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Physiology · General physiology: heat acclimatisation
Sample itemAfter two weeks of working in a hot, humid factory, a worker begins sweating earlier and more profusely, but his sweat is much more dilute in sodium. Which hormone mediates the lower sweat sodium concentration?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
D. Aldosterone
In heat acclimatisation, rising aldosterone acts on the sweat duct to reabsorb sodium and chloride, so the sweat becomes dilute and less salt is lost. Sweat volume and onset also improve. This is a protective change that preserves body sodium during prolonged sweating.
Option by option
A. Thyroxine
Thyroxine raises heat production and does not control duct sodium reabsorption.
B. Vasopressin
Vasopressin conserves water through the kidney and does not govern sweat gland sodium handling.
C. Atrial natriuretic peptide
Atrial natriuretic peptide promotes sodium loss and would make sweat saltier, not more dilute.
D. Aldosterone (correct)
Correct. Aldosterone increases sodium reabsorption in the sweat duct.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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