Medical Sciences 3999A/B/Y Lecture Notes - Lecture 18: Vasoactive Intestinal Peptide, Glutamine Synthetase, Chemical Synapse
16 Feb 2020
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Document Summary
Neurons communicate with other neurons and with effect cells by synapses. Chemical: conduction of impulses is achieved by release of neurotransmitters (nts) Electrical: involves ion movement between cells via gap junctions, to consequently permit direct spread of electrical current from one cell to another. Gap junctions: visceral smooth muscle, cardiac muscle and in developing embryo. Skeletal muscles require multiple innervations to individual fibres to allow for fine motor control; as such there are no gap junctions to transmit a single impulse. Cardiac muscles however require transmission of an impulse so as to maintain a specific cardiac rhythm in the heart; as such, there require gap junctions. Synaptic vesicles: membrane bound compartments containing nts; ~30-100 nm in diameter; lie close to presynaptic membranes; Neuropeptides (some of these also act like hormones) Based on symmetry of densities on pre- and postsynaptic membranes: Postsynaptic densities appear as more or less discrete patches (resembles patches seen on presynaptic membrane)
