Channels open clacium triggers exocytosis nt diffuses

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Unformatted text preview: of neurotransmitters Electrical Potential in Biological Systems Establishment of Neuronal RMP Equilibrium potentials for potassium and sodium ions RMP of neurons is approximately - 70 mV More – charges inside/ more + charges outside 1) Action Potential Voltage Gated Calcium channels open Clacium triggers exocytosis NT diffuses and binds to receptor Response in cell Response is terminated by removing NT from synaptic cleft Degradation Reuptake Diffusion Synaptic delay: - 0.5–5 msec between arrival of AP and change in postsynaptic Vm - not related to diffusion of neurotransmitter across cleft - caused by changes in [Ca++] and release of neurotransmitter Signal Transduction at Synapses Channel linked receptors/ionotropic receptor Fast and direct acting G protein linked receptors/metabotrophic receptors Slow acting Post- Synaptic potentials PSP: change in membrane potential in response to receptor- neurotransmitter interaction Some are excitatory, graded potentials Some are inhibitory EPSP: brings membrane potential closer to threshold, depolarization IPSP: brings membrane potential further from threshold, hyperpolarization Neurotransmitter binds to receptor, K+ or Cl- moves. K+moves out if channels open (IPSP) Chloride is sometimes a stabilizer of potentials against changes via “inhibitory” Cl- channels The summing of input from various synapses at the hillock of the postsynaptic neuron will generate AP Summation: Adding the effects of graded potentials IPSPs and EPSPs are graded potentials Can be summer Types of summation: Temporal: one synapse through time Spatial: several synapses Frequency coding: Degree of depolarization is signaled by the frequency of action potentials Summation effects depolarization Summation influences frequency of AP...
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This document was uploaded on 03/23/2014 for the course BIOL 175 at Georgetown.

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