Correct option is D
Explanation -
Option a - Lowered threshold for start of sweating8
This does occur during heat acclimatization. With heat acclimatization, the body starts sweating earlier (i.e., at a lower core temperature). This earlier onset helps to cool the body more effectively, preventing excessive rises in core temperature.
Option b - Effective distribution of cardiac output
This also does occur. The body becomes more efficient at redistributing blood flow between the muscles and skin. More blood is directed toward the skin to facilitate heat loss via radiation and evaporation (sweating), while maintaining adequate blood supply to vital organs and muscles. It helps in efficient blood flow distribution ensures both cooling and metabolic needs are met.
Option c - Improved skin blood flow
This is another valid adaptation to increase heat dissipation through the skin. During acclimatization, blood vessels in the skin dilate more efficiently. This vasodilation increases skin blood flow, enhancing heat transfer from the body core to the skin surface. This increase skin blood flow and allows for better heat dissipation through the skin by convection, conduction, and evaporation.
Option d - Increased salt concentration of sweat – This does NOT occur.
During heat acclimatization, sweat becomes more dilute, not saltier. The body conserves salt to maintain electrolyte balance. During heat acclimatization, the sodium (Na⁺) concentration in sweat actually decreases. The sweat glands become more efficient at reabsorbing sodium and chloride ions before sweat reaches the skin surface. The result is more dilute sweat. It is a protective mechanism to conserve body salt and maintain electrolyte balance.
So, the correct answer is option d - Increased salt concentration of sweat.
