Grades 3–5 · Organisms
Why do we sweat when hot and shiver when cold?
Your body is always producing heat as its cells use chemical energy. It also exchanges heat with its surroundings. Temperature sensors in the skin and deeper inside the body provide information to the brain, which helps coordinate responses.
In the diagramSweat loses heat; shivering produces heatSelected response, not a temperature predictionSkin surfaceEvaporation carries energy awayBlood flow and other responses also matter.
When the body needs to lose more heat, sweat glands can put watery sweat onto the skin. Water needs energy to evaporate into the air. Some of that energy comes from the skin, helping it cool. Sweat that stays liquid or drips away does not provide the same evaporative cooling. Humid air can make evaporation harder.
When the body needs to conserve or produce heat, blood flow near the skin can change and muscles may begin shivering. These repeated contractions use chemical energy and release heat, even without useful movement across the room. Sweating and shivering are parts of a larger control system. The diagram shows their mechanisms, without calculating a person’s temperature.
About this explanation
Starting knowledge: Know that evaporation changes liquid water into water vapor.
Sources
- OpenStax, Anatomy and Physiology 2e — Homeostasis