How are cortisol levels regulated in the body?

Cortisol levels are primarily regulated by a negative feedback mechanism that involves the hypothalamus and pituitary gland. This process begins in response to stress or low blood glucose levels, triggering the hypothalamus to release corticotropin-releasing hormone (CRH). CRH then stimulates the anterior pituitary gland to secrete adrenocorticotropic hormone (ACTH). ACTH travels through the bloodstream to the adrenal glands, where it prompts the secretion of cortisol.

Once cortisol is released, it plays essential roles in glucose metabolism, immune response modulation, and stress response. Importantly, elevated cortisol levels signal the hypothalamus and pituitary gland to reduce the production of CRH and ACTH, respectively. This feedback loop helps maintain homeostasis by preventing excessive cortisol production, thereby illustrating the crucial role of negative feedback in endocrine regulation.

In contrast, other mechanisms mentioned either do not accurately describe cortisol regulation or are not involved in this specific process. Positive feedback, voluntary nervous control, and direct secretion without regulation do not account for the sophisticated interplay between these endocrine glands that govern cortisol levels effectively.