Which hormone stimulates the adrenal cortex?

The hormone that stimulates the adrenal cortex is ACTH, or adrenocorticotropic hormone. This hormone is produced and released by the anterior pituitary gland in response to corticotropin-releasing hormone (CRH) from the hypothalamus. Once released into the bloodstream, ACTH specifically targets the adrenal cortex, where it promotes the secretion of glucocorticoids, primarily cortisol.

Cortisol plays crucial roles in various bodily functions, including the regulation of metabolism, response to stress, and immune response. By stimulating the adrenal cortex, ACTH is integral in maintaining homeostasis, especially during stress.

In this context, while other hormones like ADH (antidiuretic hormone), cortisol itself, and thyroxine (a thyroid hormone) have distinct functions, they do not have a direct stimulating effect on the adrenal cortex like ACTH does. ADH primarily regulates water balance in the body, cortisol is a product of the adrenal cortex's activity, and thyroxine primarily affects metabolic rate. Thus, ACTH is accurately identified as the hormone responsible for stimulating the adrenal cortex.