BMS 300 1st Edition Lecture 23 Outline of Last Lecture I. Structure of the synapse -presynaptic -cleft -post synaptic II. Generation of the excitatory post synaptic potential -neurotransmitter release 1. machinery of exocytosis >V-snare >T-snare 2. fate of the neurotransmitter >the ligand gated channel >receptor ligand binding >channel opening/ion flow >uptake of neurotransmitter by glia III. Propagation of the epsp -graded potential -decrementing potential -summation of the trigger zone These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-role of the membrane resistance in passive membrane IV. Inhibition -the IPSP -role of channels >inhibitory neurotransmittersOutline of Current Lecture V. Role of inhibition in summation and synaptic integration -inhibitory neurotransmitters 1. GABA2. glycine -opening ligand-gated inotropic channels -generating the I.P.S.P1. increasing Cl- permeability 2. effect on membrane voltage through changes in membrane resistance/permeability effect on E.P.S.P amplitude V=IR3. effect on duration of E.P.S.P through effect on Rm T=RmCm VI. Myatatic reflex arc -the patellar tendon tap 1. stretch receptors in quads2. 1o sensory afferent 3. synapse on the lower motor neuron 4. effect on muscles5. role of inhibition on spinal cord Current LectureRole of inhibition in summation and synaptic integration -starting with the image of the pineapple neuron-the input region lacks v-gated channels -there is an excitatory synapse and there is an inhibitory synapse -the K+ leak channels determine the membrane resistance -if the number of leak channels is high then the membrane resistance (Rm) is low -if the number of leak channels dictate how much resistance there is -V=IR >this is the formal way of saying the leakier the membrane the amount of resistance is low -the membrane resistance (Rm) responds to the number of open Cl- channels -the higher the Cl- leak channels the lower the membrane resistance CNS Excitatory Synapse -neurotransmitter: glumate -v-gated Ca+ channels -ligand gated ionotropic channels >cation channelsInhibitory Synapse-v-gated Na+ channels -neurotransmitters: gamma amino, butyric acid, GABA, glycine -ligand gated ionotropic channel >permeable to chloride >anion channels -the membrane potential seeks the equilibrium for the ion whose permeability is dominant EPSP and IPSP-the two cancel each other out if they are the same, but biologically they are not normally the same -transmitters are divided into small molecules which are transmitters and peptides ΔV=IRM inhibition can affect Rm ΔV small when IRM is low and vice versa T=RmCm: T=durationWhen the membrane resistance is low the T will be short -inhibition reduces membrane resistance which reduces the amplitude of EPSP which reduces the duration of EPSP -duration of EPSP arriving at the trigger zone is shorter with inhibition -has an effect on spatial and temporal summationMyatatic Reflex Arc -muscle strength reflex: doctor’s office example -the fastest reflex -heavy myelinated
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