ADP (adenosine diphosphate) is not a hormone. It's a nucleotide that plays a crucial role in cellular energy metabolism and is closely related to ATP (adenosine triphosphate). Hormones are chemical messengers produced by glands and transported via the bloodstream to target organs to regulate various physiological processes.
While ADP is involved in numerous cellular processes, it doesn't act as a hormone. It's a crucial component of the energy cycle within cells, being converted to ATP for energy usage and back again during cellular respiration.
