13. BIOS 281 Electrolyte Balance Urinary 3.0

Early distal tubule transport of ions based on

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Unformatted text preview: ot permeable to water, permeable to some ions (Na and Cl) •  Thick ascending loop of Henle is hypoosmo=c •  Na, K, Cl, ions are reabsorbed by secondary ac=ve transport •  Concentra=on gradient drives reabsorp=on of Mg, Ca •  Buffering •  Aldosterone promotes Na and Cl reabsorp=on in the ascending limb –  What does this do to urine? •  Early distal tubule: transport of ions based on physiological state •  Late distal tubule: buffering based on hormones, water reten=on based on hormones •  Medullary collec=ng duct: further concentra=on of urine in most cases (depending on physiological state and hormones) Be able to label this very thoroughly! Vasopressin/ADH •  Regulates body reten=on of water: released when body is dehydrated (high osmo=c pressure) •  In kidney, leads to increased urine osmolarity (concentra=on) and decreased water loss by: –  Increasing water permeability at distal tubule and collec=ng duct •  Inser=on of water channels (aquaporin- 2) –  Increasing permeability of inner medullary por=on of collec=ng duct to urea by regula=ng the cell surface expression of urea transporters •  Facil...
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