| receptors, presynaptic | Neurotransmitter receptors located on or near presynaptic terminals or varicosities. Presynaptic receptors which bind transmitter molecules released by the terminal itself are termed autoreceptors. (12 Dec 1998) |
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| presynaptic | <anatomy, physiology> Situated proximal to a synapse or occurring before the synapse is crossed. (05 Mar 1998) |
| presynaptic cell | <physiology> In a chemical synapse, the cell that releases neurotransmitter that will stimulate the postsynaptic cell. <neurology> In an electrically synapsed system, the cell that has the first action potential, but since synapses are rectifying, one of the two cells involved is always presynaptic. (05 Mar 1998) |
| presynaptic membrane | That part of the plasma membrane of an axon terminal that faces the plasma membrane of the neuron or muscle fibre with which the axon terminal establishes a synaptic junction; many synaptic junctions exhibit structural presynaptic characteristics, such as conical, electron-dense internal protrusions, that distinguish it from the remainder of the axon's plasma membrane. See: synapse. (05 Mar 2000) |
| presynaptic receptor | <physiology> Receptors located on presynaptic terminals at synapses. (05 Mar 1998) |
| presynaptic terminals | The distal terminations of axons which are specialised for the release of neurotransmitters. Also included are varicosities along the course of axons which have similar specializations and also release transmitters. Presynaptic terminals in both the central and peripheral nervous systems are included. (12 Dec 1998) |