L6_NPB_101

L6_NPB_101 - Lecture6 OnlineHandouts: Lec6Notes...

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Unformatted text preview: Lecture6 OnlineHandouts: Lec6Notes Announcements: Correc7onLec2,slide10: shouldread"hydrophobic" not"hydrophilic" Review Synapse Organiza7onofthe NervousSystem Reading(Recommended): Reading:Ch5 REV:Ac7onPoten7al 1. RapidstereotypedchangeinEm,whichoccursin responsetoas7mulus. 2. Thereare6primarycharacteris7csofanAP: a) Largeregenera7veincreaseinPNaviaPosi7ve Feedback b) Rapidrepolariza7onofEmbyslowincreaseinPK c) EveryAPfollowedby2refractoryperiods d) EveryAPisAllorNone e) APconductedovertheaxon f) APareconductedrapidly Synapses Junc7onbetweentwoneurons Primarymeansbywhichoneneurondirectlyinteracts withanotherneuron GeneralAnatomyofasynapse Presynap)cneuronconductsac7onpoten7altoward synapse Synap7cknobcontainssynap7cvesicles Synap7cvesiclesstoresneurotransmiYer(carriessignalacrossa synapse) Synap)ccle0spacebetweenthepresynap7cand postsynap7cneurons Postsynap)cneuronneuronwhoseac7onpoten7alsare propagatedawayfromthesynapse GeneralSynapse AP SYNAPTICCLEFT Fig.416a,pg.103 POSTSYNAPTICCELL AnatomyofaChemicalSynapse Presynaptic axon terminal Voltage-gated Ca2+ channel Synaptic knob Ca2+ Neurotransmitter molecule Synaptic cleft Synaptic vesicle Subsynaptic membrane Chemically gated ion channel for Na+, K+, or ClReceptor for neurotransmitter Postsynaptic neuron Fig.416a,pg.103 SynapsePhysiology Synap7ctransmission ProcessofconversionofelectricalAPinforma7on intochemicalEmchangeinpostsynap7ccell. Occursin8steps 1) AxonAPdepolarizesAxonterminal. 2) Ca+2permeabilityincreasedbyopeningvoltage sensi7veCa+2channels(ECaisPosi7veEm). 3) ChemicalNeurotransmiYerreleasedasCa+2incell leadstofusionofsynap7cvesiclestopresynap7c membraneandexocytosisofvesicles. SynapsePhysiology(cont'd) 4) DiffusionofNTacrosssynap7cclea. Release/diffusiontake7me(~0.5mSec);synap7cdelay. 5) NTbindstoreceptorsinpostsynap7cmembrane. 6) Postsynap7cresponse: open/closechemicallygatedionchannels. increase/decreaseionpermeability. Increase/decreaseionflowthroughpostsynap7cmembrane. Quantal/gradedresponsenotallornone. 7) 2basictypesofresponseExcitatory&Inhibitory 8) RemovalofNTfromsynap7ccleaspecialized mechanismslimitamountof7meNTispresent. TheChemicalSynapse Presynaptic axon terminal Voltage-gated Ca2+ channel Synaptic knob Ca2+ Neurotransmitter molecule Synaptic vesicle Synaptic cleft Subsynaptic membrane Chemically gated ion channel for Na+, K+, or Cl- Postsynaptic neuron Fig.416a,pg.103 Receptor for neurotransmitter Presynap7c&Postsynap7c Membranes Vesicularfusionand NTrelease NTdiffusion Bindingapostsynap7c receptor Ionflow Fig.416b,pg.103 NeurotransmiYers Varyfromsynapsetosynapse SameneurotransmiYerisalwaysreleasedatapar7cularsynapse Quicklyremovedfromthesynap7cclea SomecommonneurotransmiYers Acetylcholine Dopamine Norepinephrine Epinephrine Serotonin Histamine Glycine Glutamate Aspartate Gammaaminobutyricacid(GABA) Synap7cPoten7als Signalatsynapseeitherexcites(+)orinhibits ()thepostsynap7cneuron Signdependsupondirec7onofEmchange ExcitatoryisEmdepolariza7onclosertoThreshold InhibitoryisEmhyperpolariza7onfartherfrom Threshold Excitatorysynapses Inhibitorysynapses Twotypesofsynapses ExcitatoryPostsynap7cPoten7als EPSP:cellmoreexcitable NTopensachemically gatednonspecificca7on channel. IncreasePNaandPK GreatertendencyforNa+ toentercell(rememberEi) Resultsindepolariza7on SmallchangeinEm Gradedpoten7al Fig.417a,pg.104 InhibitoryPostsynap7cPoten7als IPSP:celllessexcitable NTopensachemically gatednonspecificK+orCl channel. IncreasePKorPCl GreatertendencyforK+to leavecellorCltoentercell (rememberEi) Resultsinhyperpolariza7on SmallchangeinEm Gradedpoten7al Fig.417b,pg.104 Summa7onofSynap7cInput Excitatory presynaptic inputs Recording potential of postsynaptic cell Temporal summation Spatial summation EPSPIPSP cancellation Recording potential of postsynaptic cell Inhibitory presynaptic input Threshold potential Resting potential Fig.418,pg.106 Summa7onofSynap7cInput MorphologyofanElectricalSynapse Cell 1 cytosol Cell 2 cytosol Connexon Gap junction Diameter of channel = 1.5 nm Longitudinal section of connexon Passage of ions and small molecules No passage of large molecules 24 nm Interacting plasma membranes Fig.36,pg.60 NervousSystem Func7onsoftheNervousSystem Input(Afferent) Integra7on Transduceinforma7on(converts7muliintoelectrical signal) Communica7on(transferinforma7on) Processingandintegra7onofsignals Output(Efferent) Genera7onofresponsesandcontrolofac7vi7es Homeosta7cRegula7on Highercogni7vefunc7on ...
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This note was uploaded on 04/17/2008 for the course NPB 101 taught by Professor Fuller,charles/goldberg,jack during the Spring '08 term at UC Davis.

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