What is the function of the hormone ACTH?

The hormone ACTH, or adrenocorticotropic hormone, plays a critical role in the body's response to stress by stimulating the adrenal glands, specifically the production of cortisol and other adrenal hormones. When ACTH is released from the pituitary gland in response to biological stressors, it prompts the adrenal cortex to generate steroid hormones which are vital for various physiological functions, including metabolism, immune response, and maintaining blood sugar levels.

This function is essential for the body's adaptation to stress and helps ensure that energy is available when needed. Cortisol, the primary hormone released in this pathway, has widespread effects on various systems in the body, thus making ACTH's role pivotal in maintaining homeostasis, especially during periods of physiological stress.

The other options relate to different hormones or systems that are not directly influenced by ACTH. For instance, sleep regulation is primarily managed by hormones like melatonin, while thyroid hormone secretion is stimulated by thyroid-stimulating hormone (TSH). Blood pressure regulation may involve various hormones, such as adrenaline and aldosterone, but ACTH itself does not have a direct impact on this process.