2.5 Controlling Conditions

The internal environment of the body is controlled by the nervous system and hormones. The maintenance of a constant internal environment is called homeostasis. Here are some of the internal conditions that need to be controlled.                                                    Ion (salts) content of the body

• Ion levels are controlled to protect cells from too much water entering or leaving them. Ion content is controlled by the loss of ions from:
• the skin - through sweating
• passing urine - produced by the kidneys.

Temperature of the body. This is controlled to maintain the temperature at which enzymes work best. Body temperature is controlled by sweating, shivering, and controlling blood flow to the skin.

Blood sugar levels. This is controlled to provide cells with a constant supply of energy. Blood sugar level is controlled by the release and storage of glucose controlled by insulin.