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LONG ANSWER! PLEASE ANSWER ALL PARTS The Renin-Angiotensin-Aldosterone system pl

ID: 81869 • Letter: L

Question

LONG ANSWER! PLEASE ANSWER ALL PARTS

The Renin-Angiotensin-Aldosterone system plays an important role in correcting loss of ECF volume in the body. The kidney plays an important role in this regulation.

- Starting with loss of extracellular volume (and concomitant loss of arterial pressure), succinctly describe the non-neuronal mechanisms that lead to ultimate Angiotensin-II production/release. Make sure to name the key renal structures and enzymes involved in this process. Also, make sure to include both the effects of NaCl and afferent arteriole pressure in this auto-regulatory process.

- Now describe how the sympathetic nervous system can get involved in the regulation you discussed in part “a” (i.e. neuronal mechanism).

- Describe 5 ways in which Angiotensin-II tries to correct the loss of blood volume.

Explanation / Answer

When there is a drop in the blood pressure and the fluid volume,

Angiotensin II:
(a) causes arteries to constrict and increases cardiac output resulting in an increase in blood pressure and volume;
(b) Decreases glomerular filtration rate resulting in water retention
(c) Increases thirst
(d) It activates the hormone aldosterone which causes the distal tubules to reabsorb sodium and water, which increases blood volume
(e) It releases ADH which increases sodium reabsorption from the medulla of the kidney