Question

Here is one more review question before we put these concepts together. Which statement is true about aldosterone secretion?

A. Aldosterone is secreted when low renal blood pressure activates the RAAS pathway and causes increased reabsorption of sodium from the distal tubule of the nephron and from the colon.

B. Aldosterone is secreted when high renal blood pressure activates the RAAS pathway and causes increased reabsorption of sodium from the distal tubule of the nephron and from the colon.

C. Aldosterone is secreted when low renal blood pressure activates the RAAS pathway and causes decreased reabsorption of sodium from the distal tubule of the nephron and from the colon.

D. Aldosterone is secreted when high renal blood pressure activates the RAAS pathway and causes decreased reabsorption of sodium from the distal tubule of the nephron and from the colon.

Answer 1

Ans A. Aldosterone is secreted when low renal blood pressure activates the RAAS pathway and causes increased reabsorption of sodium from the distal tubule of the nephron and from the colon.

Aldosterone is part of a group of linked hormones, which form the renin–angiotensin–aldosterone system (RAAS). This system is activated when there is decrease in blood flow to the kidneys following loss of blood volume or a drop in blood pressure (i.e low renal blood pressure) . Renin is an enzyme that leads to a series of chemical reactions resulting in the production of angiotensin II, which in turn stimulate aldosterone release. Aldosterone causes an increase in salt and water reabsorption into the bloodstream from the distal tubule of the nephron and from the colon

thereby increasing the blood volume, restoring salt levels and blood pressure.