Term
| This portion(s) of the nephron functions in isoosmotic reabsorption of solute and water. |
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Definition
-Early proximal tubule
-Late proximal tubule |
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Term
| What is the mechanism by which the early proximal tubule is able to isosmotically reabsorb solute and water? |
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Definition
| -Na-glucose, Na-amino acid, Na-phosphate and Na-citrate cotransporters along with Na-H exchangers bring Na into the cell and then water freely follows. |
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Term
| What effects does parathyroid hormone have on the renal system and what is the mechanism for this? |
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Definition
-Increases Calcium reabsorption
-Increases phosphate excretion by inhibiting Na-phosphate cotransport |
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Term
| What hormones act on the early proximal convoluted tubule? What are their effects? |
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Definition
PTH- inhibits Na-phosphate cotransport
Angiotensin II-stimulates Na-H exchange which would increase water retention |
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Term
| What is the major function of the late proximal tubule? |
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Definition
| Isosmotic reabsorption of solute and water |
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Term
| By what mechanism does the later proximal convoluted tubes isosmotically reabsorb water and solute? |
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Definition
| A chloride gradient drives NaCl reabsorption via Cl- formate anioin exhangers, paracellular Cl- diffusion, and also NaH exhanger. The PCT is freely permeable to water so water follows the solute. |
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Term
| What are the major functions of the thick ascending loop of Henle? |
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Definition
-Reabsorption of NaCl without water
-Dilution of tubular fluid
-Single effect of countercurrent multiplication
-Reabsorption of Ca and Mg which is driven by lumen-positive potential |
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Term
| What is the mechanism by which the thick asending limb of the loop of henle is able to reabsorb NaCl? How is the energy for this generated? |
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Definition
| Na-K-2Cl cotransport with the energy derived from the Na gradient. |
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Term
| What hormones act on the Thick ascending limb of the loop of henle? |
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Definition
| ADH stimulates NaK2Cl cotransport which would decrease water excretion. |
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Term
| What is the major function of the early distal tubule? |
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Definition
| Reabsorbes NaCl without water thereby diluting the tubular fluid. |
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Term
| What mechanism allows the early distal tubule to dilute the tubular fluid? |
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Definition
| The early distal tubule is impermeable to water therefor the Na-Cl cotransporter can move solute across the membrane and water is unable to follow. |
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Term
| What effect does PTH have on the early distal tubule? |
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Definition
| PTH stimulates Calcium reabsorption |
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Term
| What are the major functions of principal cells of the late distal tubule and collecting ducts? |
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Definition
-Reabsorption of NaCl
-K+ secretion
-variable water reabsorption |
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Term
| What mechanisms do the principal cells use to reabsorb NaCl and secrete K+ in the late DCT and CDs? |
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Definition
-Na+ channels
-K+ channels
Neither require energy |
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Term
| Other than reabsorbing NaCl and secreting K+ what else are the late DCT and CD responsible for? What is the mechanism for this? |
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Definition
| Variable water reabsorption through water channels when stimulated by ADH. |
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