the pulmonary circuit, blood is pumped to the lungs from the right ventricle of the heart. It is carried to the lungs via pulmonary arteries. At lungs, oxygen in the alveolae diffuses to the capillaries surrounding the alveolae and carbon dioxide inside the blood diffuses to the alveolae. As a result, blood is oxygenated which is then carried to the heart's left half -to the left atrium via pulmonary veins. Oxygen rich blood is prepared for the whole organs and tissues of the body. This is important because mitochondria inside the cells should use oxygen to produce energy from the organic compounds. |
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The Systemic Circuit
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The Systemic Circuit
The systemic circuit supplies oxygenated blood to the organ system. Oxygenated blood from the lungs is returned to the left atrium, then the ventricle contracts and pumps blood into the aorta. Systemic arteries split from the aorta and direct blood into the capillaries. Cells consume the oxygen and nutrients and add carbon dioxide, wastes, enzymes and hormones. The veins drain the deoxygenated blood from the capillaries and return the blood to the right atrium. |
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Aorta
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Aorta
The aorta is the largest of the arteries in the systemic circuit. The blood is pumped from the left ventricle into the aorta and from there it branches to all parts of the body. The aorta is an elastic artery, and as such is able to distend. When the left ventricle contracts to force blood into the aorta, the aorta expands. This stretching gives the potential energy that will help maintain blood pressure during diastole, as during this time the aorta contracts passively. |
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Superior/Inferior Vanae Cavae
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Superior Venae Cavae
The superior vena cava (SVC) is a large but short vein that carries de-oxygenated blood from the upper half of the body to the heart's right atrium. It is formed by the left and right brachiocephalic veins (also referred to as the innominate veins) which receive blood from the upper limbs and the head and neck. The azygous vein (which receives blood from the ribcage) joins it just before it enters the right atrium. [edit] Inferior Venae Cavae The inferior vena cava (or IVC) is a large vein that carries de-oxygenated blood from the lower half of the body into the heart. It is formed by the left and right common iliac veins and transports blood to the right atrium of the heart. It is posterior to the abdominal cavity, and runs along side of the vertebral column on its right side. |
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Coronary Arteries
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Heart showing the Coronary Arteries The coronary circulation consists of the blood vessels that supply blood to, and remove blood from, the heart muscle itself. Although blood fills the chambers of the heart, the muscle tissue of the heart, or myocardium, is so thick that it requires coronary blood vessels to deliver blood deep into the myocardium. The vessels that supply blood high in oxygen to the myocardium are known as coronary arteries. The vessels that remove the deoxygenated blood from the heart muscle are known as cardiac veins. The coronary arteries that run on the surface of the heart are called epicardial coronary arteries. These arteries, when healthy, are capable of auto regulation to maintain coronary blood flow at levels appropriate to the needs of the heart muscle. These relatively narrow vessels are commonly affected by atherosclerosis and can become blocked, causing angina or a heart attack. The coronary arteries are classified as "end circulation", since they represent the only source of blood supply to the myocardium: there is very little redundant blood supply, which is why blockage of these vessels can be so critical. In general there are two main coronary arteries, the left and right. • Right coronary artery • Left coronary artery Both of these arteries originate from the beginning (root) of the aorta, immediately above the aortic valve. As discussed below, the left coronary artery originates from the left aortic sinus, while the right coronary artery originates from the right aortic sinus. Four percent of people have a third, the posterior coronary artery. In rare cases, a patient will have one coronary artery that runs around the root of the aorta.
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Hepatic Veins
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Hepatic Veins
In human anatomy, the hepatic veins are the blood vessels that drain de-oxygenated blood from the liver and blood cleaned by the liver (from the stomach, pancreas, small intestine and colon) into the inferior vena cava. They arise from the substance of the liver, more specifically the central vein of the liver lobule. They can be differentiated into two groups, the upper group and lower group. The upper group of three typically arises from the posterior aspect of the liver and drain the quadrate lobe and left lobe. The lower group rise from the right lobe and caudate lobe, are variable in number, and are typically smaller than those in the upper group. None of the hepatic veins have valves. |
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"Lub Dub"
1. |
"Lub-Dub"
The first heart tone, or S1, "Lub" is caused by the closure of the atrioventricular valves, mitral and tricuspid, at the beginning of ventricular contraction, or systole. When the pressure in the ventricles rises above the pressure in the atria, these valves close to prevent regurgitation of blood from the ventricles into the atria. The second heart tone, or S2 (A2 and P2), "Dub" is caused by the closure of the aortic valve and pulmonic valve at the end of ventricular systole. As the left ventricle empties, its pressure falls below the pressure in the aorta, and the aortic valve closes. Similarly, as the pressure in the right ventricle falls below the pressure in the pulmonary artery, the pulmonic valve closes. During inspiration, negative intrathoracic pressure causes increased blood return into the right side of the heart. The increased blood volume in the right ventricle causes the pulmonic valve to stay open longer during ventricular systole. This causes an increased delay in the P2 component of S2. During expiration, the positive intrathoracic pressure causes decreased blood return to the right side of the heart. The reduced volume in the right ventricle allows the pulmonic valve to close earlier at the end of ventricular systole, causing P2 to occur earlier, and "closer" to A2. It is physiological to hear the splitting of the second heart tone by younger people and during inspiration. During expiration normally the interval between the two components shortens and the tone becomes merged. |
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SA Node
1. location 2. role in action potentials 3. control by nervous system 4. vagus nerve |
SA Node
The sinoatrial node (abbreviated SA node or SAN, also called the sinus node) is the impulse generating (pacemaker) tissue located in the right atrium of the heart. Although all of the heart's cells possess the ability to generate the electrical impulses (or action potentials) that trigger cardiac contraction, the sinoatrial node is what normally initiates it, simply because it generates impulses slightly faster than the other areas with pacemaker potential. Because cardiac myocytes, like all nerve cells, have refractory periods following contraction during which additional contractions cannot be triggered, their pacemaker potential is overridden by the sinoatrial node. The SA node emits a new impulse before either the AV or purkinje fibers reach threshold. The sinoatrial node (SA node) is a group of cells positioned on the wall of the right atrium, near the entrance of the superior vena cava. These cells are modified cardiac myocytes. They possess some contractile filaments, though they do not contract. Cells in the SA node will naturally discharge (create action potentials) at about 70-80 times/minute. Because the sinoatrial node is responsible for the rest of the heart's electrical activity, it is sometimes called the primary pacemaker. If the SA node doesn't function, or the impulse generated in the SA node is blocked before it travels down the electrical conduction system, a group of cells further down the heart will become the heart's pacemaker. These cells form the atrioventricular node (AV node), which is an area between the right atrium and ventricle, within the atrial septum. The impulses from the AV node will maintain a slower heart rate (about 40-60 beats per a minute). When there is a pathology in the AV node or purkinje fibers, an ectopic pacemaker can occur in different parts of the heart. The ectopic pacemaker typically discharges faster than the SA node and causes an abnormal sequence of contraction. The SA node is richly innervated by vagal and sympathetic fibers. This makes the SA node susceptible to autonomic influences. Stimulation of the vagus nerve causes decrease in the SA node rate (thereby causing decrease in the heart rate). Stimulation via sympathetic fibers causes increase in the SA node rate (thereby increasing the heart rate). The sympathetic nerves are distributed to all parts of the heart, especially in ventricular muscles. The parasympathetic nerves mainly control SA and AV nodes, some atrial muscle and ventricular muscle. Parasympathetic stimulation from the vagal nerves decreases the rate of the AV node by causing the release of acetylcholine at vagal endings which in turn increases the K+ permeability of the cardiac muscle fiber. Vagal stimulation can block transmission through AV junction or stop SA node contraction which is called "ventricular escape." When this happens, the purkinje fibers in the AV bundle develops a rhythm of their own. In the majority of patients, the SA node receives blood from the right coronary artery, meaning that a myocardial infarction occluding it will cause ischemia in the SA node unless there is a sufficiently good anastomosis from the left coronary artery. If not, death of the affected cells will stop the SA node from triggering the heartbeat |
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AV node
1. location 2. role in AP's 3. role in handling impulses |
AV Node
The atrioventricular node (abbreviated AV node) is the tissue between the atria and the ventricles of the heart, which conducts the normal electrical impulse from the atria to the ventricles. The AV node receives two inputs from the atria: posteriorly via the crista terminalis, and anteriorly via the interatrial septum. [1] An important property that is unique to the AV node is decremental conduction. This is the property of the AV node that prevents rapid conduction to the ventricle in cases of rapid atrial rhythms, such as atrial fibrillation or atrial flutter. The atrioventricular node delays impulses for 0.1 second before spreading to the ventricle walls. The reason it is so important to delay the cardiac impulse is to ensure that the atria are empty completely before the ventricles contract (Campbell et al, 2002). The blood supply of the AV node is from a branch of the right coronary artery in 85% to 90% of individuals, and from a branch of the left circumflex artery in 10% to 15% of individuals. In certain types of supraventricular tachycardia, a person could have two AV Nodes; this will cause a loop in electrical current and uncontrollably-rapid heart beat. When this electricity catches up with itself, it will dissipate and return to normal heart-beat speed. |
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Bundle of His
1. function 2. shape 3. what do they comprise? |
AV Bundle
The bundle of HIS is a collection of heart muscle cells specialized for electrical conduction that transmits the electrical impulses from the AV node (located between the atria and the ventricles) to the point of the apex of the fascicular branches. The fascicular branches then lead to the Purkinje fibers which innervate the ventricles, causing the cardiac muscle of the ventricles to contract at a paced interval. These specialized muscle fibers in the heart were named after the Swiss cardiologist Wilhelm His, Jr., who discovered them in 1893. Cardiac muscle is very specialized, as it is the only type of muscle that has an internal rhythm; i.e., it is myogenic which means that it can naturally contract and relax without receiving electrical impulses from nerves. When a cell of cardiac muscle is placed next to another, they will beat in unison. The fibers of the Bundle of HIS allow electrical conduction to occur more easily and quickly than typical cardiac muscle. They are an important part of the electrical conduction system of the heart as they transmit the impulse from the AV node (the ventricular pacemaker) to the rest of the heart. The bundle of HIS branches into the three bundle branches: the right left anterior and left posterior bundle branches that run along the intraventricular septum. The bundles give rise to thin filaments known as Purkinje fibers. These fibers distribute the impulse to the ventricular muscle. Together, the bundle branches and purkinje network comprise the ventricular conduction system. It takes about 0.03-0.04s for the impulse to travel from the bundle of HIS to the ventricular muscle. It is extremely important for these nodes to exist as they ensure the correct control and co-ordination of the heart and cardiac cycle and make sure all the contractions remain within the correct sequence and in sync. |
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Purkinje Fibers
1. location 2. how does it help control heart rate? |
Purkinje Fibers
Purkinje fibers (or Purkyne tissue) are located in the inner ventricular walls of the heart, just beneath the endocardium. These fibers are specialized myocardial fibers that conduct an electrical stimulus or impulse that enables the heart to contract in a coordinated fashion. Purkinje fibers work with the sinoatrial node (SA node) and the atrioventricular node (AV node) to control the heart rate. During the ventricular contraction portion of the cardiac cycle, the Purkinje fibers carry the contraction impulse from the left and right bundle branches to the myocardium of the ventricles. This causes the muscle tissue of the ventricles to contract and force blood out of the heart — either to the pulmonary circulation (from the right ventricle) or to the systemic circulation (from the left ventricle). They were discovered in 1839 by Jan Evangelista Purkinje, who gave them his name. |
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Blood Pressure
1. Systolic 2. Diastolic |
Blood Pressure
Blood pressure is the pressure exerted by the blood on the walls of the blood vessels. Unless indicated otherwise, blood pressure refers to systemic arterial blood pressure, i.e., the pressure in the large arteries delivering blood to body parts other than the lungs, such as the brachial artery (in the arm). The pressure of the blood in other vessels is lower than the arterial pressure. Blood pressure values are universally stated in millimeters of mercury (mmHg). The systolic pressure is defined as the peak pressure in the arteries during the cardiac cycle; the diastolic pressure is the lowest pressure (at the resting phase of the cardiac cycle). The mean arterial pressure and pulse pressure are other important quantities. Typical values for a resting, healthy adult are approximately 120 mmHg systolic and 80mm Hg diastolic (written as 120/80 mmHg), with individual variations. These measures of blood pressure are not static, but undergo natural variations from one heartbeat to another, and throughout the day (in a circadian rhythm); they also change in response to stress, nutritional factors, drugs, or disease. [edit] Systolic Pressure Systolic Pressure is the highest when the blood is being pumped out of the left ventricle into the aorta during ventricular systole. The average high during systole is 120 mmHg. [edit] Diastolic Pressure Diastolic blood pressure lowers steadily to an average low of 80 mmHg during ventricular diastole |
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Lymphatic/Circulatory Homeostatic Control
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The Lymphatic System
The lymphatic system is closely related to the cardiovascular system. There are three main ways that they work together to maintain homeostasis: the lymphatic system receives the excess tissue fluid and returns it to the bloodstream, lacteals take fat molecules from the intestinal villi and transport them to the bloodstream and both systems work together to defend the body against disease. |
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Lymph
1. origin 2. process of filtration |
Lymph
Lymph originates as blood plasma that leaks from the capillaries of the circulatory system, becoming interstitial fluid, filling the space between individual cells of tissue. Plasma is forced out of the capillaries by hydrostatic pressure, and as it mixes with the interstitial fluid, the volume of fluid accumulates slowly. Most of the fluid is returned to the capillaries by osmosis. The proportion of interstitial fluid that is returned to the circulatory system by osmosis is about 90% of the former plasma, with about 10% accumulating as overfill. The excess interstitial fluid is collected by the lymphatic system by diffusion into lymph capillaries, and is processed by lymph nodes prior to being returned to the circulatory system. Once within the lymphatic system the fluid is called lymph, and has almost the same composition as the original interstitial fluid. |
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Red Bone Marrow
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* Red bone marrow, the soft, spongy, nutrient rich tissue in the cavities of certain long bones, is the organ that is the site of blood cell production.
Some of the white blood cells produced in the marrow are: neutrophils, basophils, eosinophils, monocytes, and lymphocytes. Lymphocytes differentiate into B lymphocytes and T lymphocytes. Red bone marrow is also the site of maturation of B lymphocytes. |
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Primary Lymphatic Organs
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The primary lymphatic organs are the red bone marrow and the thymus. They and are the site of production and maturation of lymphocytes, the type of white blood cell that carries out the most important work of the immune system.
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Thymus Gland
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* Thymus Gland The thymus gland is located in the upper thoracic cavity posterior to the sternum and anterior to the ascending aorta. The thymus is an organ that is more active in children, and shrinks as we get older. Connective tissue separates the thymus into lobules, which contain lymphocytes. Thymic hormones such as thymosin are produced in the thymus gland. Thymosin is thought to aid in the maturation of T lymphocytes. The Thymus is critical to the immune system. Without a thymus, a person has no ability to reject foreign substances, blood lymphocyte level is very poor, and the body’s response to most antigens is either absent or very weak
Immature T lymphocytes travel from the bone marrow through the bloodstream to reach the thymus. Here they mature and for the most part, stay in the thymus. Only 5% of T lymphocytes ever leave the thymus. They only leave if they are able to pass the test: if they react with “self” cells, they die. If they have the potential to attack a foreign cell, they leave the thymus. |
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Spleen
1. function 2. compartments 3. red/white pulp |
The spleen, The spleen is a ductless, vertebrate gland that is closely associated with the circulatory system, where it functions in the destruction of old red blood cells in holding a reservoir of blood.located in the upper left region of the abdominal cavity, is divided into partial compartments. Each compartment contains tissue known as white pulp and red pulp. The white pulp contains lymphocytes and the red pulp acts in blood filtration. When blood enters the spleen and flows through the sinuses for filtration, lymphocytes react to pathogens , macrophages engulf debris, and also remove old, worn out red blood cells. A person without a spleen is more susceptible to infections and may need supplementary antibiotic therapy for the rest of their life.
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Lymph node
1. components 2. function |
Lymph Nodes are small oval shaped structures located along the lymphatic vessels. They are about 1-25 mm in diameter. Lymph nodes act as filters, with an internal honeycomb of connective tissue filled with lymphocytes that collect and destroy bacteria and viruses. They are divided into compartments, each packed with B lymphocytes and a sinus. As lymph flows through the sinuses, it is filtered by macrophages whose function is to engulf pathogens and debris. Also present in the sinuses are T lymphocytes, whose functions are to fight infections and attack cancer cells. Lymph nodes are in each cavity of the body except the dorsal cavity. Physicians can often detect the body’s reaction to infection by feeling for swollen, tender lymph nodes under the arm pits and in the neck, because when the body is fighting an infection, these lymphocytes multiply rapidly and produce a characteristic swelling of the lymph nodes.
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B cells-antibodies
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B Cells Produce Antibodies
B cell lymphocytes are responsible for antibody-mediated immunity (humoral immunity). They produce antibodies, which are proteins that bind with and neutralize specific antigens. Antibodies do not directly kill bacteria, but mark them for destruction. When antibodies bind to viruses they can prevent the viruses from infecting cells. When antibodies bind to toxins they can neutralize the toxin (why we get immunized against the tetanus toxin). Humoral immunity works best fighting against target viruses, bacteria, and foreign molecules that are soluble in blood and lymph before the bacteria or viruses have entered into cells (extracellular bacteria and extracellular viruses). |
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B Plasma Cells
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B cells produce two different types of cells:
* plasma cells * memory cells Plasma cells As B cells mature during embryonic development, they develop surface receptors that allow them to recognize specific antigens. Then they travel in the bloodstream, distributing throughout the lymph nodes, spleen, and tonsils. Once B cells reach their destination, they remain inactive until they encounter a foreign cell with an antigen that matches their particular receptor site (most B cells remain inactive for your entire life). The foreign antigen can be presented to the B cell directly, but usually macrophages and T cell lymphocytes (helper T cells) interact with B cells as Antigen Presenting Cells to bring about antibody production. Upon such an encounter, the B cell's receptors will bind to the antigen. The appropriate B cell is turned on or stimulated. It then grows bigger, and rapidly multiplies into a large homogenous group (clone). Most of these cells are plasma cells, which actively secrete antibody that will bind with the original stimulating antigen . While most of the B cells remain in the lymphatic system, the antibodies are secreted into the lymph fluid which then enters into the blood plasma to circulate throughout the body. Although the clone cells only live a few days, their antibodies remain and circulate in the blood and lymph, gradually decreasing in number. Antibody Structure and Function There are different classes of antibodies, or immunoglobulins (Ig), such as IgA, IgG, IgE, and IgM. They can attach to the surface of a microbe and make it more easily phagocytized by neutrophils, monocytes and macrophages. Anything that simplifies phagocytosis is called an opsonin. The process of antibodies attaching to invaders can be termed 'opsonization.' Some antibodies can bind and inactivate certain poisons or toxins and are called antitoxins (tetanus immunizations stimulate your body to produce antibodies against the tetanus toxin rather than against the bacteria that produces the toxin). Still other antibodies can bind to the surface of microbes and prevent their attachment to the body's cells (thus preventing viruses from entering host cells). Also, some of them can stimulate nine proteins found in plasma, called complement. |
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B Memory Cells
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Memory B cells
At the time of activation some of the clones become memory B cells. These cells are long lived and have recorded the information about the foreign antigen so antibodies can be made more quickly, and in greater amount, in case a second exposure should occur. Since the second response is much stronger than the first and puts more antibodies into circulation, we often receive "booster shots" for immunizations. |
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How do T Cells Attack Infected Cells?
1. what kind of immunity? 2. how does crap get to the T cells 3. cytotoxic T, helper T, suppressor T |
T Cells Attack Infected Cells
Defending the body against intracellular pathogens is the role of T lymphocytes, which carry out cell-mediated immunity(CMI). Macrophages phagocytize invading microbes and present parts of the microbe (antigens) to the T cell lymphocytes. The appropriate T cell is turned on or stimulated. The activated T cell rapidly multiplies into a large homogenous group (clone) of cytotoxic T cells (Tc cells). * (a) Attack organisms directly, Also kill infected cells These cytotoxic T cells migrate to the site of infection (or disease) and produce chemicals which directly kill the invader. Cytotoxic T cells release “perforin” that causes pores to form in the plasma membrane of the target cell, resulting in lysis. * (b) T cells develop in the thymus gland from immature precursor cells that migrate there from the bone marrow. * (c) Killer and helper T cells * (d) Memory T Cells A portion of these activated T cells become memory T cells (Tm). These cells record the information about the foreign antigen so T cells can respond more quickly, and more strongly, if a second exposure occurs. A portion of the T cells become T helper cells (TH) or T suppressor cells (Ts). TH cell stimulate other T cells and B cells by releasing cytokines and other stimulatory chemicals. Ts cells suppress the immune response. Experience has shown that cell mediated immunity is most useful to the body by: Protecting against microbes which exist inside of our body's cells (intracellular bacteria and intracellular viruses). Protecting against fungal infections. Protecting against protozoan parasites. Protecting against cancer cells. |
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Active Immunity
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Acquired Immunity: Antigen-specific Responses
Acquired immunity responses are antigen-specific responses in which the body recognizes a foreign substance and selectively reacts to it. This is mediated primarily by lymphocytes. Acquired immunity overlaps with the process of innate immunity. Acquired immunity can be subdivided into active immunity and passive immunity. Active Immunity occurs when the body is exposed to a pathogen and produces its own antibodies. Active immunity is active because it is the "activation" of your immune system. Active immunity can occur naturally, when a pathogen invades the body, or artificially, like when we are given vaccinations containing disabled or killed pathogens. The body does require prior exposure to an antigen to develop an active immunity. Some parents expose their children to some antigens so they will have immunity to these diseases later in life. |
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Passive Immunity
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Acquired immunity responses are antigen-specific responses in which the body recognizes a foreign substance and selectively reacts to it. This is mediated primarily by lymphocytes. Acquired immunity overlaps with the process of innate immunity. Acquired immunity can be subdivided into active immunity and passive immunity.
Passive Immunity occurs when we acquire antibodies made by another human or animal. Passive immunity is passive because it requires no response from the person's immune system. In passive immunity you are not presenting the body with foreign antigens. Therefore your immune system will not need to use B cells, and we know that if the B cells are never introduced your body isn't making antibodies and it isn't making memory B cells. The transfer of antibodies from mother to fetus across the placenta is one example. Injections containing antibodies are another. Sometimes travelers going abroad may be injected with gamma globulin, but this passive immunity last only about three months. Passive immunizations are used to protect people who have been exposed to infections or toxins, like snake venom or tetanus. |
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cytotoxic t
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(Tc cells) destroy virally infected cells and tumor cells, and are also implicated in transplant rejection. These cells are also known as CD8+ T cells, since they express the CD8 glycoprotein at their surface.
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regulator t
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Regulatory T cells (Treg cells), formerly known as suppressor T cells, are crucial for the maintenance of immunological tolerance. Their major role is to shut down T cell mediated immunity towards the end of an immune reaction and to suppress auto-reactive T cells that escaped the process of negative selection in the thymus. Two major classes of regulatory T cells have been described, including the naturally occurring Treg cells and the adaptive Treg cells
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memory t
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Memory T cells are a subset of antigen-specific T cells that persist long-term after an infection has resolved. They quickly expand to large numbers of effector T cells upon re-exposure to their cognate antigen, thus providing the immune system with "memory" against past infections. Memory cells may be either CD4+ or CD8+.
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helper t
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Helper T cells, (Th cells) are the "middlemen" of the adaptive immune system. Once activated, they divide rapidly and secrete small proteins called cytokines that regulate or "help" the immune response. These cells (also called CD4+ T cells) are a target of HIV infection; the virus infects the cell by using the CD4 protein to gain entry. The loss of Th cells as a result of HIV infection leads to the symptoms of AIDS.
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Inhalation
1. initiation 2. how do the thorax/intrapleural cavity/alveoli/diaphragm interact? 3. Pressure of atm and alveloi |
Inspiration
Inspiration is initiated by contraction of the diaphragm and in some cases the intercostals muscles when they receive nervous impulses. During normal quiet breathing, the phrenic nerves stimulate the diaphragm to contract and move downward into the abdomen. This downward movement of the diaphragm enlarges the thorax. When necessary, the intercostal muscles also increase the thorax by contacting and drawing the ribs upward and outward. The active increase of the thorax changes the stability set up in a resting lung. As the thoracic wall moves away from lung which increases the space between the thoracic wall and lung and decreases the pressure in the intrapleural cavity. This decrease in pressure causes the pressure in the alveoli to become greater than the elastic recoil that is inherent in lung tissue. Thus, when contraction of the diaphragm and the intercostal muscles actively increase the size of the thorax, the lungs are passively forced to expand. This expansion increases the size of the alveoli which decreases pressure in the alveoli. Pressure within the alveoli is now lower than atmospheric pressure which allows air to move into the lungs through the structures discussed above. |
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Exhalation
1. passive/active 2. how do alveoli inhibit inhaltion? 3. pressure interactions.. |
Expiration
During quiet breathing, expiration is normally a passive process and does not require muscles to work. When the lungs are stretched and expanded, stretchy receptors within the alveoli send inhibitory nerve impulses to the medulla oblongata, causing it to stop sending signals to the rib cage and diaphragm to relax and rise. This elastic recoil causes the lungs and chest cavity to shrink and increase the air pressure within the lungs. This increased positive air pressure pushes the air out of the lungs. Expiration happens as the diaphragm relaxes. Although the respiratory system is primarily under involuntary control, and regulated by the medulla oblongata, we have some voluntary control over it also. This is due to the higher brain function of the cerebral cortex. |
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Upper Resp. Tract
1. components 2. function 3. path of air 4. cilia |
Upper Respiratory Tract
The upper respiratory tract consists of the nose and the pharynx. Its primary function is to receive the air from the external environment and filter, warm, and humidify it before it reaches the delicate lungs where gas exchange will occur. Air enters through the nostrils of the nose and is partially filtered by the nose hairs, then flows into the nasal cavity. The nasal cavity is lined with epithelial tissue, containing blood vessels, which help warm the air; and secrete mucous, which further filters the air. The endothelial lining of the nasal cavity also contains tiny hairlike projections, called cilia. The cilia serve to transport dust and other foreign particles, trapped in mucous, to the back of the nasal cavity and to the pharynx. There the mucus is either coughed out, or swallowed and digested by powerful stomach acids. After passing through the nasal cavity, the air flows down the pharynx to the larynx. |
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Lower Respiratory Tract
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Lower Respiratory Tract
The lower respiratory tract starts with the larynx, and includes the trachea, the two bronchi that branch from the trachea, and the lungs themselves. This is where gas exchange actually takes place. |
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Lower Respiratory Tract: Larynx
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1. Larynxľ
The larynx (plural larynges), colloquially known as the voice box, is an organ in our neck involved in protection of the trachea and sound production. The larynx houses the vocal cords, and is situated just below where the tract of the pharynx splits into the trachea and the esophagus. The larynx contains two important structures: the epiglottis and the vocal cords. The epiglottis is a flap of cartilage located at the opening to the larynx. During swallowing, the larynx (at the epiglottis and at the glottis) closes to prevent swallowed material from entering the lungs; the larynx is also pulled upwards to assist this process. Stimulation of the larynx by ingested matter produces a strong cough reflex to protect the lungs. Note: choking occurs when the epiglottis fails to cover the trachea, and food becomes lodged in our windpipe. |
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External gas exchange
1. structures involved 2. gas diffusion 3. conversion of 02/co2=effect on pH 4. De-oxy/oxy blood partial pressures |
External Respiration
External respiration is the exchange of gas between the air in the alveoli and the blood within the pulmonary capillaries. A normal rate of respiration is 12-25 breaths per minute. In external respiration, gases diffuse in either direction across the walls of the alveoli. Oxygen diffuses from the air into the blood and carbon dioxide diffuses out of the blood into the air. Most of the carbon dioxide is carried to the lungs in plasma as bicarbonate ions (HCO3-). When blood enters the pulmonary capillaries, the bicarbonate ions and hydrogen ions are converted to carbonic acid (H2CO3) and then back into carbon dioxide (CO2) and water. This chemical reaction also uses up hydrogen ions. The removal of these ions gives the blood a more neutral pH, allowing hemoglobin to bind up more oxygen. De-oxygenated blood "blue blood" coming from the pulmonary arteries, generaly has an oxygen partial pressure (pp) of 40 mmHg and CO pp of 45 mmHg. Oxygenated blood leaving the lungs via the pulmonary veins has a O2 pp of 100 mmHg and CO pp of 40 mmHg. It should be noted that alveolar O2 pp is 105 mmHg, and not 100 mmHg. The reason why pulmonary venous return blood has a lower than expected O2 pp can be explained by "Ventilation Perfusion Mismatch". |
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Stimulus for Breathing
1. 2 pathways-brain structures 2. Chemoreceptors: what does and does not influence these? 3. how is this voluntary and involuntary? |
There are two pathways of motor neuron stimulation of the respiratory muscles. The first is the control of voluntary breathing by the cerebral cortex. The second is involuntary breathing controlled by the medulla oblongata.
There are chemoreceptors in the aorta, the carotid arteries, and in the medulla oblongata of the brainstem that are sensitive to pH. As carbon dioxide levels increase there is a buildup of carbonic acid, which releases hydrogen ions and lowers pH. Thus, the chemoreceptors do not respond to changes in oxygen levels (which actually change much more slowly), but to pH, which is an indirect measure of carbon dioxide levels. In other words, CO2 is the driving force for breathing. The receptors in the aorta and the carotid arteries stimulate an immediate increase in breathing rate and the receptors in the medulla stimulate a sustained increase in breathing until blood pH returns to normal. This response can be experienced by running a 100 meter dash. During this exertion (or any other sustained exercise) your muscle cells must metabolize ATP at a much faster rate than usual, and thus will produce much higher quantities of CO2. The blood pH drops as CO2 levels increase, and you will involuntarily increase breathing rate very soon after beginning the sprint. You will continue to breathe heavily after the race, thus expelling more carbon dioxide, until pH has returned to normal. |
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Regulation of Blood pH
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Many of us are not aware of the importance of maintaining the acid/base balance of our blood. It is vital to our survival. Normal blood pH is set at 7.4, which is slightly alkaline or "basic". If the pH of our blood drops below 7.2 or rises above 7.6 then very soon our brains would cease functioning normally and we would be in big trouble. Blood pH levels below 6.9 or above 7.9 are usually fatal if they last for more than a short time. Another wonder of our amazing bodies is the ability to cope with every pH change – large or small. There are three factors in this process: the lungs, the kidneys and buffers.
So what exactly is pH? pH is the concentration of hydrogen ions (H+). Buffers are molecules which take in or release ions in order to maintain the H+ ion concentration at a certain level. When blood pH is too low and the blood becomes too acidic (acidosis), the presence of too many H+ ions is to blame. Buffers help to soak up those extra H+ ions. On the other hand, the lack of H+ ions causes the blood to be too basic (alkalosis). In this situation, buffers release H+ ions. Buffers function to maintain the pH of our blood by either donating or grabbing H+ ions as necessary to keep the number of H+ ions floating around the blood at just the right amount. The most important buffer we have in our bodies is a mixture of carbon dioxide (CO2) and bicarbonate ion (HCO3). CO2 forms carbonic acid (H2CO3) when it dissolves in water and acts as an acid giving up hydrogen ions (H+) when needed. HCO3 is a base and soaks up hydrogen ions (H+) when there are too many of them. In a nutshell, blood pH is determined by a balance between bicarbonate and carbon dioxide. Bicarbonate Buffer System. With this important system our bodies maintain homeostasis. (Note that H2CO3 is Carbonic Acid and HCO3 is Bicarbonate) CO2 + H2O <---> H2CO3 <---> (H+) + HCO3 * If pH is too high, carbonic acid will donate hydrogen ions (H+) and pH will drop. * If pH is too low, bicarbonate will bond with hydrogen ions (H+) and pH will rise. Too much CO2 or too little HCO3 in the blood will cause acidosis. The CO2 level is increased when hypoventilation or slow breathing occurs, such as if you have emphysema or pneumonia. Bicarbonate will be lowered by ketoacidosis, a condition caused by excess fat metabolism (diabetes mellitus). Too much HCO3 or too little CO2 in the blood will cause alkalosis. This condition is less common than acidosis. CO2 can be lowered by hyperventilation. So, in summary, if you are going into respiratory acidosis the above equation will move to the right. The body's H+ and CO2 levels will rise and the pH will drop. To counteract this the body will breathe more and release H+. In contrast, if you are going into respiratory alkalosis the equation will move to the left. The body's H+ and CO2 levels will fall and the pH will rise. So the body will try to breathe less to release HCO3. You can think of it like a leak in a pipe: where ever there is a leak, the body will "fill the hole". |
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Embryonic Pulmonary Circulation
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Embryonic
The pulmonary circulation loop is virtually bypassed in fetal circulation. The fetal lungs are collapsed, and blood passes from the right atrium directly into the left atrium through the foramen ovale, an open passage between the two atria. When the lungs expand at birth, the pulmonary pressure drops and blood is drawn from the right atrium into the right ventricle and through the pulmonary circuit. Over the course of several months, the foramen ovale closes, leaving a shallow depression known as the fossa ovalis in the adult heart. |
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Pulmonary Circulation Pathway: Right atrium
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[edit] Right heart
Oxygen-depleted blood from the body leaves the systemic circulation when it enters the right heart, more specifically the right atrium through the superior vena cava. The blood is then pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle. [edit] Arteries From the right ventricle, blood is pumped through the pulmonary semilunar valve into the pulmonary artery. This blood enters the two pulmonary arteries (one for each lung) and travels through the lungs. |
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Pulmonary Circulation Pathway: Veins
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[edit] Veins
The oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. This blood then enters the left atrium, which pumps it through the bicuspid valve, also called the mitral or left atrioventricular valve, into the left ventricle. The blood is then distributed to the body through the systemic circulation before returning again to the pulmonary circulation. |
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Pulmonary Circulation Pathway: Arteries
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Arteries
From the right ventricle, blood is pumped through the pulmonary semilunar valve into the pulmonary artery. This blood enters the two pulmonary arteries (one for each lung) and travels through the lungs. |
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Pulmonary Circulation Pathway: Lungs
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[edit] Lungs
The pulmonary arteries carry blood to the lungs, where red blood cells release carbon dioxide and pick up oxygen during respiration. Exchanges carbon dioxide for oxygen in the lungs. |
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Pulmonary Circulation Pathway
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The veins bring waste-rich blood back to the heart, entering the right atrium throughout two large veins called vena cavae. The right atrium fills with the waste-rich blood and then contracts, pushing the blood through a one-way valve into the right ventricle. The right ventricle fills and then contracts, pushing the blood into the pulmonary artery which leads to the lungs. In the lung capillaries, the exchange of carbon dioxide and oxygen takes place. The fresh, oxygen-rich blood enters the pulmonary veins and then returns to the heart, re-entering through the left atrium. The oxygen-rich blood then passes through a one-way valve into the left ventricle where it will exit the heart through the main artery, called the aorta. The left ventricle's contraction forces the blood into the aorta and the blood begins its journey throughout the body.
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Renal Circulation
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During systemic circulation, blood passes through the kidneys. This phase of systemic circulation is known as renal circulation. During this phase, the kidneys filter much of the waste from the blood. Blood also passes through the small intestine during systemic circulation. This phase is known as portal circulation. During this phase, the blood from the small intestine collects in the portal vein which passes through the liver. The liver filters sugars from the blood, storing them for later.
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Portal Venous system
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Portal venous system
From Wikipedia, the free encyclopedia Jump to: navigation, search This article discusses the portal venous systems in general. For the system involving the liver, see Hepatic portal system. In the circulatory system of animals, a portal venous system occurs when a capillary bed drains into another capillary bed through veins. Both capillary beds and the blood vessels that connect them are considered part of the portal venous system. They are relatively uncommon as the majority of capillary beds drain into the heart, not into another capillary bed. Portal venous systems are considered venous because the blood vessels that join the two capillary beds are either veins or venules. Examples of such systems include the hepatic portal system and the hypophyseal portal system. Unqualified, "portal venous system" often refers to the hepatic portal system. For this reason, "portal vein" most commonly refers to the hepatic portal vein. |
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Peristalsis
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Peristalsis is the rhythmic contraction of smooth muscles to propel contents through the digestive tract. The word is derived from New Latin and comes from the Greek peristaltikos, peristaltic, from peristellein, "to wrap around," and stellein, "to place."
In much of the gastrointestinal tract, smooth muscles contract in sequence to produce a peristaltic wave which forces a ball of food (called a bolus while in the esophagus and gastrointestinal tract and chyme in the stomach) along the gastrointestinal tract. Peristaltic movement is initiated by circular smooth muscles contracting behind the chewed material to prevent it from moving back into the mouth, followed by a contraction of longitudinal smooth muscles which pushes the digested food forward. |
