Principles of HomeostasisAQA GCSE Biology: Flashcards

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Define homeostasis.

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Define homeostasis.: The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function.
Why is homeostasis important for enzymes?: Enzymes only work efficiently within a narrow range of conditions (temperature, pH); homeostasis keeps conditions within this range.
Name three things the human body controls through homeostasis.: Blood glucose concentration, body temperature and water levels.
What are the two types of response involved in control systems?: Nervous responses (fast, electrical) and chemical/hormonal responses (slower, longer-lasting).
What is a receptor?: A cell or organ that detects a stimulus.
Give three examples of coordination centres in the body.: The brain, the spinal cord and the pancreas.
What is an effector?: A muscle or gland that brings about a response to restore optimum levels.
What is the role of a coordination centre?: To receive and process information from receptors.
State the general pathway that describes how the body responds to a stimulus.: Stimulus → receptor → coordinator → effector → response.
Which two types of effector are there?: Muscles (which contract) and glands (which secrete hormones).
Why might a hormonal response take longer to have an effect than a nervous response?: Hormones travel in the blood to reach target organs, which is slower than electrical impulses along neurones.
What happens if internal conditions move outside the optimum range for enzyme action?: Enzyme activity slows, or at extreme conditions the enzyme may denature and stop working.
Is the pancreas a receptor, coordination centre, or effector?: A coordination centre.
Give an example of an effector that is a gland rather than a muscle.: The pancreas releasing insulin, or a sweat gland releasing sweat.
Why does the body need both nervous and hormonal control systems?: Nervous responses give fast, short-term reactions, while hormonal responses give slower, longer-lasting control — different situations need different response speeds.