Activation of the hypothalamic-pituitary-adrenal (HPA) axis results in the secretion of:

Correct option is A

The hypothalamic-pituitary-adrenal (HPA) axis is a central stress response system that regulates hormonal responses to stress.

Steps in HPA Axis Activation:
1.Stress or threat perception activates the hypothalamus, which releases Corticotropin-Releasing Hormone (CRH).
2.CRH stimulates the pituitary gland to release Adrenocorticotropic Hormone (ACTH).
3.ACTH travels through the bloodstream to the adrenal cortex, stimulating the release of cortisol.
4.Cortisol, a glucocorticoid hormone, helps the body manage stress by:
-Increasing blood sugar levels for energy.
-Suppressing immune function to prevent excessive inflammation.
-Regulating metabolism and blood pressure.
-Enhancing alertness and focus.

Information Booster:

Suppression of Immune Cell Activity
-Cortisol inhibits the production and activity of lymphocytes (T-cells & B-cells), reducing the body's ability to fight infections.
-Natural Killer (NK) cells, which help destroy viruses and cancerous cells, are suppressed.

Reduction in Pro-inflammatory Cytokines
-Cortisol decreases the release of pro-inflammatory cytokines like IL-1, IL-6, and TNF-α, weakening immune responses.
-While beneficial in short-term stress (to prevent excessive inflammation), long-term suppression increases infection risk.

Thymus Gland Shrinkage (Thymic Atrophy)
-Chronic stress leads to a reduction in thymus size, decreasing T-cell maturation and impairing immune responses.

Decreased Antibody Production
-Stress reduces Immunoglobulin A (IgA), which plays a role in mucosal immunity, making individuals more prone to respiratory and digestive infections.

Additional Information:

Option 2: Catecholamines –
Catecholamines (epinephrine, norepinephrine, and dopamine) are released by the sympathetic nervous system and adrenal medulla

Option 3: Norepinephrine –
Norepinephrine is a catecholamine involved in the fight-or-flight response, secreted by the adrenal medulla and sympathetic nervous system

Option 4: Pepsin – Incorrect
Pepsin is an enzyme that aids in protein digestion in the stomach