Renal Hormones and Autocoids Flashcards
What are the 2 intrinisc renal mechanisms for autoregulation of GFR and renal blood flow?
myogenic mechanism tubuloglomerular feedback mechanisms
Myogenic mechanism
changing pressure of afferent arteriole
What does vasoconstriction of afferent arteriole cause
decreases RBF and GRF
How is GFR regulated
autoregulated
How is RBF related to GFR
autoregulated in parallel with GRF - dependent on GRF
tubluoglomerular feedback
mechanism for autoregulation when there is increased renal arterial pressure
What happens to fluid volume when there is incrased renal arterial pressure
less time to absorb water, larger than normal amt reaches loop of Henle per unit time
Function of Macula densa
sensor - senses flow via cilia as well as NaCl. chemical signals it releases inhibits release of renin
How can tubuloglomerula feedback help prevent excessive fluid losses after damage to kidney proximal tubules?
If proximal tubular reabsoprtion is reduced there is excessive water and NaCl going to distal tubule, then you will get vasoconstriction of afferent arteriole
Why do we have autoregulation?
because we want to be able to deal with the many changes in BP, we don’t want to have to involve the renal system every time that happens
how does autoregulation help patients with hypertension?
Helps compensate for the fact that nephrons are getting killed off
what are the vasodilator hormones?
Prostacyclins - PGE2 and PGI2
What are the vasoconstrictor hormones?
angiotension II, norepinephrine, vasopressin, endothelin
What drug inhibits prostaglandin synthesis
N-SAIDS
What releases renin
kidney
What releases angiotensin
liver
what releases aldosterone
adrenal cortex
What stimulates release of renin
low blood pressure
what cells release renin
juxtaglomerular cells
What division of the autonomic nervous system innervates the cells that produce renin
sympathetic stimulation of Beta1 adrenergic receptors
what happens to renin if you increases nervous stiulation
increases renin release
how does angiotensin II affect vascular smooth muscle
vasoconstriction
how does angiotensin II affect efferent arteriole
constriction
How does angiotensin II affect proximal tubule sodium reabsorption
increases
how does angiotensin II affect thirst
increases
how does angiotensin II affect release of ADH
increases
How does angiotensin II affect sympathetic tone
increases
What is the major source of erythropoietin
kidney (liver is minor source)
What is the major stimulation of erythropoietin
low oxygen
why is the kidney important in production of Bit D
it is converted to the active form in the kidney and is stimulated by PTH
what does active vit D do
increases absorption of calcium and phosphate in the intestine
function of PTH
stimulates final activation of vit D in kidney
increases renal-tubular calcium reabsoption
reduces proximal tubular reaborption of phosphate (increases phosphate excretion)
What is the source of FGF23
osteoblasts and osteocytes in bone
actions of FGF23 in kidney
decreases reabsorption of phosphate
decreases productino of calcitriol
what stimulates the secretion of FGF23
elevated levels of phosphate
calcitriol
How does chronic renal failure affect your pt’s bone
low GFR causes high phosphate in plasma
causes elevated PTH
causes increased bone resorption
