Describe how stress influences the immune system through the secretion of hormones.​

A. Brain structures like the hypothalamus produce releasing factors that activate
endocrine glands.
1. Hormones secreted by the endocrine glands reach the adrenal glands and other target organs by traveling to them through the bloodstream.
1. T-cells and B-cells (types of lymphocytes) are equipped with receptors for glucocorticoid stress hormones released by endocrine glands.
B. Activation of the sympathetic nervous system prompts the adrenal glands to release hormones:
1. The adrenal medulla releases epinephrine and norepinephrine.
a. These hormones modulate immunity, apparently via the autonomic nervous system.
2. The adrenal cortex releases cortisol.
a. The hypothalamus in the brain stimulates the pituitary gland to release adrenocorticotropic hormone (ACTH).
b. ACTH stimulates the adrenal cortex to release cortisol.
3. Elevated cortisol levels:
a. are associated with multiple conditions of physiological and psychological distress.
b. exercise an anti-inflammatory effect.
4. Both cortisol and the glucocorticoid hormones tend to inhibit:
a. immune responses
b. phagocytosis
c. macrophage activation.
C. The nervous system thus influences the immune system through:
1. the sympathetic nervous system, or
2.the neuroendocrine response to stress.