Answer:
The receptor senses changes in the environment and responds by sending information (input) to the control center along the ascending pathway. The control center analyzes the input, determines the appropriate response, and activates the effector by sending information along the descending pathway. When the response causes the initial stimulus to decline, the homeostatic mechanism is referred to as a negative feedback mechanism. When the response enhances the initial stimulus, the mechanism is called a positive feedback mechanism. Negative feedback, mechanisms are much more common in the body.
Explanation:
Homeostasis is the adaptation of living organisms or systems to new conditions in the environment by auto-regulation. Through this mechanism, an equilibrium state can be maintained in spite of any changes. This adjustment in the physiological system is called homeostatic regulation and it is composed of three parts: the receptor, the control center, and the effector.
The receptors receive information from the environment about something changing and transmit that information to the central nervous system (control center). This pathway is defined as the ascending pathway. Information is processed in the control center which handles many sensory signals, evaluates them, compares them and uses them for decision making. After that, an efferent neuron is stimulated to carry information from the central nervous system to the effector cells of the target organ. The effector may be muscle or glandular tissue. This pathway is defined as the descending pathway. Finally, the target organ responds.
There is negative feedback when the response declines the initial stimulus, which is the most common mechanism in the body. There is positive feedback when the response enhances the initial stimulus, which might be very nocive to the organism.
