Term
| What are the ratios of ECF to ICF? |
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Definition
- 25 L Intracellular fluid
- 12 L interstitial ECF
- 3 L Plasma
Total: 25 L |
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Term
| What is the avg intake/output by the body? |
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Definition
2500 mL intake/output
intake is mostly beverages, then foods
Output is mostly urine, then skin/lungs
Must excrete 600 mOsm/day |
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Term
| How does urine and plasma osmolarity change due to increase in water intake? |
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Definition
- When drinking, urine becomes dilute and a low osmolarity (~100) and urine flow rate goes up. Plasma osmolarity barely changes and solute DOES NOT CHANGE
- Conversely, when conserving water, osmolarity of urine goes up |
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Term
| What is the concentration gradient at various parts of the nephron? |
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Definition
In the cortex - 300 mOsm to match plasma
Becomes more concentrated down the loop of henle, ending at 1200 mOsm.
More dilute up the TAL - initially responsible for creating the concentration gradient in the medulla DCT - diluting segment, reabsorbs Na without water, reaching 100 mOsm
CD- urine is excreted as dilute or reabsorption of water in the presence of ADH |
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Term
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Definition
Release depends on blood volume and Osmolarity. If blood is > 300 mOsm, ADH released --> reabsorption of Na/water
- V1 on blood vessel -Vasoconstriction and decreased GFR. NE also does this
- V2 on collecting duct - upregulation of aquaporins, reabsorption of Na/water |
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Term
| What happens if water is more concentrated than 1200 mOsm |
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Definition
| 1200 mOsm is the greatest concentration of urine. If seawater is drunk, more than what was ingested must be excreted |
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Term
Where does ADH work?
Where is water permeable without ADH? |
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Definition
ONLY in the collecting duct
Water reabsorption in the proximal tubule and the DTL |
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Term
| What is the countercurrent mechanism and countercurrent exchange? |
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Definition
Creating a hyperosmotic medullary region to create a gradient for reabsorption of water into the vasa recta
To start the gradient, solid is pulled out of the TAL, diluting that segment and increasing the Op in the interstital space, the Op pulls fluid out of the PT. Filtrate continues to flow, and this process repeats
Equilibrium reached in the DCT at 200 mOsm |
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Term
| What is the function of urea in establishing the gradient? |
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Definition
| Reabsorbed with water in the presence of ADH, secreted in the PT. Helps to establish the gradient |
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Term
| How is blood in the vasa recta affected by the countercurrent mechanism? |
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Definition
| As blood slowly moves along the loop of henle, it concentrates and dilutes according to the gradient |
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