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- Nephronso Cortical (80%)o Juxtamedullary – loop of Henley, concentration gradient and goes all the way down o Glomeruluso Bowman’s capsulePathway through Kidney1. Proximal tubule2. Loop of Henle 3. Distal tubule4. Collecting duct5. Renal pelvis6. Ureter The blood vessels of a nephron- Afferent arterioles - Efferent arterioles- Peritubular capillariesThese 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 fluidProximal 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 portiono Permeable to water, not soluteso Reabsorption of water due to increased osmolarity of interstitial fluids (hyperosmotic)- Ascending portiono Permeable to solutes, not watero Thin section – NaCl out passivelyo 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 H2O tohyperosmotic 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 ducto Any osmotic gradient will dissipate if not maintainedRegulation 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 controlo 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 ducto Result is more hyperosmotic urineo Negative feedbackRAAS - JGA – Juxtaglomerular apparatus- Renin-angiotensin-aldosterone system- Complex feedback circuit that regulates blood
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