What is the Origin of Hypothalamic Pituitary Adrenal Response?

The concept of the HPA axis emerged from the foundational work of Hans Selye on the General Adaptation Syndrome in the mid-20th century, which established the biological basis of the stress response. The full delineation of the axis involves the sequential discovery of the relevant hormones, including Corticotropin-Releasing Hormone (CRH), ACTH, and Cortisol, and the mapping of their precise feedback loops.

What is the Mechanism of Hypothalamic Pituitary Adrenal Response?

The response begins when the hypothalamus releases CRH, which stimulates the anterior pituitary gland to secrete Adrenocorticotropic Hormone (ACTH). ACTH then travels via the bloodstream to the adrenal cortex, prompting the release of the glucocorticoid cortisol. Cortisol mobilizes energy reserves and modulates the immune system to cope with the stressor. Crucially, cortisol then acts back on the hypothalamus and pituitary in a negative feedback loop to suppress further CRH and ACTH release, restoring systemic balance.

Hypothalamic Pituitary Adrenal Response ∞ Area

Hypothalamic Pituitary Adrenal Response

Meaning

The Hypothalamic Pituitary Adrenal Response, commonly known as the HPA axis, is the central neuroendocrine system that governs the body’s reaction to stress and regulates numerous homeostatic processes. This intricate, interconnected network of glands coordinates the release of stress hormones to facilitate adaptation and survival. Its dynamic activation is a necessary physiological response to both physical and psychological stressors.