A chemical synapse is characterized by...

• A. Direct ion flow between cells
• B. Electrical coupling via gap junctions
• C. Uses neurotransmitters
• D. Myelin sheath formation

Answer: (C)

Chemical communication at the synapse relies on neurotransmitters released from the presynaptic terminal into the synaptic cleft, which then bind to receptors on the postsynaptic membrane to generate a response in the next cell. This chemical signaling converts an electrical signal into a chemical one and back, with the release of transmitter triggered by calcium influx when a presynaptic action potential arrives. The transmission is typically unidirectional and can be excitatory or inhibitory depending on the receptors and ion channels involved. The other options describe electrical coupling through gap junctions or processes like myelination, which speed conduction but do not define how a chemical synapse transmits signals. So, using neurotransmitters is the defining feature.