Page 60 - Color_Atlas_of_Physiology_5th_Ed._-_A._Despopoulos_2003

A. Action potential (1) and ion conductivity (2) (nerve and skeletal muscle)
1 2
+ “Overshoot” +
(20–30mV)
0 0
– Repolarization Action –
(ca. –70 to –90mV) Membrane potential E m (mV) Threshold Depolarization After-hyper- Ion conductance g g K E m (mV) Action Potential
potential
g Na
Action
potential

polarization
Resting potential Pre- ca. 1ms Time Resting 0 ca. 1ms Time
G K
depolari-
Resting
sation
G Na
+
B. Voltage-gated Na channel Plate 2.3
1. Closed, [mV]
activatable
+ Depolarization
0
–
–90mV [mV]
Resting potential Na + +
0
2. Open –
+
Na channel
Depolarization
Tetrodotoxin (first 0.5ms)
Complete
repolarization
Veratridine
Batrachotoxin 4 Tetrodotoxin
Na + (TTX)
[mV] Out
3. Closed,
inactivated +
0
–
Reversal of potential
and start of
repolarization
In
47

Despopoulos, Color Atlas of Physiology © 2003 Thieme
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