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SECTION 12-4Neurophysiology: Ions and Electrical Signals(Fisiologi neuron: Ions dan Signal listri!
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Cell "e"#rane
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Ionic Relations in the Cell
The sodium/potassium ATPase produces a concentration of Na+ outside the cell that is
some 10 times greater than that inside the cell
a concentration of K+ inside the cell some 20times greater than that outside the cell.
The concentrations of chloride ions (Cl! andcalcium ions (Ca2+! are also maintained at
greater le"els outside the cell #$C#PT that someintracellular mem%rane%ounded compartmentsma& also ha"e high concentrations of Ca2+ (greeno"al!
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Ada ' saluran ger%ang
Kimia "oltase dan me)ani)
Three types o$ acti%e channels-che"ically regulated channels-%oltage-regulated channels
-"echanically regulated channels
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&ated Channels (saluran ger#ang!
Figure 12.13
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E'cita#le cell: NE)ON
structure:
dendrites *ith synapses
#ody
a'on *ith "yelin and synapses
$unction:
thresholding o$ input signals
integration (te"poral and
spacial! o$ input signals
generation o$ action potentials
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Intoduction to the )esting +otential (pengantartentang ,e#ran +otensial Istirahat!
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ction +otential . // ' NOT0IN&
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Appears *hen region of ecita%le mem%rane
depolari,es to threshold -teps in"ol"ed
em%rane depolari,ation and sodium
channel acti"ation (mem%ran depolarisasiNa+ tera)ti"asi!
-odium channel inacti"ation ()emudiannon a)tif!
Potassium channel acti"ation (K+tera)ti"asi !repolarisasi
eturn to normal permea%ilit& ()em%ali
)e normal!
ction +otential (+otensial asi!
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Figure 12.16.2
Figure 121 The &eneration o$ an ction+otential
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ction +otential
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ction +otential . opening o$ sodiu" and potassiu" channels
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ction +otential
K+
-channels
Na+-channels
Vm
excitable cell
time
resting potential
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T&pe A fi%ers
T&pe fi%ers
T&pe C fi%ers
ased on diameter m&elination andpropagation speed (erdasar m&elinasi dan)ecepatan propagasi!
'on classi$ication (3lasi$iasi ason!
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uscle tissue has higher resting potential (Ple%ih tinggi!
uscle tissue action potentials are longer lasting(lama %era)hir!
uscle tissue has slo*er propagation of action
potentials (propagasi le%ih lam%at!
Animation: The action potentialPLAY
,uscle action potential %ersus neural actionpotential
http://facstaff.bloomu.edu/gwassmer/ap1/media_cd/ip/systems/actpot.htmlhttp://facstaff.bloomu.edu/gwassmer/ap1/media_cd/ip/systems/actpot.html -
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