Neurophsiology- The Action Potential
Objectives
By the end of this section, the student will be able to:
- Describe the components of the membrane that establish the resting membrane potential.
- Describe the changes that occur to the membrane that result in the graded potential.
- Describe the changes that occur to the membrane that result in the action potential.
- Describe variations in the propagation of the action potential along the neuron.
Neurons even work sort of like electrical wires. Electrical wires conduct a flow of electrons we know as electricity or electrical current. Neurons conduct impulses that are electrical in nature. A neuron's impulse or signal is called an action potential. This action potential is electric in nature but it involves ion movement and not electron movement.
The term potential (membrane potential) is short for potential difference. If you have had a physics course and studied electricity, then you may know something about this topic already. Potential difference refers to a separation of charge. For example, in a battery there is a positive pole and a negative pole, these different areas represent separation of charge. An electric potential also exists across cell membranes. In muscle cells and neurons, there is a much greater potential difference than in other cells. There are more positive ions outside the neuron and muscle cell membrane than inside the cell. This is the separation of charge. The outside of the cell is more positive than the inside of the cell. We could say the inside of the cell is less positive but it is easier to refer to the inside of the cell as negative. Remember to think in terms of positivity, however.
