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12 Cards in this Set
- Front
- Back
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Why is it important to concentrate your urine?
How much can you conc. it? |
-To conserve body water.
-Conc up to 1200 mOsm, the same as the ISF of inner medulla. |
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Where is ADH action important (in what renal cells)?
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In the collecting duct cells.
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How does ADH work?
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1. It's carried in the blood.
2. Released, binds membrane receptor on coll. duct cell. 3. Activates cAMP-depend. PKA, which causes aquaporin II to insert on lumenal membrane. 4. INCREASED H2O REABSORPTION. |
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what is the min and max concentration that the filtrate can be?
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50 Osm is minumum
1200 Osm is maximum. |
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what is the purpose of countercurrent multiplication?
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to develop a concentrated ISF in the inner medulla, to allow H2o reabsorption from the medullary collecting duct.
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What ions move from which parts of the nephron, in order to develop the high ISF concentration?
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-Water reabsptn from desc limb.
-Na/Cl reabsptn from ascnd limb. -Water NOT reabsbd from asc. lmb |
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What is countercurrent exchange, and what is its purpose?
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-Exchange of H2O/Na/CL from peritubular capillaries. -Prevents washout of concentrated ISF develpd by countercurr. multiplication.
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What are the special peritub. capillaries called?
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Vasa recta, in inner medulla.
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How do H2O/Cl/Na move when flowing through vasa recta by the descending limb?
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H2O moves out, Cl/Na move in, so the blood is 1200 mOsm at the bottom of the loop.
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How do H2O/Cl/Na move when flowing through vasa recta by the ascending limb?
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H2O moves back in, Cl/Na move out, so the blood is once again 300 mOsm (normal) at the top.
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If there was no Vasa recta, what would happen?
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All of the Na/Cl creating the concentrated ISF would move down their gradient into blood vessels, and washout the ISF.
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what is urea's role in concentrating urine?
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As Na/Cl are reabsorbed from asc. limb, urea replaces them. This makes NaCl reabsptn more efficient. Urea is then reabsorbed at collecting duct.
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