Homeostasis & Temperature Control (Cambridge (CIE) IGCSE Co-ordinated Sciences (Double Award)): Revision Note

The Skin & Homeostasis: Extended

Extended Tier Only

• Control of body temperature is a homeostatic mechanism

• Homeostasis is the maintenance of a constant internal environment

• This means that internal conditions within your body (such as temperature, blood pressure, water concentration, glucose concentration etc) need to be kept within set limits in order to ensure that reactions in body cells can function and therefore the organism as a whole can live

• The human body maintains the temperature at which enzymes work best, around 37°C

• If body temperature increases over this temperature, enzymes will denature and become less effective at catalysing reactions such as respiration

The Structure of the Skin

A cross-section of human skin

Temperature Regulation by the Skin

• Regulation is controlled by the brain which contains receptors sensitive to the temperature of the blood 

• The skin also has temperature receptors and sends nervous impulses to the brain via sensory neurones

• The brain responds to this information by sending nerve impulses to effectors in the skin to maintain the temperature within a narrow range of the optimum, 37°C

• Fatty tissue under the dermis acts as a layer of insulation to prevent too much body heat being lost through the skin

Homeostatic responses to changes in body temperature

Responses to changes in temperature: