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17 Cards in this Set
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- Back
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PHYSIO EXAM 4: RENAL 3
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PHYSIO EXAM 4: RENAL 3
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Clearance
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C = UV/P
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Clearance = GFR when?
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When the filtered substrate is neither reabsorbed nor secreted.
Ex: inulin |
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Creatinine
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Filtered and not reabsorbed.
Creatinine clearance gives a good approx of GFR. A physiological waste product produced at a steady state. Does NOT need to be injected like inulin. |
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How else can clearance be estimated?
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From plasma creatinine levels
NOTE: if clearance is higher, then there is lower creatinine conc. remaining in the plasma. |
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PAH
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Para-amino-hippurate
Gets secreted AND filtered, therefore, is much larger than GFR. |
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What does PAH measure?
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Renal plasma flow
Can detect obstruction of renal blood flow. |
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Maximal urine osmolarity
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1200-1400 mosmol/L
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Reanl countercurrent multiplier
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1. involves loop of henle
2. loop forms countercurrent arrangement 3.crucial differences btw descending limb and thick ascending limb (TAL). |
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What takes place at the TAL?
Descending limb? |
NaCl reabsorption
Descending limb: water permeability. |
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Descending limb vs. ascending limb:
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Descending limb: water leaves tubule
Ascending limb: solute leaves tubule. |
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Where is the diluting segment?
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End of the ascending limb and right before the distal tubule.
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Collecting duct
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Site of water reabsorption
Possible due to the establishment of high medullary osmolarity. |
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Urea
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Can contributes up to 50% to total inner medullary osmolarity.
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What is the purpose of the countercurrent multiplier mechanism?
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To concentrate the urine and to conserve water.
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Where does the energy come from for the establishment of the medullary osmotic gradient?
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From hydroysis by the basolateral Na pump in the TAL.
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The corticomedullary osmotic gradient is possible because?
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The asymmetric distribution of H2O and NaCl transport in the descending vs. ascending limb.
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