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Controlling temperature

The skin

The skin has many structures which allow it to function well as an organ which can regulate body temperature. It is important to maintain body temperature at 37°C as this is the temperature at which the body’s work best.

The skin is shown in this diagram.

A cross section of the human skin, labelled.

The hairs on the skin help to control body temperature. They lie flat when we are warm, and rise when we are cold.

When too warm:

Diagram showing how skin hairs lie flat when we are hot.
  • the hair erector muscle relaxes, lowering the hair
  • a thin insulating layer of air is trapped above the skin
  • more heat is lost to the environment

When too cold:

Diagram showing how skin hairs stand upright when we are cold.
  • the hair contracts, raising the hair
  • the hairs trap a thicker layer of air above the skin
  • the air the skin against heat loss