Aldosterone secretion is regulated by the presence of ________ in the circulation.a. Progesteroneb. Corticoglobulinc. ACTHd. angiotensin II
The correct answer is d
The correct answer is d. angiotensin II. Aldosterone secretion is primarily regulated by the renin-angiotensin-aldosterone system (RAAS).
The process begins with the release of renin from specialized cells in the kidneys called juxtaglomerular cells. Renin is released in response to various stimuli, such as decreased blood pressure or decreased sodium levels in the blood.
Renin then acts on its substrate, angiotensinogen, which is produced by the liver and present in the circulation. Renin cleaves angiotensinogen into angiotensin I.
Angiotensin I is relatively inactive and needs to be further converted to angiotensin II. This conversion is catalyzed by an enzyme called angiotensin-converting enzyme (ACE). ACE is primarily found in the lungs, endothelial cells, and other tissues.
Angiotensin II is a potent vasoconstrictor and also stimulates the release of aldosterone from the adrenal glands. Aldosterone acts on the kidneys to promote the reabsorption of sodium and excretion of potassium. This leads to an increase in blood volume and blood pressure.
So, the presence of angiotensin II in the circulation is a key regulator of aldosterone secretion. The other options mentioned in the question (progesterone, corticoglobulin, ACTH) do not directly influence aldosterone secretion. Progesterone is involved in the female reproductive system, corticoglobulin is not a hormone, and ACTH primarily stimulates the production of cortisol, not aldosterone.
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