An introductory text reads, when faced with an emergency, our bodies go through a series of physiological responses that assist us in coping with a stressor. Activation of the fight-or-flight response and hypothalamic-pituitary-adrenal (H P A) system gives us the energy and resources we need to cope with a temporary stressor. Studying these physiological responses, Hans Selye (19 56) found that the sequence follows the same path no matter the stressor. Selye called this sequence the general adaptation syndrome (G A S). He found that when the stressor remains, our bodies can no longer adapt.
Text beside reads, general adaptation syndrome (G A S). In the alarm stage, the short-term responses are activated, giving us the energy to combat a threat. In the resistance stage, resources remain mobilized, and we continue to cope with the stressor. But eventually we enter the exhaustion stage, becoming weak and susceptible to illness, and less able to cope with the stressor. (Selye, 19 56).
A graph plots resistance to stress on the vertical axis against three stages of stress on the horizontal axis. The three stages of stress on the horizontal axis are alarm stage (stress response activated), resistance stage (coping with stressor), and exhaustion stage (reserves diminished). The vertical axis ranges from low to high.
A line starts from the center of the vertical axis and goes horizontally to the right; it is labeled normal level of resistance to stress. The curve starts at the moderate level of alarm stage, slightly rises and goes horizontally to the right to a point labeled stressor, then falls below the normal level, then again rises, intersects the normal level, then rises into the resistance stage, then the curve rises and moves horizontally to the right throughout the resistance stage, then decreases into the exhaustion stage, intersects the normal level, and ends low on the resistance to stress scale.
The alarm stage leads to short-term responses to stress which shows a flow diagram around an illustration of a fire fighter; body parts of the fire fighter are labeled as follows: a small cone-shaped structure located below the thalamus of the brain is labeled hypothalamus. A small gland located between the hypothalamus and pineal gland of the brain is labeled pituitary gland. Two bean-shaped organs located in the upper retroperitoneal region of the abdomen are labeled kidneys. A fatty capsule located on the top of each kidney is labeled adrenal glands. The flow diagram is as follows, stressor branches to fight-or-flight system and hypothalamic-pituitary-adrenal (H P A) system.
Fight-or-flight system: Stressor leads to hypothalamus which activates sympathetic nervous system which sends signal to adrenal medulla (core of adrenal glands) that releases catecholamines such as epinephrine, norepinephrine which further causes efficient management of bodily resources so they are available for emergency action such as increased heart rate, increased respiration, increased blood flow to muscles, digestion slows, and pupils dilate.
Hypothalamic-pituitary-adrenal (H P A) system: Stressors leads to hypothalamus which alerts the pituitary gland which sends a signal to the adrenal cortex (outside layer of adrenal glands) that releases corticosteroids including cortisol which further causes efficient management of bodily resources; immune system activation.
Exhaustion stage leads to prolonged stress. A bar graph plots relative risk of a cold on the vertical axis against duration of stressor in months on the horizontal axis. The horizontal axis ranges from no stressor to more than 24 months and the vertical axis ranges from 0 to 4 in increments of 4. The approximate data from the graph are as follows, no stressor – 1; less than 1 month – 1.6; 1 to 6 months – 2.1; 6 to 24 months – 2.7; more than 24 months – 3.8. A callout below the graph reads, prolonged stress can cause the immune system to break down. As you can see, the risk of becoming sick is directly related to the duration of a stressor. This effect is seen even when the stressor is not traumatic. Data in this study were collected from people reporting on interpersonal conflicts and problems concerning work (Cohen et al., 19 98).