Final answer:
The key component in Selye's general adaptation syndrome is the hypothalamic-pituitary-adrenal axis. This system explains how the body responds to stress in three stages - alarm reaction, stage of resistance, and stage of exhaustion, with cortisol playing a significant role in coping with stressors.
Step-by-step explanation:
The body system that plays the greatest role in Selye's general adaptation syndrome is called the hypothalamic-pituitary-adrenal axis. This physiological mechanism is central to how the body responds to stress and involves three pivotal components: the hypothalamus, the pituitary gland, and the adrenal glands.
When a stressor is perceived, the hypothalamus releases corticotropin-releasing factor (CRF), which prompts the pituitary gland to secrete adrenocorticotropic hormone (ACTH). ACTH then signals the adrenal glands to produce cortisol, among other hormones, which facilitates the fight-or-flight response by increasing energy availability and suppressing non-essential processes like the immune response.
Selye's general adaptation syndrome outlines three stages of stress response: the alarm reaction, the stage of resistance, and the stage of exhaustion. These stages reflect an initial acute response, a longer-term adaptation phase, and finally a depletion of the body's resources if the stress is prolonged or repeated. Sustained high levels of cortisol can lead to adverse health outcomes such as weakened immunity, hypertension, and coronary artery disease.