BIOL 152 1st Edition Lecture 24 Outline of Last Lecture Osmoregulation Outline of Current Lecture Osmoregulation Current Lecture Osmoregulation Mammalian Kidney Renal arteries and veins Ureter bladder urethra Renal cortex medulla Nephrons o Cortical 80 o Juxtamedullary loop of Henley concentration gradient and goes all the way down o Glomerulus o Bowman s capsule Pathway through Kidney 1 Proximal tubule 2 Loop of Henle 3 Distal tubule 4 Collecting duct 5 Renal pelvis 6 Ureter The blood vessels of a nephron Afferent arterioles Efferent arterioles Peritubular capillaries These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Vasa recta The vessels and nephron tubules are bathed with interstitial fluid Proximal Tubule Non selective entry from Bowman s capsule The fluid contains water waste products and valuable nutrients Reabsorption of NaCl and H2O Maintain pH of filtrate H NH3 and HCO3 Loop of Henle Descending portion o Permeable to water not solutes o Reabsorption of water due to increased osmolarity of interstitial fluids hyperosmotic Ascending portion o Permeable to solutes not water o Thin section NaCl out passively o Thick section NaCl out actively Distal Tubule Maintain pH of filtrate H and HCO3 Reabsorption of NaCl Secretion of K into filtrate Collecting Duct Carries filtrate to renal pelvis Active reabsorption of NaCl hormonally controlled Filtrate becomes increasingly concentrated as it loses H 2O to hyperosmotic medulla Ability to Conserve Water Blood 300 mosm L urine 1200 mosm L Create and take advantage of solute gradients Location of loop of Henle and collecting duct Active transport in loop of Henle requires E o To produce a region of high osmolarity that can be used to extract water from the filtrate in the collecting duct o Any osmotic gradient will dissipate if not maintained Regulation of Kidney The amount of Na Cl and water reabsorbed in the distal tubule and collecting duct varies with the animal s condition and is under hormonal control o Antidiuretic hormone ADH responds to high blood osmolarity dehydration o Renin angiotensin aldosterone system RAAS responds to decreased blood volume pressure without a change in osmolarity diarrhea loss of blood Antidiuretic hormone ADH o Osmoreceptor in hypothalamus measures osmolarity of blood Set point 300 mosm L o Increases H2O reabsorption by kidney in distal tubule and collecting duct o Result is more hyperosmotic urine o Negative feedback RAAS JGA Juxtaglomerular apparatus Renin angiotensin aldosterone system Complex feedback circuit that regulates blood volume pressure
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