How do hormones differ from neurotransmitters?

Hormones are distinct from neurotransmitters primarily in their mode of transmission and range of action. Hormones are secreted directly into the bloodstream, allowing them to travel throughout the body to reach various target organs and tissues that may be located far from their site of release. This systemic action gives hormones the ability to influence numerous physiological processes, such as metabolism, growth, and mood regulation.

In contrast, neurotransmitters are chemicals that transmit signals across a synapse between neurons, typically acting locally. They are released by neurons and quickly bind to receptors on nearby target cells to elicit immediate responses. This localized action is fundamental to the rapid signaling needed for functions such as muscle contractions and reflexes.

The other options reflect misunderstandings about the functions and operating ranges of hormones and neurotransmitters. Hormones can act on distant targets, and they are not restricted to the brain—many hormonal activities occur throughout the body. Additionally, neurotransmitters play a critical role in muscle movement and other neuronal communication, which is separate from the broader and longer-lasting effects of hormones. Understanding these differences is crucial for grasping how the endocrine and nervous systems operate within biological frameworks.