Chapter 5 Flashcards

acetylcholine
Neurotransmitter at motor neuron synapses, in autonomic ganglia, and in a variety of central synapses. Binds to two types of acetylcholine receptors (AChRs), either ligand-gated ion channels (nicotinic receptors) and G-protein-coupled receptors (muscarinic receptors).
clathrin
The most important protein for endocytotic budding of vesicles from the plasma membrane; its three-pronged "triskelia" attach to the vesicular membrane to be retrieved.
co-transmitters
Two or more types of neurotransmitters within a single synapse; may be packaged into separate populations of synaptic vesicles or co-localized within the same synaptic vesicles.
connexons
Precisely aligned, paired transmembrane channels that form gap junctions between cells. They are formed from connexins, members of a specialized family of channel proteins.
end plate current (EPC)
A macroscopic postsynaptic current resulting from the summed opening of many ion channels; produced by neurotransmitter release and binding at the motor end plate.
end plate potential (EPP)
Depolarization of the membrane potential of skeletal muscle fiber, caused by the action of the transmitter acetylcholine at the neuromuscular synapse.
end plate
The complex postsynaptic specialization at the site of nerve contact on skeletal muscle fibers.
excitatory postsynaptic potential (EPSP)
Neurotransmitter-induced postsynaptic potential change that depolarizes the cell, and hence increases the likelihood of initiating an action potential.
G-protein-coupled receptors
A large family of neurotransmitter or hormone receptors, characterized by seven transmembrane domains; the binding of these receptors by agonists leads to the activation of intracellular G-proteins.
G-proteins
Proteins that are activated by exchanging bound GDP for bound GTP (and thus also known as GTP-binding proteins).
gap junction
A specialized intercellular contact formed by channels that directly connect the cytoplasm of two cells.
inhibitory postsynaptic potential (IPSP)
Neurotransmitter-induced postsynaptic potential change that tends to decrease the likelihood of a postsynaptic action potential.
ionotropic receptors
Receptors in which the ligand binding site is an integral part of the receptor molecule.
ligand-gated ion channels
Ion channels that respond to chemical signals rather than to the changes in membrane potential generated by ionic gradients. The term covers a large group of neurotransmitter receptors that combine receptor and ion channel functions into a single molecule.
miniature end plate potential (MEPP)
Small, spontaneous depolarization of the membrane potential of skeletal muscle cells, caused by the release of a single quantum of acetylcholine.
metabotropic receptors
Receptors that are indirectly activated by the action of neurotransmitters or other extracellular signals, typically through the aegis of G-protein activation. Also called G-protein-coupled receptors.
neurotransmitter
Substance released by synaptic terminals for the purpose of transmitting information from one cell (the presynaptic cell) to another (the postsynaptic cell).
postsynaptic
Referring to the component of a synapse specialized for transmitter reception; downstream at a synapse.
postsynaptic current (PSC)
The current produced in a postsynaptic neuron by the binding of neurotransmitter released from a presynaptic neuron.
postsynaptic potential (PSP)
The potential change produced in a postsynaptic neuron by the binding of neurotransmitter released from a presynaptic neuron.
presynaptic
Referring to the component of a synapse specialized for transmitter release; upstream at a synapse.
reversal potential
Membrane potential of a postsynaptic neuron (or other target cell) at which the action of a given neurotransmitter causes no net current flow.
summation
The addition in space and time of sequential synaptic potentials to generate a larger than normal postsynaptic response.
synaptic cleft
The space that separates pre- and postsynaptic neurons at chemical synapses.
synaptic vesicles
Spherical, membrane-bound organelles in presynaptic terminals that store neurotransmitter molecules.
synaptic vesicle cycling
Sequence of budding and fusion reactions that occurs in presynaptic terminals to maintain the supply of synaptic vesicles.
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