renal endocrinology Flashcards
(22 cards)
what are the features of the JG apparatus ?
has the macula densa - part of the distal convoluted tubule
JG cells
release renin
what is the origin of JG cells ?
modified cells of the afferent arteriole
what is the main job of the RAAS?
increase salt and water retention and increase blood pressure
how is the RAAS activated ?
renin secreted from the JG cells , changes the angiotensinogen to angiotensin 1 , with ace inhibitors this is converted to angiotensin 2
what are the main functions of angiotensin 2 ?
renal sodium and chloride resorption even though there is an increase in GFR
efferent arteriole vasoconstriction
adrenal aldosterone secretion
what are the triggers for renin release ?
1- low perfusion pressure
2- low sodium chloride delivery - part of tubuloglomerular feedback
3- sympathetic activation
how does angiotensin II increase the sodium resorption ?
through 2 mechanisms
1- increased proximal tube resorption via the capillary effect
2- direct proximal tubule resorption through sodium hydrogen exchange
3- promotion of aldosterone release
what are the functions of aldosterone ?
increases the NA/KATPase proteins
increases the number of Enac channels
promotes potassium secretion
promotes hydrogen secretion
what are the stimulants for aldosterone ?
angiotensin 2
high potassium levels
what is the effect of ACE inhibitors and ARBS on the RAAS ?
1- ACE inhibitors block the conversion of angiotensin 1 into 2 abd lower blood pressure
2- ARBS block the effect of angiotensin 2 and again lower blood pressure
what is the effect of beta blockers on the RAAS ?
block sympathetic stimulation of the JG apparatus , so they block renin release, and lower blood pressure
what is the ffect of aldosterone antagonists and potassium sparing diuretics ?
1- aldosterone antagonists lower blood pressure , they increase potassium levels and hydrogen levels
2- potassium sparing diuretics - these inhibit ENaC
what hormones are associated with opposing the function of RAAS ?
ANP
BNP
they are vasodilators and promote diuresis
what is the association between heart failure and the RAAS ?
in heart failure there is a decreased cardiac output , decreased perfusion and so decreased renal perfusion
this activates the RAAS system
so increased ANP/BNP is associated with increased Sympathetic nervous system activation and RAAS
what are the effect of the PTH in the kidneys ?
increased calcium resorption
decreased phosphate resorption
increased vitamin D production
what is the effect of PTH on cells of the proximal tubules ?
PTH inhibts the transporter responsible for the entry of phosphate , hence the increased phosphate excretion
what is the effect of PTH on the distal tubule cells ?
PTH activates the sodium calcium co transporter to increase calcium resorption
where does the activation of vitamin D occus in the kidney ?
activation of 1 alpha hydroxylase 1,25
what is the main function of erythropoeitin ?
hormone made by the kidney used for the stimulation of production of red blood cells in the bone marrow
what are the triggers of EPO production ?
hypoxia
what is the consequence associated with EPO and renal failure ?
pts with renal failure have normocytic anemia due to lack of EPO production
where in the kidney is dopamine secreted from ?
from the cells of the proximal tubule
promotes natruiresis
acts as a vasoconstrictor in high doses
