What is the main function of hormones in relation to their signaling mechanism?

Hormones play a crucial role in the regulation of various physiological processes through their signaling mechanisms. The correct answer highlights that hormones can act over long distances, typical of endocrine signaling, where hormones are released into the bloodstream and affect distant target organs or tissues. This long-range communication allows for coordinated responses throughout the body, such as during stress or metabolic changes.

Additionally, hormones can also function locally through paracrine and autocrine signaling. In paracrine signaling, hormones affect nearby cells within the same tissue, while in autocrine signaling, hormones act on the same cell that produces them. This versatility in signaling distances—long and short—enables hormones to regulate complex processes effectively, from growth and metabolism to mood and immune responses.

In contrast, the other options describe functions that do not accurately convey the primary role of hormones in signaling. While structural support, ion transport, and protein synthesis are all essential cellular functions, they are not the main functions of hormones, which are primarily involved in signaling and regulatory processes within the body.