What are hormones?

Hormones are best defined as chemical messengers that travel through the bloodstream. They are produced by glands in the endocrine system and released directly into the circulatory system, where they play crucial roles in regulating various physiological processes including growth, metabolism, and mood. Hormones communicate with specific target cells and organs, influencing functions such as metabolism, immune response, and reproductive processes.

This definition highlights the unique nature of hormones as chemical signals distinct from other forms of signaling within the body, such as those that occur in the nervous system. For instance, while neurotransmitters facilitate communication between neurons through synaptic transmission, hormones operate over greater distances in the body, facilitating slower but longer-lasting effects compared to the rapid response associated with electrical signals in neurons.

The other options present different forms of biological signaling. The first option inaccurately describes hormones by suggesting they are produced by hormones themselves, which is a misunderstanding of their nature. The second option refers to the signaling mechanisms of the nervous system, specifically between neurons, which relies on neurotransmitters rather than hormones. The final option describes electrical signals, a feature of neuronal communication, emphasizing the differences in how the neural and endocrine systems operate.