Editing Renal blood flow, glomerular filtration
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*So, it makes sense that giving NSAIDs to a pt who is volume depleted (or otherwise has poor kidney function) is bad because it will reduce prostaglandin synthesis, therefore reduce the amount of vasodilation force on the afferent arteriole, and result in lower RBF, lower GFR, and less filtration. | *So, it makes sense that giving NSAIDs to a pt who is volume depleted (or otherwise has poor kidney function) is bad because it will reduce prostaglandin synthesis, therefore reduce the amount of vasodilation force on the afferent arteriole, and result in lower RBF, lower GFR, and less filtration. | ||
*So, '''think of prostaglandins of the brake that slows vasoconstriction'''. | *So, '''think of prostaglandins of the brake that slows vasoconstriction'''. | ||
- | + | Where do the prostaglandins come from? Is there a local, renal source? | |
===Hallmark of glomerular disease=== | ===Hallmark of glomerular disease=== | ||
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**Blood colloid pressure (Pi<sub>GC</sub>) wants to keep stuff in the blood. | **Blood colloid pressure (Pi<sub>GC</sub>) wants to keep stuff in the blood. | ||
***Note that the blood colloid pressure (P<sub>GC</sub>) increases proximal to distal in the capillary as water is filtered out. | ***Note that the blood colloid pressure (P<sub>GC</sub>) increases proximal to distal in the capillary as water is filtered out. | ||
- | **Filtrate colloid pressure (P<sub>FC</sub>) wants to keep stuff in the interstitial fluid | + | **Filtrate colloid pressure (P<sub>FC</sub>) wants to keep stuff in the interstitial fluid. |
**Capillary hydrostatic pressure (P<sub>GC</sub>) wants to force stuff out of the capillary. | **Capillary hydrostatic pressure (P<sub>GC</sub>) wants to force stuff out of the capillary. | ||
- | **Filtrate hydrostatic pressure (P<sub>BS</sub> | + | **Filtrate hydrostatic pressure (P<sub>BS</sub>wants to force fluid into the blood. |
***P<sub>BS</sub> is negligible. | ***P<sub>BS</sub> is negligible. | ||
*There is a constant called the '''glomerular ultrafiltration coefficient (K<sub>f</sub>) that accounts for the normal surface area and capillary permeability. | *There is a constant called the '''glomerular ultrafiltration coefficient (K<sub>f</sub>) that accounts for the normal surface area and capillary permeability. | ||
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*Recall that GFR = K<sub>f</sub> * (P<sub>GC</sub> - P<sub>BS</sub> - Pi<sub>GC</sub>) | *Recall that GFR = K<sub>f</sub> * (P<sub>GC</sub> - P<sub>BS</sub> - Pi<sub>GC</sub>) | ||
*So when Pi<sub>GC</sub> (blood colloid osmotic pressure) decreases, GFR goes up. | *So when Pi<sub>GC</sub> (blood colloid osmotic pressure) decreases, GFR goes up. | ||
- | + | Does giving saline and therefore increasing GFR decrease the effective dose of a medicine because of faster clearance? | |
- | + | ||
===Relationship of glomerular blood flow and GFR=== | ===Relationship of glomerular blood flow and GFR=== |