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BIOPSYCH - LEC 3 Synapses turn over within days-morphology...

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LEC 3 (6/29/11) Synapses turn over within days -morphology of layer over time -boutons change over time -bouton form synapse with axon -synapse gets lost, axon again synapse ;system is dynamic Highly specialized for electrical signaling -lipid bilayer: fatty acids -studded with biological machinery(proteins) *electrical activity of given cell is plastic -specialized proteins.. *Action potential K doesn’t exit at resting potential because there is strong electrostatic force pushing the K to remain inside the cell(- attract +) when membrane voltage change, they will open Na Channel to enter the cell. at rest, normally closed -open when the voltage change; action potential: A brief period of depolarization inside becomes positive w.r.t outside V-gated Na channel -membrane potential neg pos neg -at rest, -Na channel (V-gated): closed(not detecting diff in V -passive K channel : -also V-gated K channel: only open when diff in V -depolarized, 1. Na+ : open allow Na to rush in (Na is positive charge-electrostatic force) ; makes neuron even more positive-fast spike of + inside 2. V-gated K : open –allow K to move outside(inside more positive-electrostatic F force K to rush out) 3. Na/K pump will restore the resting potential b/f action potential, all V-gated channels are closed(except for passive) -when axon hillock receive enough, V-Na channel open : allow N to rush in inside becomes positive adjacent Action potential goes only in one direction -absolute refractory period of V-gated channels V-gated K channel- so much Na coming in w.r.t K coming in ; still positive inside *properties of AP -always reaches certain membrane potential - *Synaptic transmission -once AP reach axon terminal -wave of positive -Ca channel detect V change open allow Ca to come in
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-vesicles fuse: neurotransmitters will be released into synaptic cleft -bind to receptors -receptors have specific affinity for specific neurotransmitter -once bound: cause change in shape of receptor—allow some ions to come in (+/-) -ex) some Neurotransmitter usually bind to R that cause neg ions to enter: reduce the likelihood that it will fire AP -what matters are what Receptor it binds to -inhibitory or excitatory -Acetylcholine might bind to inhibitory R or excitatory R *Post-Synaptic Events *Receptor Types -ionotropic R; allow the influx of ions(+/-) -metabotropic R; binding change protein *What happens when the Post-synaptic R are activated? -resting potential-inside is neg r.t. outside(-60mv); polarized -Threshold is V at which Na channels will open(-40mV) -in order to fire AP, need to reach specific threshold. -the post-synaptic neuron could become depolarized or hyperpolarized(even less likely for AP), depending on what kind of R was activated by the neurotransmitter(NOT the neurotransmitter itself, but is the RECEPTOR TYPE) -Depolarization -ion channels allow + charged ions to enter(inside more pos) -inside of neuron less neg; gets closer to threshold -neuron becomes more likely to fire(generate AP of its own) -Hyperpolarization
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