Final answer:
The fight-or-flight response begins with the release of CRH from the hypothalamus, followed by the release of ACTH and ADH from the pituitary, which in turn stimulate the adrenal glands to release additional stress hormones such as cortisol and aldosterone, and ADH acts on the kidneys. Endorphins and TSH are also part of this response; endorphins for pain and stress relief, and TSH to increase metabolism for energy production.
Step-by-step explanation:
During the fight-or-flight response, a sequence of neuroendocrine events is triggered to prepare the body for a rapid reaction to a perceived threat. Here's the order in which these events occur:
- Corticotropin-releasing hormone (CRH) is released from the hypothalamus.
- CRH stimulates the pituitary gland to release adrenocorticotropic hormone (ACTH) and antidiuretic hormone (ADH).
- ACTH stimulates the adrenal glands to release glucocorticoids (cortisol) and mineralocorticoids (aldosterone).
- ADH stimulates the renal tubules to reabsorb water, helping to conserve fluid and maintain blood pressure.
- Endorphins, which produce a sense of well-being and reduce pain, are released by the hypothalamus and posterior pituitary.
- Thyroid-stimulating hormone (TSH) is released by the pituitary gland to increase cellular metabolism efficiency and aid in energy production.
This response includes the quick release of adrenaline and noradrenaline from the adrenal medulla, under the stimulation of the sympathetic nervous system, which leads to increased heart rate and blood pressure, among other effects. The HPA (hypothalamic-pituitary-adrenal) axis then contributes to long-term stress management through the release of hormones like cortisol.