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Renal Phys 2 and 3
WVSOM -- Renal Physiology -- Lectures 2 and 3
| Question | Answer |
|---|---|
| How do you calculate the amount of a substance secreted in urine? | amount filtered – amount reabsorbed + amount secreted |
| What are the 3 layers of the filtration membrane? | capillary endothelium of glemerular capillaries, glomerular basement membrane and layer of epithelial podocytes |
| What factors effect the physical solute characteristics on filtration? | Molecular size, electrical charge and shape |
| What if a solute is protein bound? | it can’t get thru |
| How does molecular size affect filtration? | low molecular weight and small effective radius make it easier for it to get thru |
| How does electrical charge affect filtration? | Postive charge are filtered to a great extent (a positive attitude is a good thing to havce…!!!! ) |
| What negative charge molecules go thru despite the negative charge? | chloride and bicarb |
| How does shape affect filtration? | rigid and globular solutes have low filterability, deformable molecules of the same size will go thru much easier! |
| What determines GFR? | rate and net filtration pressure (NFP) |
| What is the equation for net filtration pressure? | Pgc + ∏bc - Pbc - ∏gc |
| What is the equation for Rate of filtration? | Kf X NFP |
| Calculate NFP when Pgc = 50, ∏gc=25, Pbc=10? | 15 L/min |
| How does hydraulic pressure in the capillary change along the length and why? | very little because there is lots of cross-sectinal ara and small resistance to flow |
| How does osmotic pressure change along the capillary? | increases because as more fluid is filtered out of the capillary it leaves proteins behind. |
| What causes an increase in Kf? | glomular surface area |
| What happens to GFR with an increase in Kf? | increased GFR |
| What happens to GFR with increased Pgc? | increase in GFR |
| What causes an increase in Pgc? | renal arterial pressure, afferent arteriolar dilation and efferent constriction. |
| What does an increase in the osmotic pressure of the glomular capillaries result in? | decreased GFR |
| What happens to RBF if afferent arteriolar resistance is increased? | decrease in RBF and decrease in Pgc |
| What happens when there is in increase in efferent arteriolar resistance? | increase in Pgc and decrease in RBF |
| What happens if there is an increase in afferent resistance and an increase in efferent resistance? | Pgc stays the same but there is a decrease in RBF |
| What is RBF? | renal blood flow |
| What is the equation for flow? | change in pressure divided by resistance |
| If RBF goes up what happens to GFR? | GFR increases |
| If RBF goes down what happens to GFR? | GFR decreases |
| What is the equation for filtration fraction? | GFR/RPF |
| Why is Filtration fraction greater at low flows than at higher flows? | because GFR saturates at high plasma flows. |
| What will cause changes in GFR independent of effects on Pgc? | arteriolar resistance |
| What will constriction of only the afferent arteriole do to GFR? | decrease |
| What happens to GFR with only constriction of the efferent arteriole? | GFR increases because rising capillary pressure dominates |
| What does SNS and angiotensin II stimulation do to afferent and efferent resistances? | resistances increase and RBF decreases |
| What does Ang II have more effect on… efferent or afferent? | efferent |
| Where do peritublar capillaries come emerge from? | efferent arteriole |
| What surrounds tubules? | peritubular capillaries |
| How do starling forces affect peritubluar capillaries? | blood in the PCs have a high oncotic pressure due to proteins not being filtered yet has a low hydrostatic pressure do to the resistance of the efferent arteriole. This will FAVOR reabsorption |
| What happens with volume expansion? | afferents and efferents vasodilate, there is a decrease in SNS and RAAS and the FF goes down because RBF is up drastically and more blood enters the peritubular capillaries. |
| What are the two process of autoregulation? | mygenic response and tubuloglomerular feedback |
| What does autoregulation do? | keeps RBF and GFR from varying too widely. The macula densa will release paracrines which will bring things back into equilibrium. |
| What is the RAAS system? | Ang II constricts afferent and efferent artioles (mostly efferent) |
| What does SNS stimulation do? | constricts both afferent and efferent arterioles |
| How does ADH affect the peritubular capillaries? | vasoconstricts but normally total RBF and GFR remain constant |
| What does ANP do to arteriols? | vasodilates the afferent and efferent arterioles causing an increase in RBF and GRF. Will also inhibit secretion of rennin |
| What does Dopamine do to arterioles? | cause vasodilation |
| What do prostaglandinds do to the kidneys? | protects agains excessive vasoconstriction. Help maintain RBF and GFR whenthere is high sympathetic outflow and lots of RAAS |
| Your patient has a primary glerular disease that decreases the surface area available for filtration. What effect will this have on GFR and what will be the autoregularotyr response to it? | GFR will decrease. Paracrines will then be released from the macula densa due to a decreased NaCl that will vasodilate the arterioles causes in an increased GFR, Pgc and RBF |
| You give a person a drug that constricts the afferent arteriole and dilates the efferent arteriole by the same amounts. What effect will this have on GFR, RBF and FF? | Decrease in GF, Increase in RBF and then that will result in a decrease in FF |
| Your patient has entered the ER after a motorcycle accident. His BP is very low and he is tachycardic. You believe he has lost a great deal of blood volume. What is the reflex response to hypotension in respect to RAAS and what will happen to FF? | RAAS will increase because ang II is a vasoconstrictor to compenstate for the hypovolemia. FF will go up because AngII works better on efferent than afferent so thre will be a large decrease in RBF but an increase in GFR |
Created by:
tjamrose
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