SC BIOL 460 - Water and Salt Reabsorption (3 pages)

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Water and Salt Reabsorption

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Water and Salt Reabsorption


Regulation of filtrate and water and salt re absorption

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University Of South Carolina-Columbia
Biol 460 - General Physiology
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BIOL 460 1st Edition Lecture 31Outline of Last Lecture I. Acid-base Balance continuedII. Urinary Systema. Kidney i. NephronIII. Glomerular FiltrationOutline of Current Lecture I. Regulation of Glomerular FiltrateII. Reabsorption of Na and WaterIII. Loop of HenleIV. ADHV. Aldosterone VI. Renal acid-base balance Current LectureRegulation of Glomerular Filtrate1. Exteriora. Done by sympathetic division of ANSi. Causes vasoconstriction of afferent arterioles b. If there is blood less→ fight-or-flight→ conserve blood volume and keep blood pressure high as possible2. Intrinsica. Renal auto regulation b. Macula densai. Detects absorption increase of GFR by detecting increase in number of Naions in the filtrateii. Secretes adenosine1. Activates afferent arteriole iii. Also inhibit granular cells of SGA from secreting reninThese 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.Reabsorption of Na and H2O from Filtrate1. 180 L of ultrafiltrate produced2. 2L of urine3. Salt reabsorption by active transport4. Water needs a concentration gradient a. Osmosis 5. Proximal convoluted tubule reabsorbs 2/3 of water and salt in filtratea. Basal surface of PCTi. Na+/K+ pump1. Na+ out, K+ in b. Hypertonic → water follows salti. Diffuse into cytoplasm then tissue spaces and back into bloodc. CO2 transport can also occuri. Glucoseii. Can also pump protons into filtrate via antiportd. Remaining 15% is hormonally controlledi. Presence or absence of ADH and aldosteroneLoop of Henle1. Create osmotic gradienta. Pump salt from filtrate into medulla where it accumulatesb. Concentration gradient draws water in medulla2. Perform countercurrent multiplicationa. Ascending limb is driving forceb. Salt is pumped out into tissue space of medulla by active transport like cells of PCTi. This salt doesn’t go into bloodstream1. PCN→ vasa recta traps slatii. Cell of limb are impermeable to water so filtrate gets diluted3. Vasa recta of PCN- parallel to LHa. Takes water from medulla and returns it to bloodstream but salt gets trapped in medullai. Countercurrent exchangeADH1. Presence- when blood is too saltya. Acts on cells of collecting duct and triggers to insert aquaporins into membrane of collecting duct2. Absence a. Aquaporin kept insideb. Collecting duct impermeable to waterAldosterone1. Presence a. All of salt is reabsorbed2. Absence a. Slat will remain in ultrafiltrateb. Causes reabsorption of salt and excretion of K+ in urineRenal Acid-Base Regulation 1. Kidneys help present pH change by secretion of protons into ultrafiltratea. Urine is slightly acidic (pH 5-7)2. CO2+ H20 → H2CO3→ H+ + HCO33. By way of filtration 4. Via antiport- uphill movement of protons into ultrafiltrate5. Alkalosisa. Increase in pH i. Cells pump fewer protons into ultrafiltrate by

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