NUR 612. Porth's Pathophysiology 9th Edition. Chapter 9 Disorders of Integrative Function Questions and Answers

Homeostasis The purposeful maintenance of a stable internal environment. A physiologic process opposing change. Operates by negative feedback mechanisms . Sensor Detects a change in the environment Integrator/comparator Sums and compares incoming data with setpoint Effector Returns the sense function to within the range of the setpoint Constancy of the internal environment Constancy in an open system requires mechanisms that act to maintain this constancy Steady-state conditions Require that tendency toward change automatically meet with factors resisting change Homeostasis Does not occur by chance but is the result of organized self-government. The regulating system determining homeostatic state consist of a number of operating mechanisms acting simultaneously. Functions of the body's control systems - Regulate cellular function - Control life processes - Integrate functions of the different organ systems Negative feedback When the monitored function or value decreases below the setpoint of the system , the feedback mechanism causes the function or value to increase. The reverse is also true Selye's stages of the Gen. adaptation syndrome Alarm stage, resistance stage, and exhaustion stage Alarm stage A generalized stimulation of the sympathetic nervous system and the HPA hypothalmic-pituitary-adrenal axis resulting in release of catecholamines and cortisol. Resistance stage The body selects the most effective and economical channels of defense