NSCI 110 1st Edition Lecture 11 Outline of Last Lecture I Current and voltage clamps allow you to measure changes in membrane potential or current flow respectively II Self propagation is a key property of neurons III IV V a Once the action potential is initiated it is able to move down the axon in an allor none fashion Axon hillocks have the highest concentration of voltage gated sodium channels a Conduction normally begins here and travels toward the terminal end b Orthodromic vs antidromic conduction Saltatory conduction allows action potentials to travel rapidly down an axon Electrical properties at the synapse a No electrical threshold b Graded summation c Decremental response Outline of Current Lecture I Temporal and spatial summation may lead to either hyperpolarization or depolarization of a neuron II There are several crucial differences between an action potential and synaptic potential III Synapses can be classified according to where on a neuron the release of neurotransmitters occurs IV Synaptic transmission a Docking and priming b Action potential reaches axon terminal i Gated calcium channels open c Transmitter is released and travels to post synaptic membrane Current Lecture I II III Graded potentials reflect the magnitude of stimulation Temporal summation occurs when two potentials occur close to the same time a Provides a greater depolarization hyperpolarization than either of the two individually b Spatial summation is a similar mechanism Comparison of action potential vs synaptic potential a Action potential 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 IV V i Voltage threshold ii All or none iii Self propagating b Synaptic potential i No threshold ii Graded iii Decremental Synapse the basics a Pre post synaptic membranes i Axon terminal holds vesicles storage granules microtubules mitochondria b Many types of synapses i Dendrodendritic ii Axodendritic iii Axoextracellular iv Axosomatic v Axosomatic vi Axosynaptic vii Axoaxonic viii Axosecretory c Type I synapses are excitatory and type II are inhibitory Overview of synaptic transmission a Transmitter is synthesized and stored in vesicles and or endosomes b Docking and priming active zone i Active zone is where primary site of vesicles docking near pre synaptic membrane occurs ii Once vesicles are in this position docking they are ready to release the transmitters once an action potential reaches the axon terminal c Action potential invades terminal i Voltage gated calcium channels become activated 1 Causes molecular tethers to contract and bring vesicles into contact with pre synaptic membrane ii Exocytosis causes vesicles to merge with the pre synaptic membrane at the active zone and release the transmitter iii Endocytosis will allow the membrane to pinch off extra membrane formed by the fusion of the vesicles and halts the release of transmitters 1 Pinches off gammas d Transmitter binds to receptor on post synaptic membrane i Opens or closes ion channel 1 Sodium influx when channel opens and contributes to depolarization
View Full Document
Unlocking...