5.1: Homeostasis
Not started yet — this one needs some love.
Homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.
Homeostasis maintains optimal conditions for enzyme action and all cell functions.
In humans, homeostasis includes control of blood glucose concentration, body temperature and water levels.
Automatic control systems may involve nervous responses or chemical responses.
Receptors are cells that detect stimuli, which are changes in the environment.
Coordination centres, such as the brain, spinal cord and pancreas, receive and process information from receptors.
Effectors are muscles or glands that bring about responses which restore optimum levels.
Common exam mistakes
Do not stop at "stable internal conditions"; include optimum conditions for enzyme action or cell function when asked for the importance of homeostasis.
Do not define homeostasis as control of the external environment; it regulates internal conditions.
Receptors detect stimuli, coordination centres process information, and effectors bring about responses; keep these roles separate.
A muscle or gland is an effector, not a receptor or coordination centre.