Question

Consider a person who is resting or doing light work. Is it fair to say that roughly one-third of the metabolic heat generated in the body is dissipated to the environment by convection, one-third by evaporation, and the remaining onethird by radiation?

Short answer

Answer: The assumption that one-third of the metabolic heat is dissipated through each mode - convection, evaporation, and radiation - might not be accurate for all situations. Heat dissipation rates vary depending on factors such as metabolic rate, clothing, environmental temperature, and humidity. It would be more accurate to say that the proportions of heat dissipation through each mode can vary depending on the specific conditions.

Step-by-step solution

Understand heat dissipation in the human body

Heat dissipation is the process by which the heat generated inside the human body is transferred to the environment. The main modes of heat transfer from the human body are convection, evaporation, and radiation.

Analyze convection

Convection is the process of heat transfer through a fluid (in this case, air) that's in direct contact with the skin. When the person's skin is warmer than the surrounding air, the heat from the body is transferred to the air. This is known as natural convection.

Analyze evaporation

Evaporation is the process by which liquid (sweat) on the skin evaporates, taking away heat from the body. This is a crucial mechanism for regulating body temperature, especially in hot conditions or during physical exercise.

Analyze radiation

Radiation is the process by which heat is emitted from the body in the form of infrared waves. This mode of heat transfer doesn't require a medium (such as air or water) and is responsible for keeping the body warm in cold environments, as well as dissipating some heat during rest or light work.

Evaluate the assumption

The assumption that one-third of the metabolic heat is dissipated through each mode - convection, evaporation, and radiation - might not be accurate for all situations. The heat dissipation rate through each mode depends on various factors such as the person's metabolic rate, clothing, environmental temperature, and humidity. For example, in a hot and humid environment, evaporation might play a more significant role in heat dissipation, while in a cold environment, radiation might play a more substantial role. Therefore, it would be more accurate to say that the proportions of heat dissipation through each mode can vary depending on the specific conditions.