Synapse

A synapse is the junction between two nerve cells (neurons), or between a neuron and another target cell (such as a muscle cell), where nerve impulses are transmitted from one cell to the next. In a chemical synapse, the signal is carried by neurotransmitters released from the presynaptic neuron across a tiny gap (the synaptic cleft) to the postsynaptic cell.

• Synapse structure: the presynaptic cell's axon terminal releases neurotransmitters into the synaptic cleft, which bind to receptors on the postsynaptic cell, triggering a response.
• Not all synapses are chemical; some are <u>electrical synapses</u> where cells are connected by gap junctions, allowing direct ionic current flow for faster signal transmission.
• Example: The neuromuscular junction is a specialized synapse where a motor neuron communicates with a muscle fiber using the neurotransmitter acetylcholine.

• Clue in questions: "gap between neurons where communication occurs" or "junction where neurotransmitters are released" points to a <u>synapse</u>.
• Term trap: Do not confuse synapse (neural junction) with synapsis (pairing of chromosomes in meiosis). They sound similar but refer to entirely different processes.