Which feature is characteristic of an electrical synapse but NOT of a typical chemical synapse?
- A Transmission delay of about 0.5 ms per synapse
- B Requirement for calcium influx into the presynaptic element
- C Current flow through connexon channels allowing near-instantaneous, often bidirectional signaling ✓
- D Ability to amplify a signal through quantal release of transmitter
Correct answer: C. Current flow through connexon channels allowing near-instantaneous, often bidirectional signaling
Explanation
Electrical synapses are gap junctions formed by connexons that allow direct ion current flow between cells, giving essentially zero delay and frequently bidirectional passage of signal. Chemical synapses show a synaptic delay of roughly 0.5 ms and are inherently unidirectional. The distractor A describes the hallmark delay of chemical transmission, and B is required for vesicle release, both of which are absent at electrical synapses.
Reference: Ganong's Review of Medical Physiology, 27th ed.
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