Term
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Definition
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Term
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Definition
=V-Cosm
Range of clearance can go from -1.5 (concentrated) to 18 L/day (high). |
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Term
| Water permeability in nephron |
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Definition
| Permeable in the proximal tubule and thin descending limb. Thin descending limb is impermeable to solutes. Impermeable once fluid enters ascending limbs unless Vasopressin is present. |
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Term
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Definition
| Distal convoluted tubule, where tubular fluid is most dilute. |
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Term
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Definition
| Solute reabsorption in thick ascending limb, causes medullary hyperosmolarity. Can cause up to a 200 mOsm gradient between the tubule and the interstitum. |
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Term
| Countercurrent multiplier |
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Definition
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Term
| Countercurrent multiplier components |
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Definition
1. Thin descending limb: Water permeable/solute impermeable. Water flows from the tube into the medulla, which causes solute concentration in the medulla to rise.
2. Thin ascending limb: solute permeable/water impermeable. Passive flow of Na from the tube into the medulla.
3. Active Na, K, Cl transport into the medulla. Increased medullary osmolarity allows water reabsorption. |
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Term
| Countercurrent multiplier limitations |
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Definition
| Efficiency dependent on the length of the loop of Henle and maximum solute gradient (200mOsm) |
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Term
| Results of countercurrent multiplier |
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Definition
| Creates a hypertonic medullary interstitum with a hypotonic tubule. |
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Term
| Role of arginine vasopressin |
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Definition
| Stimulates water and solute reabsorption (stimulates Na, K, Cl transporter) in the distal tubules. |
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Term
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Definition
1. Upregulates production of aquaporins in apical membrane of collecting ducts.
2. Upregulates Na, K, Cl transporter in thick ascending limb.
3. Stimulates insertion of UT1 transporters in the medullary collecting ducts. |
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Term
| Hyperosmolarity affects on vasopressin |
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Definition
| Stimulates vasopressin production to reduce osmolarity in the medulla. |
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Term
| Hypoosmolarity affects on vasopressin |
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Definition
| Suppresses vasopressin production. |
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Term
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Definition
Maximum medullary interstitum.
Maximum distal water permeability
Increases water reabsorption and uOsm. |
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Term
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Definition
Less medulla osmolarity
Minimal distal tubule permeability
Minimum H20 reabsorption and uOsm |
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Term
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Definition
| Vasa recta help maintain medullary hyperosmolarity, remove excess H20 from medulla. |
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Term
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Definition
Descending limb:
1. Reabsorption of NaCl and urea
2. Secretion of water
Ascending limb:
1. Secretion of solutes.
2. Reabsorption of water.
Net result: slight reabsorption of NaCl, urea, and water. |
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Term
| Regulation of water balance |
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Definition
Solute reabsorption in loop of Henle
Dietary protein intake (urea)
Medullary blood flow rate
Tubular fluid flow rate
AVP |
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