Thermoregulation

• 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.
• 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.
• 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).