Which property distinguishes an electrical synapse from a chemical synapse?
- A Electrical synapses allow direct current flow between cells through connexons with essentially no delay ✓
- B Electrical synapses transmit in one direction only
- C Transmission shows a delay of about 0.5 ms at the electrical synapse
- D Electrical synapses amplify signals by releasing transmitter from both sides
Correct answer: A. Electrical synapses allow direct current flow between cells through connexons with essentially no delay
Explanation
Electrical synapses are gap junctions formed by connexons connecting the cytoplasms of two neurons, allowing ions and small molecules to pass directly. Transmission is nearly instantaneous, bidirectional, and not dependent on vesicle release. Chemical synapses show a 0.5 ms synaptic delay and are typically unidirectional. Electrical synapses are important where speed or synchronization matters, such as cardiac myocytes, smooth muscle syncytia, and some brainstem circuits mediating escape reflexes.
Reference: Ganong's Review of Medical Physiology, 26th ed.
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