BIOL1040 Lecture Notes - Lecture 2: Excitatory Postsynaptic Potential, Pharmacology, Depolarization
Document Summary
Module 2, lecture 2: action potential conduction and synaptic transmission. Influenced by axon diameter, temperature and degree of myelination: axon diameter. Increased diameter decreased resistance increased speed: squid giant axon 100m/s, temperature. Increased temperature increased speed: degree of myelination, factor that influences conduction speed the most (> axon diameter, conduction speed is affected more by myelination that by axon. Increased myelination increased insulation increased speed diameter: saltatory conduction (myelinated axon, ap jumps between nodes of ranvier, faster than smooth conduction (unmyelinated axons) Junctions through which impulses pass from one neuron (presynaptic) to another (postsynaptic. Electrical synapses: at gap junctions, direct electrical currents between cells, few synapses of this type. Involve neurotransmitter release by presynaptic neuron: majority of synapses are chemical. Direct synaptic transmission: neurotransmitter opens postsynaptic membrane ligand-gated sodium ion channels leads to graded postsynaptic potential, excitatory postsynaptic potential (epsps) depolarisation. Indirect synaptic transmission: neurotransmitter binds to receptor on postsynaptic membrane gpcr activates signal transduction pathway (2nd messenger)
