PHGY 311 Chapter Notes - Chapter 8 & 10: Gap Junction, Ligand-Gated Ion Channel, Second Messenger System
23 Sep 2017
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Document Summary
Synapses: two basic types of synaptic transmission: electrical or chemical. Gap junctions: gap junctions also used in transmission of metabolic signals. Inorganic ions can pass, channel is large and non-selective. Postsynaptic receptors: neurotransmitters can either gate opening if ion channels directly or indirectly, directly = ionotropic, for fast synaptic action, mediate rapid behaviors/reflexes. Indirectly = metabotropic (second messenger: modulate behavior by altering neuron excitability or strength of synapses. Synapses: single sensory neuron usually produces an epsp of < 1mv, far below 10-15mv needed for reaching threshold, excitatory synaptic transmission mediated by ionotropic glutamate receptors, permeable to na+ & k, ns so use erev. Ionotropic receptors: ligand binds and directly opens ion channels i. e. gabaa: metabotropic receptors: g-protein coupled receptors, channels gated by secondary messenger i. e. gabab. Ipsp result from increase in cl conductance (gaba & glycine: glycine channel a little larger in diameter than gabaa so higher conductance, positive driving force generates positive current.
