NEUROPHYSIOLOGYNEUROPHYSIOLOGY

Anion and Cation distributionAnion and Cation distribution

[K+] 155 mEq/l

[K+] 4mEq/l

[Na+] 12 mEq/l

[Na+] 145 mEq/l

Fixed Anions

Resting Membrane PotentialResting Membrane Potential

Resting Membrane PotentialResting Membrane Potential

Na/K PumpDifferential permeabilityK DiffusionNa diffusion

Local potentialLocal potential

Action PotentialAction Potential

Action PotentialAction Potential

Depolarization to thresholdVoltage regulated gatesRepolarizationNa/K pumpAll or none

Nerve ImpulseNerve Impulse

Saltatory Conduction

Saltatory ConductionSaltatory Conduction

MyelinSpeedTemperatureSizeEfficiencyNewborns

SynapsesSynapses

Presynaptic NeuronPostsynaptic Neuron

Chemical SynapseChemical Synapse

Synaptic cleftSynaptic delay - .5-1 msec

NeurotransmittersNeurotransmitters

Synaptic vesiclesReceptorsFate ofAcetylcholine

– Acetylcholinesterase

NeurotransmittersNeurotransmitters

NorephinephrineEpinephrineDopamineCatecholaminesSerotoninAmino acids, hormones

NeuromodulatorsNeuromodulators

EnkephalinsEndorphins

Excitatory Postsynaptic Excitatory Postsynaptic PotentialPotential

EPSPEPSP

Temporal SummationSpatial Summation

Inhibitory Postsynaptic Inhibitory Postsynaptic PotentialPotential

IPSPIPSP

Hyperpolarization

Receptors

ReceptorsReceptors

Dendrite – Very specific receptorStimulusGraded

– How can we determine the stimulus intensity?

Adaptation – Which sensation does not adapt?

EffectorsEffectors

EffectorsEffectors

Neuromuscular junctionEnd-plate potential