In short
Homeostasis is the keeping of the conditions inside the body, such as temperature, water and sugar levels, steady and within narrow limits even when the outside conditions change.
It works by negative feedback: a change is detected and the body acts to reverse it. If body temperature rises, you sweat and the skin blood vessels widen, so heat is lost. If it falls, you shiver and the vessels narrow. Blood glucose is controlled by the hormones insulin and glucagon. The kidneys control water and salt balance.
After a meal, blood glucose rises and the pancreas releases insulin. The liver stores the extra glucose, and the level falls back to about per of blood.
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