Renin- Angiotensin- Aldosterone system Flashcards
Describe the ultimate process of Renin release
The juxtagomerular cells sense a decrease in blood pressure
The macula densa cells sense a decrease in sodium levels.
Both of these events trigger sympathetic activity on B2 cells causing the release of Renin.
Describe the steps of activating Angiotensinogen
Angiotensinogen is floating in the blood.
Renin activates it to ANG I that is then acted on in the lungs by ACE. (also breaks down bradykinins)
ANG II is then able mediate its effects.
What effects does ANG II have on smooth muscle?
ANG II Acts via V2 receptors at the endothelial cells of blood vessels resulting in vasoconstriction and increased blood pressure.
What effects does ANG II have on the glomerulus?
Constricts the efferent arteriole to preserve renal function in low volume states.
What effects does ANG II have at the adrenal gland?
Increases the formation of aldosterone from the cortex..
Aldosterone increases sodium channel and Na/K+ pump insertion in the principle cells.
Also increases K+ and H+ excretion.
Ultimately creates a favorable ion gradient for water absorption.
What effects does ANG II have on the pituitary?
Acts on the posterior pituitar to release ADH (vassopressin)
ADH increases aquaporin insertion into principle cells for water absorption.
What effect does ANG II have at the proximal convuluted tubule?
Increases sodium/hydrogen activity
Increases sodium and HCO3 reabsorbtion.
What effect does ANG II have on the hypothalamus?
Increases thirst
Describe AT II effects on the baroreceptors
Affects baroreceptor function limiting reflex bradycardia.
Helps maintain blood volume and blood pressure.
Describe ANP and BNP effects and where they are released from.
ANP is released from atria
BNP released from ventricles
Both respond to INCREASED VOLUME act as a check on renin-angiotensin-aldosterone system.
Relaxes vascular smooth muscle via cGMP increasing GFR and decreasing renin.
Describe the juxtaglomerular apparatus
Consists of mesangial cells, JG cells (modified smooth muscle of afferent arteriole) and the macula densa (NaCL sensitiviy)
JG cells secrete renin based on blood pressure and sympathetic tone.
Macula densa sense sodium decreases and release adenosine for vasoconstriction.
Describe how the juxtaglomerular apparatus maintains GFR
Renin-angiotensin-aldosterone pathway
How can beta blockers lower blood pressure?
Inhibit the B1 effects at the kidneys in the JGA thus less renin released.`
What effect do the kidneys have on blood formation?
Increases erythropoiten secretion
What effect do the kidneys have on vitamin D?
PCT cells convert 25-OH vit D from the liver to the active form of D 1,25-OH2
Occur via PTH activating 1alpha-hydroxylase.
