Select a homeostatic challenge and watch the body's negative feedback response unfold step by step.
Negative Feedback Loop
Key Concepts
Negative Feedback
A mechanism where a change in a variable triggers a response that reverses (opposes) the change, bringing the variable back towards the set point. This maintains a stable internal environment.
Positive Feedback
A mechanism where a change amplifies itself — the response increases the deviation from normal. Examples: oxytocin during labour, blood clotting cascade. These are rare and usually short-term.
Thermoregulation
Core body temperature maintained at ~37°C. The hypothalamus acts as the thermostat, detecting blood temperature changes and triggering vasodilation/vasoconstriction, sweating/shivering.
Blood Glucose Regulation
Maintained by insulin (β cells → lowers glucose) and glucagon (α cells → raises glucose) from the islets of Langerhans in the pancreas. These are antagonistic hormones.
Edexcel exam tip: When describing negative feedback, always state: (1) the normal/set point, (2) what detects the change (receptor), (3) the coordination centre, (4) the effector and its response, (5) that the variable returns to normal. Five marks, five steps.