Control of Body Temperature (AQA GCSE Biology)

Monitoring of Body Temperature

• The human body needs to maintain a temperature at which enzymes work best, around 37°C

• Processes such as respiration release energy as heat; and the body loses heat energy to its surroundings – the energy gained and lost must be regulated to maintain a constant core body temperature

• Body temperature is monitored and controlled by the thermoregulatory centre in the brain

• The thermoregulatory centre contains receptors sensitive to the temperature of the blood

• The skin contains temperature receptors and sends nervous impulses to the thermoregulatory centre

Human skin contains structures involved in processes that can increase or reduce heat loss to the surroundings

Controlling Body Temperature

• If the body temperature is too high, blood vessels dilate (vasodilation) and sweat is produced from the sweat glands

• Both these mechanisms cause a transfer of energy from the skin to the environment, cooling the body down

Responses in the skin when the body temperature is too high and needs to decrease

• If the body temperature is too low, blood vessels constrict (vasoconstriction), sweating stops and skeletal muscles contract (shiver)

• These mechanisms reduce heat loss to the surroundings (with skeletal muscle contraction increasing heat released in the body)

Responses in the skin when body temperature is too low and needs to increase

Examples of Body Temperature Control

Higher tier only

• The mechanisms described above lower or raise body temperature

• In the exam, you may be given examples of different contexts in which the body temperature needs to decrease (when someone is too hot) or increase (when someone is too cold)

• Learn the following concepts to ensure you can suggest what changes are happening and why:

Body temperature regulation summary table

Remember homeostasis involves the maintenance of constant internal environment; temperature control is an example of negative feedback