Renal Phys ML: 7 Flashcards
What are the two ways to alter Na+ excretion to maintain homeostasis
- regulating the filtered load by changing GFR (less common)
– only occurs when there is a large MAP change
-regulating the rate of reabsorption ( more common)
– occurs when there is a large map change and differences with ingestion
What happens when plasma volume drops
a decrease in GFR reduces Na+ and H2o loss
What happens when you have a gain of H20 and Ma+ what goes the boy due to lower map?
less sympathic activity, so AA will dilate and increase in GC pressure and increase in GFR so you can excrete the excess Na+ and H20
what does RAAS do?
control sodium reabsorption by secreting renin
What are the three stimuli that will cause renin secretion
-increase activity of renal sympathic nerves
- decrease in arterial pressure
-decrease in GFR which will cause low flow to macula densa
What does renin do when plasma volume decreases
it will increase to save Na+ and H2O to increase MAP
What enzyme converts angiotensin 1 to active form
ACE enzyme
Where does aldosterone mediated Na+ reabsorption occur?
in the cortical collecting duct
What do ACE inhibitors do?
block conversion of angio 1 to 2
What do Ang 2 blockers do?
block angiotensin 2 from binding to receptor
- stops acute vasoconstriction and long term sodium and water retention
What do aldosterone receptor blockers do
stop long term h20 and na+ retention by blocker aldosterone
What is ANP
Atrial natriuretic peptide
- it is anti aldosterone, it increases the loss of Na+ via urine
What secretes ANP
atrial cells
When is ANP secreted?
when you have more MAP (plasma volume increases)
What does ANP do to lower plasma volume?
-acutely alters arterioles to increase GFR
– afferent dilation and efferent constriction
-long term decreases Na+ reabsorption
– lower reabsorption load
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