British Sign Language Glossaries of Curriculum Terms

BSL Environmental Science Glossary - Homeostasis definition

Definition: Homeostasis is the regulation of the internal conditions in a cell or organism.

When conditions in the body change because of internal or external effects, the processes in the body will work to counter the change and bring conditions back to the normal level. In the human body, blood glucose concentration, body temperature and water levels are all controlled by homeostasis and kept within very narrow limits.

For example, body temperature: if it is hot outside, the body will respond by sweating, and blood vessels will rise towards the skin surface to help the body keep cool. If it is cold, the body will shiver, hair will rise on our skin, and the blood vessels will go deeper to help keep the body warm.

Water levels: if we do not drink enough water, the body will hold the water and produce less urine. If we drink sufficient water, we will have more urine.

Blood sugar level: the liver will take up the glucose molecules and store them as glycogen if the blood sugar level is high. If the blood sugar level is low, the liver will break down the glycogen molecules and release them as glucose.

It is vital to do this to maintain the optimum conditions for enzymes to work and for all body functions to take place efficiently. The body systems responsible for homeostasis are the nervous system and endocrine system.