The endocrine system works synergistically with other body systems, such as the nervous system.
Under stressful situations, our bodies have an automatic, unconscious response. Depending on the level of stress, the response could include perspiration, dilation of pupils, increased blood pressure, increased heart rate, and increased respiration to name a few. Following is a brief explanation of our body's response to stress.
When a threat is present, the hypothalamus activates two pathways, the sympathomedullary pathway (SAM) for short-term/fast-acting responses and the hypothalamic-pituitary-adrenal (HPA) system for long-term/slow-acting responses. Through the SAM pathway, epinephrine is released from the adrenal medulla. In the HPA pathway, the hypothalamus releases a cortisol-releasing hormone (CRH) to the pituitary. The pituitary releases ACTH into circulation to the adrenal gland. ACTH triggers the adrenal cortex to release glucocorticoids (cortisol) and mineralocorticoids (aldosterone). Cortisol causes extra glucose to be released into the bloodstream to fuel muscle cells as they expend extra energy. The extra glucose is from liver storage, fatty acid catabolism, and gluconeogenesis.
Once the threat is gone, the parasympathetic branch of the autonomic nervous system is activated, which helps shut down the hypothalamus and stop epinephrine and cortisol production. Since cortisol is slow-acting, long-term effects of cortisol still take place after the hormone is no longer being made.
The endocrine and immune systems are continually in flux to create equilibrium. Cortisol has detrimental effects if prolonged like immunosuppressive effects and muscle breakdown as gluconeogenesis breaks down protein from muscle.
