Final answer:
Stress invokes a physiological response involving the sympathetic nervous system and the HPA axis, affecting the secretion of several hormones. Stress increases epinephrine, inhibiting insulin and promoting glucagon release. Chronically, it triggers the CRH-ACTH-Cortisol pathway, elevating cortisol to provide energy and suppress the immune system.
Step-by-step explanation:
How Stress Affects Hormone Secretion
When we experience stress, the body's physiological response involves several systems, notably the sympathetic nervous system and the hypothalamic-pituitary-adrenal (HPA) axis. Initially, the sympathetic nervous system triggers the release of epinephrine and norepinephrine, producing the fight-or-flight response. This leads to increased heart rate and respiration. Conversely, chronic stress can lead to prolonged secretion of cortisol, detrimental to immune system function.
In the context of hormone secretion, stress affects insulin in that epinephrine inhibits insulin secretion by decreasing cAMP levels. This is likely an adaptive response to stress, where the body aims to keep glucose in circulation for immediate energy use, rather than storing it. Glucagon, meanwhile, is stimulated, enhancing glucose production and raising blood sugar levels.
The CRH-ACTH-Cortisol pathway is a critical long-term stress response. Stressors activate the hypothalamus to release CRH, which in turn stimulates ACTH release from the pituitary gland. ACTH prompts the adrenal glands to secrete cortisol. This hormone helps mobilize stored nutrients, thereby maintaining energy supply and promoting glucose synthesis, at the cost of suppressing the immune system.
Finally, long-term stress response modifies bodily functions via corticosteroids released by the adrenal cortex. This includes cortisol and aldosterone, which raise heart rate, breathing rate, muscle contractions, blood pressure, and glucose levels as part of the long-term stress response. Here, cortisol promotes the catabolism of stored nutrients and inhibits tissue building, favoring the maintenance of fuel supplies.