Term
| Where is the filtered sodium reabsorbed? |
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Definition
| 65% in the proximal tubule, 25% in the loop of Henle, 10% in the distal nephron |
|
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Term
| What is the major route of sodium excretion from the body? |
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Definition
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Term
| What portion of the nephron is salt impermeable? |
|
Definition
| Descending thin limb of loop of Henle |
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Term
| What portion of the nephron is water impermeable? |
|
Definition
| Ascending thick and thin limbs of loop of Henle and distal convoluted tubule |
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Term
| What are the ranges of reabsorption of water in the collecting duct? |
|
Definition
| 5 to >24% depending on hydration status |
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Term
| What ion does chloride compete with for reabsorption in the proximal tubule? |
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Definition
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Term
| How much bicarbonate is reabsorbed by the end of the proximal tubule? How much chloride? |
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Definition
| 80% bicarbonate; 60% chloride |
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Term
| How does the charge of the proximal tubule with respect to the blood change as you go down the proximal tubule? |
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Definition
The first half is negatively charged with respect to the blood (-4 mV) The second half is positively charged (+4 mV)
*This is because chloride is preferentially reabsorbed in the second half of the proximal tubule |
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Term
| Where do we see isoosmotic reabsorption in the nephron? |
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Definition
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Term
| Does sodium help reabsorption of organic nutrients, phosphate, and sulfate by cotransport or countertransport? |
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Definition
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|
Term
| Does sodium help secretion of hydrogen ion by cotransport or countertransport? |
|
Definition
|
|
Term
| Which part of the loop of Henle has active transporters? |
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Definition
|
|
Term
| Which part of the loop of Henle is freely permeable to water but not salts? |
|
Definition
|
|
Term
| Which part of the loop of Henle is freely permeable to salts but not water? |
|
Definition
|
|
Term
| Which part of the nephron is called the diluting segment? |
|
Definition
| The thick ascending limb because it actively pumps salts out via the Na-K-2Cl symporter but it is impermeable to water |
|
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Term
| What is the target for inhibition by loop diuretics like Furosemide? |
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Definition
| NKCC = Na-K-2Cl symporter in the thick ascending limb |
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Term
| How does the osmolarity of the kidney change from the cortex to the deep medulla? |
|
Definition
| It goes from 300 to 1200 mosm/l |
|
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Term
| What ions and molecules make us the 1200 mosm/l osmolarity of the deep medulla? |
|
Definition
| 25% Cl-, 25% Na+, 50% urea |
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|
Term
| Why is urea an ineffective osmole? |
|
Definition
| It follows water, not leads water |
|
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Term
|
Definition
It causes the insertion of aquaporin water channels into the APICAL membrane of the collecting duct, increasing the water permeability.
*basolateral membrane is always freely permeable to water |
|
|
Term
| What portion of the nephron contains NCCs (Na-Cl symporter) and ENaCs (apical sodium channels)? |
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Definition
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|
Term
| What is the major type of cell in the cortical collecting duct? |
|
Definition
|
|
Term
|
Definition
| Solely on the cortical and medullary collecting duct – not on the proximal nephron |
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