MathsGradeUp logoMathsGradeUp
BiologyGCSE, IGCSE & A Level

What is homeostasis?

Homeostasis is the maintenance of a constant internal environment despite changes in external conditions.

Homeostasis explained

Control systems have a receptor to detect change, a coordination centre to process it, and an effector to bring about the correction — usually by negative feedback.
Blood glucose, body temperature and water balance are the standard examples, controlled by insulin and glucagon, the skin and hypothalamus, and ADH respectively.

Key formula

stimulus → receptor → coordination centre → effector → response

Worked example

Rising blood glucose triggers insulin release, so liver and muscle cells take up glucose and store it as glycogen.

Examiner tip

Name the specific hormone, organ and effect. Vague answers about 'the body balancing itself' score nothing.

Homeostasis: common questions

What is negative feedback?
A response that reverses a change, returning the condition to its set point — the mechanism behind almost all homeostasis.
Why is homeostasis important for enzymes?
Enzymes need a narrow temperature and pH range to keep their active site shape and work at full rate.

Related terms

Enzyme

An enzyme is a biological catalyst — a protein that speeds up a specific reaction by lowering its activation energy.

Active transport

Active transport moves substances against a concentration gradient using carrier proteins and energy from ATP.

Osmosis

Osmosis is the net movement of water molecules from a dilute solution to a concentrated one through a partially permeable membrane.

Practise biology on MathsGradeUp

Take homeostasis from a definition to full marks with exam-board question banks, revision notes and instant step-by-step feedback from Study Coach.

Biology revision notesPractice questionsCreate a free account

Related on MathsGradeUp

Keep studying

Practise it