Question

Given the following events invloved in the regulation of blood volume, which of the following answers best represents the order in which these events occur?
1. sodium reabsorbed from distal tubules and collecting ducts
2. secretion of renin from juxtaglomerular apparatus
3. secretion of aldosterone
4. decrease in blood volume
5. prodiction of angiotension II

a) 4,5,2,1,3
b) 4,2,5,3,1
c) 4,2,5,1,3
d) 1,4,5,2,3
e) 2,3,4,1,5

Answer 1

Answer:

The correct answer will be option-B

Explanation:

Kidneys help maintain the blood volume by activating renin-angiotensin-aldosterone (RAAS) system. The activation of the system increase sodium retention which helps reduce the amount of water lost into the urine.

The RAAS system is activated when the receptors sense the decrease in the volume of the blood. This leads to the production of renin from the juxtaglomerular cells of the kideny. The renin help converts the inactive angiotensin to angiotensin I and angiotensin II by ACE enzyme.

Angiotensin II stimulates the production of aldosterone from the adrenal cortex which promotes the retention of sodium from tubules and maintains the long term blood pressure.

Thus, Option-B is the correct answer.

Activation of the renin-angiotensin-aldosterone (RAAS) system causes increased sodium retention by the kidneys, which leads to reduced water loss into the urine and therefore blood volume expansion. RAAS activation occurs during heart failure, which leads to fluid retention in the body. RAAS activation also occurs with renal artery stenosis, which is one cause of secondary hypertension.