What is a synapse?

• A. A gap between neurons where signal is not transmitted.
• B. A site where action potentials are generated.
• C. A junction that converts an electrical impulse into a chemical signal for inter-neuronal communication.
• D. The site of energy production in a neuron.

Answer: (C)

The main idea is that a synapse is the junction where neurons communicate by turning an electrical signal into a chemical one. When an action potential reaches the presynaptic terminal, it triggers the release of neurotransmitters into the tiny gap between neurons. These chemical messengers diffuse across the gap and bind to receptors on the postsynaptic neuron, converting that chemical signal back into an electrical response in the next neuron. This chemical-to-electrical handoff is what allows inter-neuronal communication and modulation of neural circuits.

That’s why this description fits best: a junction that converts an electrical impulse into a chemical signal for inter-neuronal communication. The other statements don’t capture the key process. A describes a gap where no signal is transmitted, which isn’t true because transmission occurs chemically. B points to a site where action potentials are generated, which is at the axon hillock, not the synapse. D refers to energy production in mitochondria, not the synapse.