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Vrev= (58mV/z) Log10[X]outside/[X] inside
For K+
= (58/1) Log10 5/140
=58*-0.9
Membrane potential =-52.2
For Na+
58 Log10150/15
=58 Log1010 = 58*1
Membrane potential = 58
For Cl-
58/1 Log10120/10
58 Log1012
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62.59
| Ion | Concentration inside cell | Concentration outside | Concentration gradient | Voltage gradient |
| K+ | 140 mM | 5 mM | -135 | -52.2 |
| Na+ | 15 mM | 150 mM | 135 | 58 |
| Cl- | 10 mM | 120 mM | 110 | 62.59 |
| Anions | 100 mM |
| Voltage Gated K+ | Open | Response to depolarization |
| Voltage Gated Na+ | Open | Response to depolarization |
| Leaky K+ | Usually Open | Response to ligand binding |
The negative sign shows that the inside is relatively negatively charged w.r.t to the outside.
a) The equation remains the same since chloride channels does not change the membrane potential. therefore the equation will be:
b) Membrane potential is given by:
Membrane potential is
=62*log ((5+3)) / (140+0.3)
=62log0.017
=-109.48
c) When the sodium permeability is larger:
=62*log ((5+150)) / (140+15)
=62log1
= 0
The new value 0f the membrane potential is ≥ 0
d) PNa has to e 50 – 75 more permeable than PK
e) When the sodium channels closes, the K channels opens allowing K ions to flow out- hyperpolarizing – ringing the cell to resting potential
Diffusion – This is where the neurotransmitter drifts away, out of the synaptic cleft.
Enzymatic degradation – A specific enzyme changes the structure of the neurotransmitter so that it is not recognized.
Re – uptake – This is where the entire neurotransmitter molecule is returned into the axon terminal that produced it.
In an onset of conduction, action potential is generated near the cell body portion of the axon. These are as a result of movement of ions across neural membrane. When the concentration of the ions on the inside of the neuron changes, the electrical property of the membrane changes. The influx and out flux of ions makes the inside of the target neuron more positive i.e. depolarized. When the depolarization reaches threshold, an electrical signal is generated which is then propagated along to the axon terminals where the neurons sends the OUTPUT to the other neurons
