BIO 3200 Human Physiology The Kidneys Lecture 17

Chapter 19 BIO 3200 Human Physiology The Kidneys Lecture 17 rt 1: Blood Flow Through the Kidne Gas Exchange & Transport O2 is carried in blood bound to hemoglobin in red blood cells O2 binding to Hb is cooperative; S shaped binding curve Hb binds O2 more tightly at high pH Hb binds O2 less tightly when CO2 is high Fetal Hb binds O2 more tightly than adult Hb, so the embryo can take O2 from the mother’s blood Carbon dioxide is carried in blood mostly as HCO3- CO2 diffuses into red blood cells and is converted to HCO3- by carbonic anhydrase HCO3- leaves the red blood cells by exchanging with Cl- Breathing is controlled by respiratory neurons in the medulla Blood Flow Through the Kidneys Kidneys receive 20% of cardiac output (1.0 L/min) This is 600 mL/min of plasma (Recall that about 60% of the blood is plasma) Glomerular Filtration In the kidneys, plasma is filtered into the nephrons Water, salts, nutrients and other desirable material is taken back About 99% of water is reabsorbed Glomerular Filtration About 20% of plasma is filtered (125 mL/min) This is the normal glomerular filtration rate The kidneys filter about 4% of the blood every minute Chro