Final Lecture: Renal Final Flashcards
___% of solutes that get filtered get reabsorbed at the TAL
25%
the “di” in “di“uresis refers to:
- electrolytes
- water
with diuretic therapy, the main volume source of urinary excretion comes from:
ECF
of the ECF, how much volume is plasma and how much is ISF?
1/5 plasma
4/5 ISF
if a pt was given a diuretic and “shaved off” 1L of ECF, how much of it would be plasma?
200 ml would be plasma and excreted; the plasma is fluid from the cardiovascular system and this is sufficient enough to drop BP
what is meant by diuretic therapy maintaining fluid balance?
continued dosing of diuretics does not continue to deplete fluid volume of the patient; it maintains balance from the initial diuretic exposure
explain how the body responds to extra sodium intake in a normal, healthy person with a MAP of 100 mmHg:
extra Na+ intake means less Na+ reabsorption
this is accomplished with AT II regulation
extra salt > suppressed AT II > decreased Na+ reabsorption > may stimulate thirst for increased water intake for balance
describe how the body responds to an increase/decrease in Na+ intake with chronic AT II blockade:
- low AT II means there will be an inability to retain Na+ to keep BP normal
- low AT II > low Na+ reabsorption (slows down Na+/K+/ATPase pump which slows down NHE) > coupled with a low MAP will make it harder to have a normal BP
- if the Na+ intake is high, BP will increase since AT II is ALREADY preventing the EA from constricting (which means it’s already dilated, so it cannot further reduce MAP)
describe how the body responds to an increase/decrease in Na+ intake with chronically high levels of AT II:
- MAP increases with increases in Na+ intake (more AT II = faster Na+/K+/ATPase pump spinning = more NHE pump spinning = increased MAP)
- this is due to the fact AT II is incapable of being suppressed
- also more AT II means chronically constricted EA, which means higher MAP)
in a patient with L renal artery stenosis with an initial MAP of 100, what would the R kidney do to ameliorate BP changes?
- the L kidney would have a lower GCP > low GFR > low NaCl count at MD; therefore, it would increase RENIN > increase AT II which would increase AA resistance > increase GFR > increase NaCl reabsorption > increasing MAP
- the AT II affects BOTH kidneys (also causing a higher BP in the R kidney)
- the R kidney would notice this change and will try to REDUCE renin
- the net affect would be a high increase in MAP and the R kidney will try to balance the L kidney’s affects, but won’t be able to fully compensate because the R kidney can only constrict its AA so much to prevent overperfusion
what is salt-sensitive HTN?
- most prevalent in african-americans and asians
- a “decreased renin” form of HTN
- also found in those who have stenotic renal arteries
how do taste receptors work?
- NaCl (or whatever flavor) binds to a receptor on a tastebud to stimulate depolarization to increase AP activity
- if Na+ were introduced (as in table salt), Na+ will depolarize the tastebud (Cl- will not since there are no Cl- receptors on tastebuds)
- K+ can also depolarize tastebuds
delineate how extra Na+ intake would affect the kidney and BP
- increased Na+ intake means more H2O intake
**2. increased blood [Na+] ** * - increased [Na+] in glomerular filtrate
- Increased # of Na+ counted at MD
- repressed renin release
- decreased AT II levels
- decreased ALDO
8. diuresis to get rid of extra salt
- increased blood volume
- increased MAP
- increased GCP
- increased GFR
- increased # of Na+ at MD
- decreased AT II
- decreased aldo
- increased diuresis
* gets rid of extra salt
if someone were to have a unilateral nephrectomy, explain how the remaining kidney would function in terms of creatinine clearance:
- 2 million nephrons total (1 million per kidney)
- if filtration rate is now cut in half (62.5 ml/min from 125 ml/min), and creatinine production remains the same (1 mg/dL), then the remaining kidney will have to compact the same amount of creatinine into less volume to be filtered
- since creatinine production is no longer equal to creatinine excretion, balance will need to be restored by increasing serum [creat.] from 1mg/dL to 2mg/dL
similar to COPD patients getting rid of excess CO2 (d/t poor lung compl)
