HomeostasisThe conditions inside our body must be very carefully controlled if the body is to function effectively. Homeostasisis the maintenance of aconstant internal environment. The nervous system andhormonesare responsible for this.
Body temperature This is controlled to maintain the temperature at which the body’senzymeswork best, which is usually 37°C.
Blood sugar level This is controlled to provide cells with a constant supply ofglucoseforrespiration. It is controlled by the release and storage of glucose, which is in turn controlled by insulin.
Water content This is controlled to protect cells by stopping too much water from entering or leaving them. Water content is controlled by water loss from:
the lungs - when we exhale
Regulating body temperatureThe human body is designed to function most efficiently at 37ºC. If you become too hot or too cold, there are ways in which your body temperature can be controlled.
Too hot When we get too hot:
Sweat glands in the skin release more sweat. The sweat evaporates, removing heat energy from the skin.
Blood vessels leading to the skin capillaries become wider - they dilate - allowing more blood to flow through the skin, and more heat to be lost.
Too cold When we get too cold:
Muscles contract rapidly - we shiver. These contractions need energy from respiration, and some of this is released as heat.
Blood vessels leading to the skin capillaries become narrower - they constrict - letting less blood flow through the skin and conserving heat in the body.
The skin The hairs on the skin also help to control body temperature. They lie flat when we are warm, and rise when we are cold. The hairs trap a layer of air above the skin, which helps toinsulate the skin against heat loss.