Conduction of action potential
Action potential is the brief electrical signal that travels along the membrane of a nerve cell or neuron. The conduction of action potential involves a series of steps that allow the signal to be transmitted from one end of the neuron to the other.
1. Resting membrane potential: At rest, the neuron has a slightly negative charge inside compared to the outside due to the unequal distribution of ions across the cell membrane. This resting membrane potential is around -70mV.
2. Depolarization: When a stimulus activates the neuron, sodium channels open in the cell membrane, allowing sodium ions to rush into the cell. This causes the inside of the cell to become momentarily more positive, reaching around +30mV in a process called depolarization.
3. Repolarization: Potassium channels then open, allowing potassium ions to move out of the cell, restoring the negative charge inside the membrane. This causes the cell to return to its resting membrane potential.
4. Hyperpolarization: Sometimes, the cell may overshoot the resting membrane potential and become more negative than usual. This is called hyperpolarization and helps to ensure that the action potential is distinct and does not overlap with other signals.
5. Refractory period: After an action potential, the neuron enters a refractory period where it is temporarily unable to generate another action potential. This helps to ensure that the signal travels in one direction along the neuron.
6. Action potential propagation: As the action potential is generated at one end of the neuron, it travels down the length of the cell membrane through a process called saltatory conduction. In myelinated neurons, the action potential jumps from one node of Ranvier to the next, increasing the speed of transmission.
Overall, the conduction of action potential is a complex electrochemical process that allows neurons to communicate with each other and transmit signals throughout the nervous system.