What are chemical substances that act like messenger molecules in the body?

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

Answer: (C)

Chemical messengers that coordinate activities throughout the body are hormones. They’re produced by endocrine glands and released into the bloodstream, where they travel to distant target cells. When a hormone binds to its receptors, it triggers specific responses that regulate processes like metabolism, growth, and reproduction. This body-wide signaling distinguishes hormones from other signaling molecules. Antibodies are immune proteins, not signaling messengers. Enzymes are catalysts for chemical reactions. Neurotransmitters are signaling molecules in the nervous system that act locally across synapses and do so quickly, not traveling through the blood to distant organs. Because hormones travel through the bloodstream to affect many parts of the body and often produce longer-lasting effects, they best fit the description of chemical substances that act like messenger molecules in the body.