RAAS and other receptor actions

Question 1

Explain the release of aldosterone and what aldosterone and what aldosterones effects are?

1. What stimulates renin release and where?
2. cascade that leads to aldosterone release? where do the peptides/proteases come from?
3. effects of aldosterone? where?
4. overall effect of aldosterone 5. besides renin what else causes aldosterone release

Answer 1

1. Renin is released by the granular cells in the kidney by signals related to volume depletion.
   - decreased blood pressure in the afferent arteriole sensed by the granular cells(mechanoreceptors)
   - SNS input via epi(b1) on granular cells
   - Decreased NaCl in lumen of nephron sensed by macula densa in the thick ascending loop of henle.
2. angiotensin from liver just hanging around.

• Renin secreted from kidney is response to above mechanisms
• angiotensin 1
• ACE from lung endothelium
• angiotensin 2
• adrenal cortex secretes
• aldosterone

3. aldosterone increase the reabsorption of NaCl (water with it) in

• thick ascending loop of henle
• DCT
• Collecting duct (increased k excretion)

4. Overall effect increased intravascular fluid volume
5. increased Potassium also stimulates aldosterone release

Question 2

What does angiotensin 2 cause physiologically when released?

Answer 2

• renal proximal tubule increase sodium absorption
• renal efferent arteriole vasoconstriction to maintain GFR
• hypothalamus release ADH
• adrenal cortex release aldosterone