How does the body control its temperature?

Thermoregulation is an example of homeostasis - the process by which the body maintains an optimum state. The body must maintain a stable temperature because extreme lows and highs of temperature can affect the operation and structure of proteins, including the shape of the activate sites of vital enzymes. Thermoregulation occurs by negative feedback. This is when the body reverses a departure in the internal environment from the optimum. The internal change is detected by sensory receptors and then signalled to effector cells by a communication system, such as the neural or hormonal systems. These effector cells produce a response which reverses the change.

The hypothalamic thermoregulatory centre monitors the temperature of the blood and if this drops below an optimum temperature, the centre sends signals via the neural and hormonal systems to the skin, liver and muscles. As a result, the rate of exergonic reactions in liver cells is increased and the skeletal muscles contract to generate heat, increasing one's body temperature. If the thermoregulatory centre registers an increase in body temperature away from the optimum it will signal the skin to secrete sweat, hairs on the skin to lie flat and the skin capillaries to vasodilate so that more heat can be radiated from the skin.

There are also peripheral temperature receptors in the skin that monitor the temperature of the extremities and then this information is passed onto the thermoregulatory centre. If the centre registers that there is a change in temperature in the external environment, behavioural mechanisms can be employed to maintain an optimum body temperature, such as orientating the body towards the sun or hiding in a burrow.