Generally, I appreciate the eustress that I regularly experience; however, when a stressor mainly causes me distress, I often experience frustrating bodily reactions such as an increased heart rate and constipation.
I now know that this happened due to my body's homeostatic mechanism responding to a strong disturbance in my emotions and mind. The body's response starts at the hypothalamus which initiates the fight-or-flight response through nerve impulses and onto the sympathetic division of the autonomic nervous system as well as to the adrenal medulla. This prompts the body to prepare and mobilize the body's resources for immediate physical activity.
The nerve impulses induce the sympathetic nervous system to act on the visceral effectors. Some of the stress responses generated by visceral effectors include increased heart rate, vasoconstriction, and a decrease in digestive activities.
In the endocrine system, Corticotropin-releasing Hormone (CRH) stimulates the anterior pituitary gland to secrete Adrenocorticotropic hormone (ACTH) which acts upon the adrenal cortex so that cortisol release may be increased because cortisol is necessary for the liver to execute lipolysis, protein catabolism, and blood vessel sensitization. Growth hormone-releasing hormone (GHRH) also stimulates the anterior pituitary gland to secrete Human growth hormone (hGH) which triggers the liver to participate in lipolysis and glycogenesis as well. Lastly, Thyrotropin-releasing hormone (TRH) from the hypothalamus stimulates the anterior pituitary gland to secrete Thyroid-stimulating hormone (TSH) that makes the thyroid respond to stress by increasing the use of glucose to produce ATP.
Reference/s:
Tortora, G. J., & Derrickson, B. (2013). Principles of anatomy and physiology (14th ed.). Wiley Custom Learning Solutions.