Which term describes the body's chemical messengers that travel through the bloodstream to regulate distant organs?

• A. Neurons
• B. Enzymes
• C. Hormones
• D. Antibodies

Answer: (C)

Hormones are the body's chemical messengers that travel through the bloodstream to regulate distant organs. They are released by endocrine glands, enter the blood, and bind to specific receptors on target cells somewhere else in the body. This binding triggers changes in metabolism, growth, development, or function, coordinating processes across multiple tissues. The system’s ability to affect distant organs explains why hormones influence wide-ranging activities like blood sugar control, stress responses, and growth.

Neurons, by contrast, use electrical signals and neurotransmitters to communicate quickly across synapses, usually over short distances and within the nervous system. Enzymes are catalysts that speed up chemical reactions, not signaling messengers that travel through the blood to regulate organs. Antibodies are immune proteins that identify and help neutralize pathogens, with a defensive role rather than coordinating organ-wide regulation.