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Definition:
Homeostasis refers to the maintenance of a constant internal environment.
3.1 Feedback mechanisms of homeostasis
1. Negative Feedback
2. Positive Feedback
3.2 Negative Feedback Mechanism
For the corrective mechanism to occur, there must be receptors detecting the change and effectors carrying out the corrective measures
Once the norm is reached, negative feedback in the form of a series of reactions that STOP the corrective mechanism occurs.
Negative feedback is involved in maintaining homeostasis in the human body.
Which system represents an efficient homeostatic system? Why?
Activity Two
3.3 Positive Feedback Mechanism
Positive feedback INCREASES the corrective mechanism that causes greater deviation from normal.
Example of positive feedback would be release of oxytocin during the childbirth process. During the initial stage of childbirth, oxytocin released by the hypothalamus of the brain stimulates release of nerve impulses that cause the hypothalamus of the brain to release more oxytocin. Oxytocin released causes the uterine contractions to increase in strength and frequency.
Positive feedback is not involved in maintaining homeostasis. Can you explain why this is so?
Activity Three
1. The normal concentration of glucose in the human blood is approximately 90 mg per 100 cm3 of blood. Even after the heaviest carbohydrate meal, blood glucose concentration rarely exceeds 150 mg per 100 cm3 of blood. Using principle of negative feedback, suggest how the body regulates and maintains a constant blood glucose concentration.
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