Question

The atmospheric temperature varies over a wide range but human body temperature is more or less constant at $37^\circ C$. Explain.

Answer 1

One of the major constituents of the human body is water. So to raise the temperature of the human body it is required to raise the temperature contained in it. As the specific heat capacity of water is high it can minimise the temperature changes.

Complete step by step answer:
The human body consists of more than 60% water. So we can say that water is a major constituent of our body. Now the specific heat capacity of water is really high given by $4179.6Jk{g^{ - 1}}{K^{ - 1}}$. This means that at room temperature, the amount of heat required to raise the temperature of 1kg of water by 1K or $1^\circ C$ is $4179.6J$. So this is a huge amount of energy required per kg.
As this high amount of energy is not easily available in the surroundings, the water cannot raise its temperature and vary along with the atmospheric temperature. Thus the water in the human body minimizes the changes in its temperature. And this is the reason why the temperature of the human body can’t vary over a wide range of temperatures and remains more or less constant.

Note:
The specific heat capacities of substances vary with temperature and as well as with their state. The liquid state of water has one of the highest heat capacities among common substances. When a substance is undergoing a phase transition, that is, from solid to liquid or from liquid to gaseous, then the specific heat capacity is almost infinite as the heat goes into changing its phase rather than changing its temperature.