Homeostatic control systems

Cells and organisms function best when their internal conditions remain suitable. Homeostatic control systems help maintain these conditions, even when the internal or external environment changes. In humans, regulated conditions include blood glucose concentration, body temperature and water levels. Keeping them suitable supports enzyme activity and other cell functions.

Parts of a homeostatic control system

A change in the internal or external environment is a stimulus. Receptor cells detect stimuli and send information to a coordination centre. The coordination centre processes the information and coordinates a response. The brain, spinal cord and pancreas are examples of coordination centres.

The response is carried out by effectors, such as muscles or glands. Communication between the parts of the system can use nervous signals or chemical messengers. The effectors’ actions help restore suitable conditions.

For example, if body temperature rises, receptors detect the change and the brain coordinates a response. Sweat glands produce sweat; as it evaporates from the skin, it helps cool the body.

Homeostasis

Cells need suitable internal conditions to function. Homeostasis is the control of an organism’s internal conditions to keep them within suitable ranges.

When an internal condition changes, the organism detects the change and produces a response that helps bring the condition back towards a suitable range. This control keeps internal conditions relatively stable, even when the surroundings or the organism’s activities change. It does not mean that conditions remain exactly constant.

For example, exercise can cause a person’s body temperature to rise. The body detects the rise and responds by producing sweat. As sweat evaporates from the skin, it removes heat, helping the body temperature return towards a suitable range.