A recruit completes four weeks of training in a hot desert environment. Compared with his unacclimatized state, which pattern of change characterizes his sweat response?

• A Higher sweat volume with lower sodium concentration ✓
• B Lower sweat volume with higher sodium concentration
• C Lower sweat volume with unchanged sodium concentration
• D Higher sweat volume with higher sodium concentration

Explanation

Heat acclimatization produces earlier onset of sweating and increases maximal sweat output several fold, while aldosterone-mediated upregulation of ductal sodium reabsorption lowers sweat sodium concentration, conserving salt. This combination permits greater evaporative cooling with less electrolyte depletion. The opposite pattern, low volume with salty sweat, describes the unacclimatized individual and predisposes to heat cramps.

Reference: Guyton and Hall Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.