Organisms keep internal conditions stable — Science, 14–17 years
Homeostasis uses sensors, control centres and responses to keep variables such as temperature and blood sugar within safe limits.
Stability through constant adjustment
Your body does not keep every condition at one exact number. It detects changes and makes small corrections around a useful range. This balance, called homeostasis, lets cells work even when the outside temperature, food or activity changes.
Why control the inside?
Chemical reactions in cells need conditions that are not too far from ideal. Without control, a fever, dehydration or a sudden rise in blood sugar can disrupt enzymes and damage tissues. Feedback systems solve this problem by linking a change to a response that reduces it.
Cooling after exercise
During a run, muscles release extra heat, so body temperature rises. Temperature sensors detect this; the brain signals sweat glands to make sweat, and skin blood vessels widen. Evaporation and increased blood flow transfer more heat away, bringing temperature back towards its range.
Negative feedback is not bad feedback
The word “negative” can sound harmful, so it is easy to assume the system makes the change worse. Here it means the response opposes the original change. Sweating after overheating is negative feedback because it reduces the temperature rise.
Understanding diabetes
After a meal, blood glucose rises. Insulin helps body cells take up glucose and helps the liver store some, bringing the level down. In diabetes, insulin production or response is impaired, so monitoring, food choices and treatment help manage the disrupted control system.
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