Loaiphysiologyyahoocom A ction P otential ALL x NOTHING 3 The Action Potential Resting potential 75 mV Equilibrium potential of potassium 95 mV Equilibrium potential of sodium 60 mV ID: 575587
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Slide1
Loai Alzghoul
Loai.physiology@yahoo.comSlide2
A
ction
P
otential
= ALL
x
NOTHINGSlide3
3
The Action Potential
Resting potential (-75 mV)
Equilibrium potential of potassium (-95 mV)
Equilibrium potential of sodium (+60 mV)
Electrotonic
potential
K
Na
K
K
Na
Passive increase in positive charge
- 75 mV Slide4
4
The Action Potential
Resting potential (-75 mV)
Equilibrium potential of potassium (-95 mV)
Equilibrium potential of sodium (+60 mV)
Electrotonic
potential
Opening of voltage-gated sodium channel
K
K
K
- 55 mV
Na
Na
thresholdSlide5
5
The Action Potential
Resting potential (-75 mV)
Equilibrium potential of potassium (-95 mV)
Equilibrium potential of sodium (+60 mV)
Electrotonic
potential
Depolarisation due to sodium influx
Opening of voltage-gated sodium channel
K
K
K
- 40 mV
Na
NaSlide6
6
The Action Potential
Resting potential (-75 mV)
Equilibrium potential of potassium (-95 mV)
Equilibrium potential of sodium (+60 mV)
Electrotonic
potential
Depolarisation due to sodium influx
Inactivation of voltage-gated sodium channel
K
K
K
+ 50 mV
Na
Na
voltage-gated sodium channels turn to the inactivation phaseSlide7
7
The Action Potential
Resting potential (-75 mV)
Equilibrium potential of potassium (-95 mV)
Equilibrium potential of sodium (+60 mV)
Electrotonic
potential
Depolarisation due to sodium influx
opening of voltage-gated potassium channel
K
K
+ 50 mV
Na
Na
KSlide8
8
The Action Potential
Resting potential (-75 mV)
Equilibrium potential of potassium (-95 mV)
Equilibrium potential of sodium (+60 mV)
Electrotonic
potential
Depolarisation due to sodium influx
opening of voltage-gated potassium channel
K
K
- 85 mV
Na
Na
K
Repolarization due
to potassium influxSlide9
9
The Action Potential
Resting potential (-75 mV)
Equilibrium potential of sodium (+60 mV)
Electrotonic
potential
Depolarisation due to sodium influx
K
K
- 75 mV
Na
Na
K
closing of voltage-gated potassium channel
repolarization due
to potassium influx
Repolarisation due
to potassium influx
Membrane potential approaches the
E
Na
and voltage-gated sodium channels turn to the inactivation phase
Hyperpolarising
afterpotentialSlide10
Dentistry 07
10
The Action Potential
Electrotonic
potential
Opening of voltage-controlled sodium channel
Inactivation of
voltage-controlled sodium channel
Opening of voltage-controlled potassium channel
Resting potential (-75 mV)
Equilibrium potential of sodium (+60 mV)
threshold
Hyperpolarization due to more outflux of potassium ionsSlide11
11
Properties of action potentials
Action potentials:
are all-or-none
events
threshold
-70
+60
mV
Stimulus
0
APs
do not summate - information is coded by frequency not amplitude.Slide12
Dentistry 07
12
Recording membrane potential
+ 60 -
+ 30 -
0 -
- 30 -
- 60 -
- 90 -
mV
Electrotonic potential
Localized non propagated
Action potentialSlide13
Graded PotentialsSlide14
Excitabl
e cell:
NEURON and
MUSCLE CELLSlide15
Neuron
F8-2
Axons
carry information from the
cell body
to the axon terminals.
Axon terminals
communicate with their target cells at
synapses
.Slide16Slide17
Communication Between Neurons
Electrical synapse Chemical synapseSlide18Slide19
Dentistry 07
19
It is recorded by cathode ray oscilloscope
it is negative in polarized (
resting, the membrane can be excited
) state with the potential difference inside the cell membrane is negative relative to the outside.
Recording of Resting and action potentials
+
+
+
+
+
+
+
+
+
+
+
–
–
–
–
–
–
–
–
–
–
–
Voltmeter
–
+
0 mV
-70 mV
+Slide20
Terminology Associated with Changes in Membrane Potential
F8-7, F8-8
Depolarization
- a decrease in the potential difference between the inside and outside of the cell.
Hyperpolarization
- an increase in the potential difference between the inside and outside of the cell.
Repolarization
- returning to the RMP from either direction.Overshoot
- when the inside of the cell becomes +ve due to the reversal of the membrane potential polarity.Slide21Slide22