Which feature correctly characterizes an electrical synapse as opposed to a chemical synapse?
- A Current flows through gap junction connexons with essentially no synaptic delay, and transmission is often bidirectional ✓
- B Transmission shows marked synaptic delay of about 0.5 ms
- C It amplifies weak presynaptic signals like a chemical synapse does
- D Its channels are gated by presynaptic calcium influx
Correct answer: A. Current flows through gap junction connexons with essentially no synaptic delay, and transmission is often bidirectional
Explanation
Electrical synapses are formed by connexons forming gap junctions between the two membranes. Ions pass directly from one cell to the other, giving a synaptic delay close to zero and frequently bidirectional signal flow. They are used where synchrony matters, such as cardiac muscle, smooth muscle, and certain brainstem and retinal circuits. Chemical synapses show a delay of about 0.5 ms and are unidirectional, and their vesicle release depends on presynaptic calcium entry, which does not apply here.
Reference: Ganong's Review of Medical Physiology, 26th ed.
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