Which mechanism is NOT involved in human thermoregulation?

The mechanism that is not directly involved in human thermoregulation is respiration. While breathing does play a role in the overall metabolism and can influence body temperature to some extent due to heat exchange with the air, it is not a primary physiological mechanism for temperature regulation.

On the other hand, sweating is an essential mechanism for heat loss through evaporation, helping maintain a stable internal body temperature when external conditions are hot. Vasodilation, which is the widening of blood vessels, increases blood flow to the skin, facilitating heat loss. Behavioral changes, such as seeking shade, removing clothing, or adjusting activity levels, also contribute significantly to how we regulate body temperature in response to environmental changes. These mechanisms work together to maintain homeostasis, particularly in response to heat stress.