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Homeostasis
OCR A2 Biology F214
| Question | Answer |
|---|---|
| Homeostasis | The maintenance of the internal environment in a constant state despite external changes |
| Negative feedback | A process that brings about the reversal of a change in condition. This ensures that the optimum state is maintained |
| Positive feedback | This is a process that increases any change detected by the receptors. It tends to be harmful and is less common that negative feedback. The production of the hormone oxytocin during labour is an example |
| Ectotherm | An organism that relies on external sources of heat to regulate its body temperature |
| Endotherm | An animal that can use internal sources of heat such as the heat produced from metabolism e.g. in the liver to regulate body temperature |
| Thermoregulatory centre | Located in the hypothalamus of the brain of endotherms. It monitors the temperature of the blood and sends signals to reverse any change away from the core temperature |
| Vasodilation | The precapillary sphincter is open and this allows more blood to flow through the capillary bed. Thus more blood flows near the skin surface and heat is lost by radiation |
| Vasoconstriction | The precapillary sphincter is closed and this means that less blood flows through the capillary bed. Therefore less blood flows near the skin surface and less heat is lost by radiation |
Created by:
abushill
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