BRAINCAKEHomeostasis
Homeostasis is the maintenance of a constant internal environment within narrow limits, despite changes in the external or internal environment.
'Constant' does not mean fixed. Each variable fluctuates around a set point (norm), in a state of dynamic equilibrium. Variables controlled in mammals include:
- core body temperature (about 37 °C in humans);
- blood glucose concentration;
- the water potential of the blood (osmoregulation);
- blood pH and carbon dioxide concentration.
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Key terms in this lesson
- water potential
- A measure of the tendency of water molecules to move out of a solution, which determines the direction of osmosis.
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All 30 lessons in Chemical Control · All Edexcel A-level Biology topics