neurophysiology of nerve impulses with fonts.pptx

8/18/2019 Neurophysiology of Nerve Impulses with Fonts.pptx

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• Frequency – number of actionpotentials per second

• Interspike Intervals

• Conduction Velocity

• Myelination – Glial cells

– CNS: li!odendrocytes

– "NS: Sc#$ann cells

– Nodes of %anvier

Introduction


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• Synaptic vesicles – Neurotransmitters

– C#emical Synapse

– "ostsynaptic potential

• Calcium & Ma!nesium ions

• %estin! membrane potential: '() mV

• Sensory neurons* motor neurons* &interneurons

Introduction


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• Nerve C#amber – $#ere t#e a-on is nerve isplaced

• scilloscope ' observe timin! of stimuli and

volta!e c#an!es in t#e a-on• Stimulator ' sets t#e stimulus volta!e and to

deliver pulses t#at depolari/e t#e a-on

• %ecordin! electrodes ' records volta!e

c#an!es in t#e a-on• Microelectrodes

• 0ook electrodes

Met#odolo!y


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1 2) mV pulse$as deliveredto t#e a-on for

)34 msec


4)) msec


4)) msec

1 64 mV pulse$as deliveredto t#e a-on for

4)) msec

8sec

9

Met#odolo!y 1ctivity


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Materials & Met#ods

• ;ar!e'diameter

• 0eavilymyelinated

• Sensory

"aciniancorpuscle

• Medium'diameter

• ;i!#tlymyelinated

• Visceral

sensory myelinated• lfactory

sensoryneuron

•

Free nerveendin!

1ctivity (

A fber C fberB fber


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Met#odolo!y =?' di ko kasi m#anap yun! katulad sayo na format ika$ na b#ala ditey33t#anksand yun! m!a

pa!prinesent Malaki

Fiber $asclicked toput t#ea-on in

t#e nervec#amber

Stimulusduration

$as set to)34

millisecond for all


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Neuron $asimmersed incontrol Ca2

e-tracellularsolution

Neuron $asimmersed ine-tracellular

solution$it#out Ca2

Neuron $asimmersed in

lo$ Ca2

e-tracellularsolution

Neuron $asimmersed incontrol M!2 e-tracellular

solution

=#e stimulator $as used to deliver a lo$ intensity and #i!#

intensity pulse to t#e neuron

1ctivityDMet#odolo!y


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1 very $eakstimulation $asdelivered to t#ereceivin! end of

t#e sensoryreceptor

1 moderatestimulation $asdelivered to t#ereceivin! end of

t#e sensoryreceptor

1 stron!stimulation $asdelivered to t#ereceivin! end of

t#e sensoryreceptor

Met#odolo!y 1ctivityE


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• 2) mV

• )34 msec

1ctivity


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• 2) mV

•

4)) msec

1ctivity


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• 5) mV

•

4)) msec

1ctivity


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• 64 mV

•

4)) msec

1ctivity


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• 1ction potential frequency –@AISI8sec9

• ,ect of increased stimulus intensityon t#e frequency of action potentials:increase

1ctivity


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• 1


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• B


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• C


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• Conduction velocity is calculated by

dividin! t#e distance bet$een %@ and%2 8)3@ m9 by t#e time it took for t#eaction potential to travel from %@ to %2

• Greater diameter and myelination*

faster conduction

1ctivity (


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Summary of %esults:

Stimulus

Intensit

y

Number of

synaptic vesicles

e-ocytosed in

Control Ca2

Number of

synaptic vesicles

e-ocytosed in No

Ca2

Number of

synaptic vesicles

e-ocytosed in

;o$ Ca2

Number of

synaptic vesicles

e-ocytosed in

M!2

;o$

Intensit

y

2 ) @ @

0i!#

Intensit

y

) 5 5


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+iscussion

• Calcium 8Ca2C9is a vital element int#e process of neurotransmitterrelease from t#e a-on terminal

• =#e e-ocytosis of synaptic vesicles iscalcium dependent

• Ma!nesium 8M!29 competes $it#

t#e calcium ions in attac#in! to t#evolta!e'!ated calcium c#annel


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1ctivityE

i i E


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• Sensory neurons receive t#e stimuli

and communicate $it# interneurons$#ic# process t#e information andcommunicate $it# motor neurons

•

%estin! membrane potential is t#esame in t#e sensory neuron and t#einterneuron

1ctivity E

1 i i E


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• eak stimulus

• Small depolari/in! response at %@

1ctivity E

1 ti it E


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• Moderate stimulus

• ;ar!e depolari/in! response at %@

1ctivity E

1 ti it E


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• Stron! stimulus

• ;ar!e depolari/in! response at %@ and %5

1ctivity E


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Conclusions

• 1n increase in t#e stimulus intensity also increases t#eaction potential frequency3

• 1


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Conclusions


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• Neuro!lial Cells3 82))@93 %etrieved from#ttp:AA$$$3ncbi3nlm3ni#3!ovAbooksANB@)DEA

• =#e nervous system3 82))D93 %etreived from#ttp:AAlrrpublic3cli3det3ns$3edu3auAlrrSecureASitesA;%%Vie$A(())AdocumentsA44(A44(A44(J)43#tm

neurophysiology of nerve impulses with fonts.pptx

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