Homeostasis & ResponseTopic Summary
Knowledge Organiser: Homeostasis Introduction
Part of Homeostasis Intro · GCSE GCSE Biology revision
This topic summary covers Knowledge Organiser: Homeostasis Introduction within Homeostasis Intro for GCSE Biology. Topic 1: Homeostasis Intro It is section 13 of 13 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 13 of 13
Practice
15 questions
Recall
20 flashcards
Knowledge Organiser: Homeostasis Introduction
Key Terms
- Homeostasis — regulation of internal conditions to maintain optimum conditions for function
- Receptor — detects a change (stimulus)
- Coordination centre — processes information; sends instructions to effector
- Effector — muscle or gland; carries out the corrective response
- Negative feedback — response opposes and reverses the original change
- Internal environment — conditions inside the body (temperature, glucose, water, pH)
- Optimum conditions — the specific temperature, pH, and glucose level at which enzyme activity (and therefore cell function) is at its maximum rate
Key Facts
- Body temperature maintained at 37°C (enzyme optimum)
- Blood glucose range: 4–8 mmol/L
- Blood pH range: 7.35–7.45
- Control loop: receptor → coordination centre → effector → response → return to normal
- Nervous system: fast, short-lived, specific target
- Endocrine system: slower, long-lasting, widespread effects
- Coordination centres: hypothalamus (temp), pancreas (glucose), kidneys (water)
The Control Loop
- 1. Condition deviates from normal
- 2. Receptor detects the change
- 3. Coordination centre processes signal
- 4. Effector produces corrective response
- 5. Response opposes the original change
- 6. Condition returns to normal range
- 7. Effector response switches off
Common Mistakes
- Saying the body "keeps conditions constant": Homeostasis maintains conditions within a narrow range — conditions fluctuate slightly around a set point. The body does not keep any variable perfectly constant; it uses negative feedback to return it to the normal range.
- Confusing receptor and effector: A receptor detects a change and sends a signal. An effector (muscle or gland) brings about the corrective response. Students often describe the effector doing the detecting or the receptor making the response.
- Forgetting to name all three components of a control system: Full marks require naming the receptor, coordination centre, AND effector. Omitting any one of these three components in a "describe the negative feedback loop" answer will lose a mark.
- Describing positive feedback as homeostasis: Homeostasis uses negative feedback, where the response opposes the original change. Positive feedback amplifies the change and is not part of homeostasis — do not confuse the two.