Homeostasis Mechanisms PDF
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Tanta University Faculty of Medicine
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Summary
This document is about homeostasis, the body's ability to maintain constant internal conditions. It details the components involved in homeostatic mechanisms, such as receptors, effectors, and feedback systems (both negative and positive). Examples of homeostasis in action are also discussed, including regulation of body temperature and blood glucose levels.
Full Transcript
Definition Homeostasis means keeping the conditions in the internal environment constant, physically & chemically. Basic components of homeostatic mechanisms: 1. Receptors = detectors = sensors. 2- Afferent pathways. 3- Integrating center. 4- Efferent pathways. 5- Effector organs. Examples mechani...
Definition Homeostasis means keeping the conditions in the internal environment constant, physically & chemically. Basic components of homeostatic mechanisms: 1. Receptors = detectors = sensors. 2- Afferent pathways. 3- Integrating center. 4- Efferent pathways. 5- Effector organs. Examples mechanisms: of homeostatic 1- Regulation of body temperature. 2-Regulation of arterial blood pressure. (ABP). 3- Regulation of blood glucose level. Feedback control of the homeostatic mechanism: Definition: The feedback control is the control of a certain function by the resultant effect of that function. -Feedback control system may be negative or positive. (I) Negative feedback systems: -Definition: - It is a self-control system where the resultant effect of a function inhibits that function. -Negative feedback control operates continuously to maintain a certain parameter at a fixed constant level. - The change and correction in these systems are of the opposite signs. e.g. 1- Regulation of body temperature. 2- Regulation of body water & electrolytes. 3- Regulation of hormones. (II) Positive feedback systems: Definition: It is a control system where the resultant effect of a function stimulates that function. It magnifies the effect of a disturbance & results in instability. The positive feedback mechanism exaggerates any change. Some important examples for physical phenomena utilizing positive feedback are: a- In blood clotting mechanisms. b- During excitation of membranes (during depolarization of the cell membranes).
