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## Questions and Answers ### Equation Write out the equation relating pressure gradient, resistance, and flow. * Flow = Pressure Gradient/Resistance ### Hematocrit Define hematocrit. Describe the importance of the hormone erythropoietin to hematocrit. * Hematocrit: % of formed elements in bloo...

## Questions and Answers ### Equation Write out the equation relating pressure gradient, resistance, and flow. * Flow = Pressure Gradient/Resistance ### Hematocrit Define hematocrit. Describe the importance of the hormone erythropoietin to hematocrit. * Hematocrit: % of formed elements in blood (almost exclusively erythrocytes) * Erythropoietin increases erythrocyte number, increasing hematocrit. An increase in the number of erythrocytes would increase the ability of the blood to deliver oxygen (the primary function of erythrocytes). An increase in hematocrit would increase resistance to blood flow. ### Blood Components List the 2 components of blood (the "liquid" portion and the "solids" portion). * Liquid portion - Plasma * Solids portion Describe the relative amount of each of these 2 components. What is the major component of the liquid portion of blood? List the 3 major components of the solid portion of blood. For these 3, give a function and the relative amount of each. * Liquid portion = Plasma. Approximately more than half of whole blood. Plasma is almost exclusively water. * Solid portion of blood: (1.) Erythrocytes: transport of oxygen; almost 100% of formed elements, (2.) Leukocytes: immunity; less than 1% of formed elements, (3.) Thrombocytes: Blood clotting; less than 1% of formed elements. ### Blood Clotting Components Describe the importance of each of the following: (a.) Plasminogen; (b.) Fibrin; (c.) Vascular spasm; (d.) Thrombin; (e.) Embolus. * (a.) Plasminogen: Inactive form of blood protein; when activated to plasmin, a blood protein that dissolved blood clots. * (b.) Fibrin: Active form of blood clotting protein; final step in clotting process - forms clot. * (c.) Vascular spasm: Smooth muscle contraction in response to damage to a blood vessel; decreases blood flow to injury. * (d.) Thrombin: Active form of blood clotting protein; converts fibrinogen (inactive protein) to fibrin. * (e.) Embolus: A piece of a blood clot that moves in the blood; will lodge in a blood vessel, decreasing blood flow downstream. ### Heart Structures Describe the importance of each of the following (a.) Atrium; (b.) AV node; (c.) Artery; (d.) Vein; (e.) Ventricle. * (a.) Atrium: Input chamber of the heart; receives blood from veins. * (b.) AV Node: Pacemaker that causes ventricular depolarization (activation); represented by the QRS complex of the EKG. * (c.) Artery: Blood vessel carrying blood away from the heart; receives blood exiting a ventricle. * (d.) Vein: Blood vessel carrying blood towards the heart; carries blood to an atrium of the heart. * (e.) Ventricle: Output chamber of the heart; pumps blood out into an artery ### Compliance Define compliance. Describe the relationship between the thickness of a blood vessel's walls and compliance. Describe the relative thickness of systemic arteries and pulmonary arteries. * Compliance: Stretchiness or elasticity of a blood vessel. Compliance is inversely proportional to the thickness of a blood vessel. Systematic arteries have thicker walks (since systemic circulation has higher pressure) than pulmonary arteries. * Baroreceptors respond to stretch of arterial walls, causing a drop in blood pressure. Moving baroreceptors to pulmonary arteries would increase their activity (since pulmonary arteries would stretch more easily), causing blood pressure to drop. ### Antigen, Pathogen, MHC Define antigen. Define pathogen. List the 3 antigen-presenting cells. Define MHC. List the 2 types of MHC and where each is located. * Antigen: Any molecule (most often a protein) is not recognized by the immune system. * Pathogen: Any disease-causing microorganism. * Antigen-presenting cells: (1.) Macrophages, (2.) Dendritic cells, (3.) B lymphocytes. * MHC: Major histocompatibility complex = a group of membrane proteins used by the immune system for identification. * MHC I: Found on the membranes of alls cells with nuclei. * MHC II: Found only on antigen-presenting cells. ### Inflammation List the 4 cardinal signs of inflammation. Describe reasons for each of the 4 signs. * Redness — due to increased blood flow (to deliver more immune cells to the site of injury). * Increased temperature - due to increased blood flow and increased metabolism. * Swelling - due to increased permeability of blood vessels (to allow immune cells to exit blood and move to the site of injury). * Pain - due to the release of pain-inducing chemicals. ### Antibodies List the 5 classes of antibodies (immunoglobulins). Give a function for each. * Immunoglobulin A (IgA): Found in many body secretions * Immunoglobulin D (IgD): B cell receptor * Immunoglobulin E (IgE): Allergic reactions * Immunoglobulin G (IgG): Most common antibody; crosses placenta * Immunoglobulin M (IgM): Released in high amounts after second exposure to an antigen. ### T Lymphocytes List the 4 types of T lymphocytes (T cells). Give a function for each. Define active and passive immunity. Which of the 4 types of T cells is most important in active immunity? Explain * Helper T: "ON" switch to active immunity * Suppressor T: "OFF" switch to active immunity * Cytotoxic T: Destroy virus-infected cells * Memory T: When the same antigen is encountered, divide rapidly to produce all types of T cells. * Active immunity - formation of memory cells, which will allow for a stronger response if the same antigen is encountered. * Passive immunity - no formation of memory cells, inhibiting a stronger response if the same antigen is encountered.