Homeostasis is keeping the internal conditions of the body constant, so cells and enzymes work well. Body temperature, blood glucose and water levels are all controlled. Each control system has receptors that detect a change, a coordination centre (such as the brain or pancreas) that processes the information, and effectors (muscles or glands) that bring about a response.
Most controls use negative feedback: a change away from the normal level triggers a response that brings it back. If body temperature rises, the thermoregulatory centre in the brain makes you sweat and widens blood vessels near the skin (vasodilation), so more heat is lost. If you get too cold, you shiver, blood vessels near the skin narrow (vasoconstriction) and hairs stand up.
Worked example
Why does your skin look red after running?
- Running raises body temperature.
- Blood vessels near the skin widen (vasodilation).
Answer:More blood flows near the surface, losing heat, and the skin looks red.
Key words
- homeostasis
- keeping internal conditions constant
- negative feedback
- a change triggers a response that reverses it
- vasodilation
- widening of blood vessels
- coordination centre
- processes information and sends out responses
New questions every time.
NGSS-referenced: HS-LS1-3