BIOL 460 1nd EditionFinal Exam Study Guide Lectures: 24-34Possible Essay Questions:1. Platelet Release ReactionWhen a vessel is damaged there is a rupture in the endothelium and underlying tissue is exposed (lots of collagen). Platelets have proteins that stick to collagen. Von Willibrands Factor (VWF) is a protein that is produced by endothelial cells, which help platelets adhere to collagen. This causes the platelet release reaction. Degranulation occurs and vesicles undergo exocytosis, fusing with the plasma membrane. Thromboxin A2 (prostaglandin) and ADP are released. Thromboxin A2 helps the platelets stick and is a vasoconstrictor, while ADPmakes the platelets sticky. Growth factors are released to speed the repair of connective tissue. Tissue factor is released and is important in clotting.2. Renin-Angiotensin-aldosterone SystemThe kidneys contain juxtaglomerular apparatus that secretes Renin. Low blood volume occurs when the kidneys are not getting enough blood at a high enough pressure to producefiltrate properly. Granular cells of JGA secrete renin into blood. Renin converts angiotensinogen  angiotensin I (plasma protein produced by liver). Angiotensin  [ACE]  Angiotensin II. ACE – angiotensin converting enzyme. AII raises blood pressure and blood volume, negative feedback for renin. The following are functions of Angiotensin II: powerful vasoconstrictor- raising BP, causes adrenal cortex to secrete aldosterone (mineralocorticoid), and stimulates thirst centers.3. Starling’s Forces (in pulmonary circuit, renal corpuscle, systemic capillaries)Starling’s forces are forces that cause filtration. In the pulmonary there is low pressure and low resistance. Pulmonary hypertension would cause pulmonary congestion due to failure of the left ventricle. A heart attack can cause pulmonary edema, which is accumulation of fluid in lungs. Edema is excess accumulation of tissue fluid. 4. Baroreceptor ReflexBaroreceptor reflex regulates short term blood pressure. Occurs when you stand quickly and get dizzy. A slow baroreceptor reflex makes it worse. Baroreceptors are aortic rich in the carotid sinus. They are constantly generating action potentials. The higher the pressure, the more APs generated. They send sensory information to the medulla. This isa vasomotor center and cardiac center. Beta blockers prevent this reflex- syncope (pass out).5. Transport of O2 in the Blood (including hemoglobin dissociation curve)i. Hemoglobin is four polypeptides. Hemo mean heme group (porphorin ring with iron in center) and globin means protein. The iron forms a covalent bond with O2. O2 carrying capacity in blood is determined by hemoglobin. Anemia is when less O2 than normal because of lack of hemoglobin. Polycythemia is more hemoglobin in blood than normal. Kidneys determine how much hemoglobin is in the blood. They secrete erythropoietin and the bone marrow will produce more RBCs. The oxyhemoglobin dissociation curve is S shaped, flat at high and low ppO2, and drops slightly during exercise. 6. Transport of CO2 in the Bloodii. 10% of CO2 is dissolved in plasma, 20% bonds to globin of hemoglobin producing carbaminohemoglobin, and the other 70% is transported as bicarbonate. RBCs contain carbonic anhydrase, which accelerates reaction, CO2 + H2O  H2CO3  H+ + HCO3-. The reaction can accelerate in either direction. Protons combine with globin part of hemoglobin, enhancing the Bohr Effect. HCO3- exits RBC as Cl- enters. This is the chloride shift. Everything is reversed exactly when CO2 reaches lungs.7. S and F of the PCT (how it absorbs 65% of the water and salt in filtrate)The proximal convoluted tubule is part of the nephron, which is the functional unit of the kidney. It leads from Bowman’s capsule to the loop of Henle. 180 liters of ultrafiltrateis produced. 2liters of urine is produced. Salt is reabsorbed by active transport but waterneed a concentration gradient so it is reabsorb through osmosis. The basal surface of PCT contains a Na+/K+ pump, which pumps Na+ out and K+ into cells. Hypertonic → water follows salt. The K+ diffuses into cytoplasm and then into tissue spaces and back into the blood. CO2 transport also occurs via antiport and can pump protons into filtrate.The other 15% is controlled by hormones ADH and aldosterone. 8. Hormonal control of water balance (i.e. S and F of the LH, countercurrent multiplication, countercurrent exchange, vasa recta, collecting duct, aquaporins, ADH)The loop of Henle creates osmotic gradient. It pumps salt from filtrate in medulla and accumulates there. The concentration gradient draws water in medulla. LH performs countercurrent multiplication. The ascending limb is the driving force. Salt is pumped out into the tissue spaces of medulla by active transport, just like the cells of PCT. This salt doesn’t go into bloodstream because of PCN and the vas recta causes salt to be trapped. Cells of limb are impermeable to water so filtrate gets diluted. The vasa recta ofPCN takes water from medulla and returns it to the bloodstream but salt is trapped in the medulla still. This is the countercurrent exchange. ADH acts on cells of collecting duct and trigger them to insert aquaporins into membrane of cell duct. In the absence ofADH, aquaporins are kept inside and the collecting duct is impermeable to water. 9. Renal acid/base RegulationThe kidneys help present pH change by secretion of protons into ultrafiltrate. It does theone by way of filtration. Another way is via antiport, which is uphill movement ofprotons into ultrafiltrate. Alkalosis is an increase in pH and the PCT pumps fewer protonsinto the ultrafiltrate by