PHSI2005 Study Guide - Midterm Guide: Inhibitory Postsynaptic Potential, Electrical Synapse, Second Messenger System
15 Jan 2019
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Refer to the changes that occur in basic electrical properties and how these, in turn, affect action potential propagation. (cid:120) In demyelinated fibres (e. g. due to damage by oligodendrocytes; in multiple sclerosis) Increases permeability of membrane to ions in the demyelinated internode regions (cid:131) reduced membrane electrical resistance leads to loss of amplitude of signal. Increased membrane capacitance in the denervated internode regions (cid:131) How would you expect this to affect the time-course of depolarising synaptic potentials arising from synapses on the dendrites? (cid:120) It would be slow due to a higher axoplasmic resistance. Local circuit currents synaptic integration: explain the difference between an electrical synapse and a chemical synapse. Neurotransmitter binding with its receptor on the postsynaptic cell either initiates (1) an electrical response, or (2) a second messenger pathway (1) electrical response. Fast synaptic transmission involves neurotransmitters which bind to and open a specific type of ligand-gated ion channel.
