NROC69H3 Lecture Notes - Lecture 2: Axon Terminal, Nicotinic Acetylcholine Receptor, Threshold Potential
Document Summary
Chemical neurotransmission recap: dominant form of neuron to neuron transmission of information. Arrive of an action potential at the presynaptic terminal triggers a cascade of cellular events that result in the release of a neurochemical substance (neurotransmitter) across the synaptic cleft. Neurotransmitter release: the neurotransmitter binds to receptors embedded in the postsynaptic membrane to bring about a change in the electrical property of the postsynaptic cell (in the form of graded potentials). Mechanism of neurotransmitter release: opening of voltage gated ca2+ channels in the presynaptic terminal. Allows the influx of ca2+ ions to cause fusion of neurotransmitter filled vesicles with the presynaptic membrane. The vesicles then release the neurotransmitter into the synaptic cleft, which in turn diffuses across to bind to postsynaptic receptors. Two types of postsynaptic receptors: 1) ionotropic, 2) metabotropic. Ionotropic postsynaptic receptors: transmembrane molecules that can "open" or "close" a channel that would allow smaller particles (ions) to travel in and out of the cell.