Glomerular Filtration and Renal Blood Flow Flashcards
What cells secrete renin?
Granular cells
Approximate size cut-off for glomerular filtration?
~60,000 daltons
T/F the fenestration in the epithelium contributes to filtration.
F. The gaps are too large, so they’re pretty fucking useless.
What two components mainly contribute to the filtration?
Podocytes and the basal lamina
What is the main force driving plasma INTO the tubule?
Pressure within the glomerular capillary (Pgc)
What are the forces driving plasma OUT of the tubule?
Tubular backpressure (Pt) and the osmotic force (πgc)
How does the colloid osmotic pressure arise?
As water is filtered and large proteins are left behind, the concentration grows within the capillary
Is the net filtration pressure small or large?
Small. Like 6mmHg
T/F: The kidneys work to keep GFR constant, even in a huge excess of water intake.
T. Otherwise we’d nonspecifically filter everything else too, then waste energy reabsorbing it
What step does the kidney change to accommodate an intake excess?
Reabsorption
T/F: Changes in MAP case corresponding and proportional changes in glomerular capillary pressure.
F. The tubules would be overwhelmed and it’d all be fucked.
Renal response to severe hypovolemia?
Coordinating constriction of afferent AND efferent capillaries to maintain GFR with a decreased blood flow.
What 2 baroreceptors stimulate a renin release?
- External baroreceptors
2. Intrarenal baroreceptors
What is the role of renal prostaglandins?
In response to AGII, they selectively vasodilate the afferent renal capillaries to maintain some GFR, and reduce the risk of renal ischemia.
T/F: Renal prostaglandins totally eliminate the hypovolemic response.
F. That’d be stupid. They just blunt is so the kidneys are still perfused and don’t die.
