XII. Stress and the General Adaptation Syndrome

A. Homeostatic mechanisms attempt to counter the everyday stresses of living 1. If successful it maintains normal physiological limits of chemistry, temperature, and pressure 2. If stress is extreme, unusual, or long lasting, the normal mechanisms may not be enough triggering a wide set of changes called the stress response or GAS

3. This system does not maintain a 3. This system does not maintain a constant environment but prepares for an emergency

B. Stressors 1. Stimuli that produce general adaptation syndrome are called stressors a. could include heat, cold, surgery, poison. Infection, fever, and emotion 2. When a stress occurs, the hypothalamus initiates GAS through two paths

a. First produces an immediate set response called the alarm reaction b. The second is called resistance which is slower but last longer

C. The alarm reaction 1. The alarm reaction is initiated by hypothalamic nerve impulses to autonomic nerve system and adrenal medulla 2. Causes immediate but brief fight or flight by increasing circulation, catabolism, and decreasing nonessential functions

D. Resistance reaction 1. Regulated by hormones from the hypothalamus a. Hormones are corticotropin releasing, growth hormone releasing and thyrotropin releasing hormones 2. CRH stimulates the anterior pituitary to secrete adrenocorticotropic hormone which stimulates the adrenal cortex

3. Are long-term and accelerated 3. Are long-term and accelerated catabolism to release energy to decrease stress 4. Glucocorticoids come in increased concentration and create wide physiological effects

E. Exhaustion 1. Exhaustion results from dramatic changes during alarm and resistance 2. Caused by a loss of potassium, depletion of adrenal glucocorticoids, and weakened organs 3. It can kill

F. Stress and Disease 1. Can lead to gastritis, ulcerative colitis, irritable bowel, peptic ulcers, hypertension, asthma, rheumatoid arthritis, migraines, anxiety, and depression 2. Increases the risk of chronic diseases and premature death