Which term describes chemicals released by glands that travel through the bloodstream to affect distant tissues?

Which term describes chemicals released by glands that travel through the bloodstream to affect distant tissues?

• A. Endocrine system
• B. Endorphins
• C. Hormones
• D. Agonist

Answer: (C)

The key idea is endocrine signaling: chemicals released by glands into the bloodstream travel to distant tissues to regulate body processes. Hormones circulate through the blood and bind to receptors on target organs far away from their glands, producing effects that tend to be slower to onset but longer lasting than neural signals. This distinguishes them from neurotransmitters, which act locally at synapses. Endorphins, for example, primarily function as neurotransmitters or neuromodulators in the nervous system, not as circulating signals that reach distant targets. An agonist is any substance that activates a receptor, not specifically a hormone released into the bloodstream.

The key idea is endocrine signaling: chemicals released by glands into the bloodstream travel to distant tissues to regulate body processes. Hormones circulate through the blood and bind to receptors on target organs far away from their glands, producing effects that tend to be slower to onset but longer lasting than neural signals. This distinguishes them from neurotransmitters, which act locally at synapses. Endorphins, for example, primarily function as neurotransmitters or neuromodulators in the nervous system, not as circulating signals that reach distant targets. An agonist is any substance that activates a receptor, not specifically a hormone released into the bloodstream.