Which of the following best describes the primary difference between a hormone and a neurotransmitter?

• A. Hormones transmit signals electrically, while neurotransmitters transmit signals chemically.
• B. Neurotransmitters are always proteins, while hormones are always lipids.
• C. Hormones are chemical messengers released into the bloodstream, while neurotransmitters are released at synapses between neurons.
• D. Hormones only act within the nervous system, while neurotransmitters act throughout the entire body.

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by understanding the definitions of hormones and neurotransmitters. Hormones are chemical messengers secreted by endocrine glands into the bloodstream, where they travel to target tissues or organs to elicit a response. Neurotransmitters, on the other hand, are chemical messengers released by neurons at synapses to transmit signals to other neurons, muscles, or glands.
2. Step 2: Compare the mechanisms of action. Hormones are distributed throughout the body via the circulatory system, allowing them to affect distant target cells. Neurotransmitters act locally at synapses, where they bind to receptors on adjacent cells to propagate or inhibit electrical signals.
3. Step 3: Analyze the scope of their effects. Hormones typically have a broader and longer-lasting impact on physiological processes, such as growth, metabolism, and reproduction. Neurotransmitters generally have a faster and more localized effect, primarily influencing nervous system functions like reflexes and cognition.
4. Step 4: Evaluate the statement options provided in the problem. Eliminate incorrect choices by cross-referencing them with the definitions and mechanisms of hormones and neurotransmitters. For example, hormones do not transmit signals electrically, and neurotransmitters are not exclusively proteins.
5. Step 5: Identify the correct answer based on the comparison. The statement 'Hormones are chemical messengers released into the bloodstream, while neurotransmitters are released at synapses between neurons' accurately describes the primary difference between the two.