renal 2 Flashcards
Describe the myogenic mechanism of autoregulation
- Controls Renal blood flow and Glomerular filtration rate
- when the tension on the walls of vessels increase –> contraction of smooth muscle to raise vascular resistance –> prevents excessive RBF and GFR
What is the usual relationship in the regulation of GFR and RBF
- they are regulated in parallel as arterial pressure increases (consistency); GFR is even more heavily controlled
what substance is not very well controlled with an increase in arterial pressure
URINE OUTPUT
Describe the method of TUBULOGLOMERULAR feedback for autoregulation during increasing arterial pressure
- If you increase renal arterial pressure –> increase GFR and RBF, so need to feedback to decrease them
- Solution = CONSTRICT the AFFERENT arterioles
Describe autoregulation for increased renal arterial pressure (2 overall effects)
- Increase renal Arterial pressure, increase GFR and RBF –> less time to reabsorb water, get large volume at loop of henle –> also less NaCl removed so more reaches macula densa –> increased intake of NaCl to macula densa –> increase release of ATP and adenosine to smooth muscle –> increased intracellular Ca2+ –> increase vasoconstriction of AFFERENT ARTERIOLE (vasodilation would increase the GFR and RBF)
What do the ATP and adenosine also do in the kidney
inhibit release of renin
What about a tubuloglomerular feedback mechanism for DECREASED renal arterial BP
renal BP falls –> GFR decreases –> NaCl in tubule FALLS –> UPTAKE NaCl from macula densa –> decreases adensoine and ATP –> VASODILATE the afferent arteriole –> GFR increased and release of renin (so more angiotension II to constrict the efferent to further assist)
How do we maintain Na concentration
Make a gradient with the Na/K ATPase so sodium can always flow down conc gradient into blood from the tubular fluid
what are the 4 overal reasons for autoregulation
1) many activities change BP, but don’t necessarily want to tie these to GFR or RBF
2) BP changes suddenly, but don’t want interference with urine
3) hypertension could damage glomerulus
4) NE is released with symp nervous stimulation which interferes with autoreg. (afferents constrict and GFR lessens but we want opposite for instance)
What are the relationships of hypertension to renal disease
- cyclic; Hypertension causes renal damage, but any renal damage also causes more hypertension
describe the vasodilator prostaglandins
- PGE2 and PGI2 (prostacyclin)
- prostacyclins are vasodilators to oppose things like NE; become unapposed vasoconstriction and renal damage when PGE2 and PGI2 are reduced.
What are the effects of NSAIDS on the prostacyclins/prostaglandins
NSAIDS inhibit prostoglandin synthesis and cause ISCHEMIC RENAL DAMAGE (b/c of unhibited vasoconstriction)
define chronic renal disease
- if # of nephrons goes down, each nephron just works harder to maintain GFR; do this by increasing PGE2 and PGI2 –> dilate afferent arterioles and increase single nephron GFR
What if the patient who is compensating for chronic renal disease takes NSAIDS
- no more prostaglandins, can get immediate renal failure
which blood flow in kidney is especially dependent on prostaglandins
medullary