The normal stress response.
The Normal Stress response
The hypothalamic-pituitary-adrenal (HPA) axis is the body's central stress response system, it is the pathway that controls reactions to stress and regulates many body processes, including digestion, the immune system, mood, sexuality, and energy storage.
The Function of the HPA Axis
When the brain perceives a threat the chain reaction initiated is like a 4 man sprint relay team:
The Hypothalamus (the brain’s control center) starts with the baton in the form of CRH: the hypothalamus releases corticotropin-releasing hormone (CRH).
The Pituitary Gland receives the baton: The pituitary gland takes CRH baton sent from the hypothalamus and takes off with the release adrenocorticotropic hormone (ACTH).
The Adrenal Glands receive the baton: The adrenal glands take the ACTH baton traveling through the bloodstream and takes off with the release of cortisol, the primary stress hormone.
Cortisol floods the body with energy for a "fight or flight" response—increasing blood sugar, suppressing non-essential functions like the immune and digestive systems, and narrowing arteries.
Once the stressor has passed, cortisol levels drop, and the body returns to a state of balance (homeostasis).
This is a process regulated by a negative feedback loop where high cortisol levels signal the hypothalamus and pituitary to stop producing their stimulating hormones. This is what should happen if you are experiencing normal stress responses. Next up, what happens when you are in a state of chronic stress.
