Adrenocorticotropic Hormone (ACTH)
Adrenocorticotropic Hormone (ACTH) is a hormone secreted by the anterior pituitary gland, a pea-sized structure located at the base of the brain. It plays a crucial role in regulating the body’s response to stress and maintaining proper functioning of the adrenal glands.
Function
ACTH controls the secretion of cortisol, a vital hormone that helps the body respond effectively to stress. It stimulates the adrenal cortex, the outer layer of the adrenal glands, to produce and release cortisol into the bloodstream.
Regulation
The secretion of ACTH is regulated by a negative feedback loop involving the hypothalamus, pituitary gland, and adrenal glands. When cortisol levels in the bloodstream are low, the hypothalamus releases corticotropin-releasing hormone (CRH). CRH then signals the pituitary gland to release ACTH. ACTH, in turn, stimulates the adrenal glands to release cortisol. Once cortisol levels reach an optimal level, it suppresses the release of CRH and ACTH, thereby decreasing cortisol production.
Role in the Body
ACTH and cortisol together play a vital role in several physiological processes, including:
- Regulation of the body’s response to stress, such as by increasing blood pressure and blood sugar levels.
- Maintenance of proper immune system function.
- Regulation of metabolism, including the breakdown of proteins, fats, and carbohydrates.
- Supporting the development and functioning of various organs and tissues, especially during periods of growth and development.
Medical Significance
ACTH levels are measured in medical diagnostics to assess adrenal gland function and diagnose disorders related to their dysfunction. Abnormal ACTH levels can indicate conditions such as Cushing’s syndrome, Addison’s disease, or pituitary tumors.