Homeostasis PDF

# Homeostasis Homeostasis is the process where body internal environment is regulated and maintained. The internal environment is the water-based medium in which body cells exist. Cells are bathed in fluid called interstitial or tissue fluid. They absorb nutrients from the surrounding interstitial...

# Homeostasis Homeostasis is the process where body internal environment is regulated and maintained. The internal environment is the water-based medium in which body cells exist. Cells are bathed in fluid called interstitial or tissue fluid. They absorb nutrients from the surrounding interstitial fluid. ## Control Systems of Homeostasis Homeostasis is maintained by control systems that detect and respond to changes in the internal environment. A control system has three (3) key components and they are: - Detector - Control Center - Effector ### Detector A Detector or sensor that senses any change in pressure, concentration, volume etc which then integrates the incoming information to the control center. ### Control Center The control center determines the limit within which the variable factor should be maintained. If it receives an input from the detector, when the incoming signal indicates that an adjustment is needed, the control center responds and its output to the effector is change. ### Effector The effector are the structures that change the observed and the integration is being received. ## Feed Back Mechanism Feedback mechanisms are the mechanism of action by which changes occur (adjustment). The feedback mechanism are: - Negative feedback mechanism - Positive feedback mechanism ### Negative Feedback Mechanism Negative feedback means any movement of such a control or reverse in such a way as to arrest the change or revert it to a way of change. After receiving a message, effector send negative feedback signal back to the system. Now, the system stabilizes its function and makes an attempt to maintain homeostasis. ## Examples of Positive Feedback Mechanism One of the examples of positive feedback mechanism is during blood clotting and labor. ### Blood Clotting - Injury to blood vessel and bleeding. - Stoppage of blood flow - Formation of prothrombin - Conversion of prothrombin into thrombin. - Conversion of fibrinogen into fibrin - Blood clots ### Labor - Contraction of the uterus. - Movement of the fetus in the uterus. - Cervix dilated - Release of oxytocin - Movement of the fetus through the cervix. - Stimulation of receptors. - Increase of impulses from the receptors. - Constriction ## Role of Various System of The Body in Homeostasis 1. **pH:** The pH of the ECF has to be maintained at a critical value of 7.4. The tissue cannot survive if it is alkaline, decrease in pH lead to acidosis and increase in pH lead to alkalosis. The respiratory system, blood and the kidney regulate pH. 2. **Temperature:** The temperature of the body is regulated by the skin, respiratory system, digestive system, skeletal muscles, and the nervous system. 3. **Nutrients:** Adequate nutrient is being supplied to the various tissue by the digestive system and the circulatory system. 4. **Body Metabolism:** Body metabolism is being regulated by the endocrine and nervous tissue. 5. **Water and Electrolyte:** The salivary gland, kidney, skin, and gastro- intestinal tract regulate water and electrolyte. ## Mechanism of Action of Homeostasis Feedback mechanisms are the mechanism of action by which changes occur (adjustment). The feedback mechanism are: - **Negative feedback mechanism:** The system reacts in such a way as to arrest the change or revert it to a way of change. - **Positive feedback mechanism:** The system reacts in such a way as to increase the change in the same direction. The intensity of change is less common than the negative feedback. However, it has its own significance particularly during emergency conditions.