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Saturday, 7 May 2011

Homeostasis

First, listen to the presentation: Homeostasis

1. Define 'homeostasis'.
Answer: The maintenance of a constant, internal environment.












2. What are the components of a homeostatic system?
Answer: sensor or receptor; control centre; effector; variable









3. Using blood glucose as an example explain how negative feedback works in the restoration of blood glucose levels after ingesting carbohydrates.
Answer: Following ingestion of the carbohydrates blood glucose levels rise, this is detected by the pancreas, insulin is released and blood glucose levels are lowered and insulin release is stopped by negative feedback.



4. Using blood pressure as an example identify the folowing: sensor or receptor; control centre; effector; variable.
Answer: sensor or receptor - baroreceptors ; control centre - medula oblongata/brain; effector - cardiovascular system; variable -
blood pressure.






5. Using falling blood pressure as an example explain how negative feedback works.
Answer: When blood pressure (BP) falls this is detected by the baroreceptors and the information is processed by the medulla oblongata. The cardiovascular system responds (increased heart rate and vasoconstriction) BP rises to within mormal limits and this stops the increase in BP through negative feedback.

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