hormonal control of blood pressure Flashcards
what structures make up the juxtaglomerular apparatus?
afferent arteriole, efferent arteriole and distal tubule
where are macula densa cells found?
lining the wall of the distal tubule
what is the function of macula densa cells?
sodium sensors - detecting sodium concentration
if sodium is low, what is GFR?
low
how do macula densa cells act to increase GFR?
act via local hormones to relax smooth muscle of arteriole afferents
also signal to JG cells to increase renin release
where are juxtaglomerular cells found?
around the end of the proximal tubule
what do juxtaglomerular cells do?
release renin into efferent arterioles
explain the renin-angiotensin-aldosterone pathway?
renin cleaves angiotensinogen to AT1
AT1 cleaved by ACE in the lungs to AT2
AT2 passes into arteriole blood and acts on GPCR –> activate phospholipase C and increase systolic Ca2+ conc –> triggers constriction of smooth muscle of systemic arterioles
what is the function of renin?
to raise blood pressure
where is renin released from?
the kidneys
where is ACE released from?
the lungs
how can renin be released?
beta receptors on JG cells when stimulated
sympathetic activation of the nerves innervating the kidneys
how does aldosterone work?
acts on epithelial sodium channels in the distal convoluted tubule walls and increase reabsorption of sodium
causes water reabsorption by osmosis
increase in circulating blood volume
what is hyponatremia?
low sodium in the arterial blood
how can the RAA system cause vasoconstriction?
If BP is low, water can move from ISF to the blood as it passes through capillaries dilutes blood and causes hyponatremia
By raising systemic BP, RAA system pushes the water back into ISF
