Synapse
A connection lets one cell influence the activity of another cell.
Definition
A synapse is a specialized functional junction through which a neuron communicates with another neuron or a target cell.
How to understand it
At a chemical synapse, the sending terminal releases neurotransmitter into a small cleft, and receptors on the receiving cell respond. The receiving response is not automatically another action potential. It contributes to the cell’s ongoing integration of inputs. A synapse therefore includes the communication machinery on both sides, not simply the empty space between them.
The concept helps separate a connection from the signal carried across it. In an explanation of a circuit, ask where communication occurs, what is released, and how the receiving cell responds. Those questions prevent the common shortcut in which a chemical messenger is treated as if it were the whole connection or an electrical spike simply leaps through open space.
Evidence: (Spielman et al., 2020); (Noba: Neurons, n.d.); (A. C. Miller & Pereda, 2017)
Marking the handoff
Teaching scenario
A student draws two cells and places colored dots between them to represent a chemical message. The teacher asks the student to circle the synapse. The student includes the sending terminal, cleft, and receiving membrane rather than circling one dot. Removing a dot changes the illustrated message; removing the junction changes the possible route of communication in the diagram.
Constructed for learning. This scenario is not a report of an empirical finding or a diagnosis.
Common confusion: Neurotransmitter
A synapse is a junction; a neurotransmitter is a chemical signal used at chemical synapses.
Evidence: (Spielman et al., 2020); (Noba: Neurons, n.d.); (A. C. Miller & Pereda, 2017)
Limits of the concept
- The cleft is part of a chemical synapse, not a complete definition of every synapse.
- Simplified diagrams omit many molecular processes and other kinds of cellular connections.
Evidence: (Spielman et al., 2020); (Noba: Neurons, n.d.); (A. C. Miller & Pereda, 2017)
Textbook connection
Direct coveragePsychology 2e: 3.2 Cells of the Nervous System
Direct chemical-synapse and synaptic-cleft coverage; profile distinguishes the junction from its cleft.
Supplementary concepts may extend beyond this section. The source notes below identify the evidence for those details.
Related concepts
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Sources and inspection notes
Checked October 21, 2026. An inspection date is not a source publication date. Definitions and scenarios on this page are original teaching explanations.
- Miller, A. C., & Pereda, A. E. (2017). The electrical synapse: Molecular complexities at the gap and beyond. Developmental Neurobiology, 77(5), 562–574. https://doi.org/10.1002/dneu.22484Consulted sourceSynapse is broader than the cleft of a chemical junction; electrical synapses are molecularly organized connections.
Abstract inspected in search retrieval on 21 October 2026. Direct PubMed open returned a footer; full article not inspected. Review article, not primary experimental evidence.
- Noba: Neurons. (n.d.). https://nobaproject.com/modules/neuronsCell anatomy, graded inputs, action potentials, and receptor-dependent synaptic signaling; no precise cell counts used.
Opened and inspected on 21 October 2026. Academic teaching synthesis; not a primary experiment.
- Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020). Psychology 2e. OpenStax. https://openstax.org/books/psychology-2e/pages/3-2-cells-of-the-nervous-systemCourse textbook section
Opened actual subsection on 21 October 2026; title and URL verified. Course textbook, not independent primary evidence.