A synapse in which electrical current flows directly from one cell to another via a gap junction.
A synapse in which presynaptic activity stimulates the release of neurotransmitter, which activates receptors in the postsynaptic membrane.
A specialized junction where a narrow gap between two cells is spanned by protein channels (connexons) that allow ions to pass directly from one cell to another.
postsynaptic potential (PSP)
A change in the postsynaptic membrane potential by the presynaptic action of an electrical synapse, or a synaptically released neurotransmitter.
A spherical membrane-enclosed vesicle about 100nm in diameter containing peptides intended for secretion by exocytosis; also called dense-core vesicle
A dense accumulation of protein adjacent to and within the membrane on either side of a synaptic cleft.
A postsynaptic membrane differentiation that is the site of neurotransmitter receptors.
A chemical synapse between a spinal motor neuron axon and a skeletal muscle fiber.
gamma-aminobutyric acid (GABA)
An amino acid synthesized from glutamate; the major inhibitory neurotransmitter in the central nervous system.
An amino acid; an inhibitory neurotransmitter at some locations in the central nervous system.
An amine that serves as a neurotransmitter at many synapses in the peripheral and central nervous systems, including the neuromuscular junction.
A membrane protein that transports neurotransmitters, or their precursors, across membranes to concentrate them in either presynaptic cytosol or synaptic vesicles.
voltage-gated calcium channel
A membrane protein forming a pore that is permeable to calcium ions and gated by depolarization of the membrane.
The process whereby material is released from an intracellular vesicle into the extracellular space by fusion of the vesicle membrane with the cell membrane.
The process by which a bit of the cell membrane is pinched off, internalized, and converted to an intracellular vesicle.
transmitter-gated ion channel
A membrane protein forming a pore that is permeable to ions and gated by neurotransmitter.
excitatory postsynaptic potential (EPSP)
Depolarization of the postsynaptic membrane potential by the action of a synaptically released neurotransmitter.
inhibitory postsynaptic potential (IPSP)
A change in the postsynaptic membrane potential by the action of a synaptically released neurotransmitter, making the postsynaptic neuron less likely to fire action potentials.
A membrane protein that activates G-proteins when it binds neurotransmitter.
A membrane-enclosed protein that binds guanosine triphosphate (GTP) when activated by a membrane receptor. Active G-proteins can stimulate or inhibit other membrane-enclosed proteins.
A multistep process that couples activation of a neurotransmitter receptor activation of intracellular enzymes.
A G-protein-coupled receptor whose primary action is to stimulate an intracellular biochemical response.
A receptor in the membrane of a presynaptic axon terminal that is sensitive to the neurotransmitter released by that terminal.
nicotinic ACh receptor
A class of acetylcholine-gated ion channel found in various locations, notably the neuromuscular junction.
The process by which multiple EPSPs and/or IPSPs combine within one postsynaptic neuron, in some cases triggering one or more action potentials.
miniature postsynaptic potential
A change in postsynaptic membrane potential caused by the action of neurotransmitter released from a single synaptic vesicle.
A method of determining how many vesicles release neurotransmitter during normal synaptic transmission.
A simple form of synaptic integration whereby excitatory postsynaptic potentials combine to produce a larger postsynaptic depolarization.
The combining of excitatory postsynaptic potentials generated at more than one synapse on the same cell.
The combining of excitatory postsynaptic potentials generated in rapid succession at the same synapse.
A parameter used to describe how far changes in membrane potential can passively spread down a cable such as an axon or a dendrite, represented by the symbol lambda. The length constant lambda is the distance at which the depolarization falls to 37% of its original value; it depends on the ratio of membrane resistance to internal resistance.
The resistance to electrical current flows longitudinally down a cable or neurite, represented by the symbol ri.
The resistance to electrical current flow across a membrane; represented by the symbol rm.
A form of synaptic inhibition in which the main effect is to reduce membrane resistance, thereby shunting depolarization current generated at excitatory synapses.
A term used to describe the actions of neurotransmitters that do no directly evoke postsynaptic potentials but modify the cellular response to excitatory postsynaptic potentials and inhibitory postsynaptic potentials generated by other synapses.
A catecholamine neurotransmitter synthesized from dopamine; also called noradrenaline.
An enzyme that catalyzes the conversion of adenosine triphosphate to cyclic adenosine monophosphate (cAMP), a second messenger.
cyclic adenosine monophosphate (cAMP)
A second messenger formed from adenosine triphosphate by the action of the enzyme adenylyl cyclase.
A class of enzyme that phosphorylates proteins, a reaction that changes the conformation of the protein and its biological activity.