Action Potential

An action potential is the brief electrical impulse that travels down the axon of a neuron. It is a key mechanism for communication within the nervous system. The process of generating and transmitting action potentials is essential for various functions such as movement, sensation, and cognition.

Key Concepts

1. Resting Potential: The resting potential of a neuron refers to its stable, negative charge when it is not sending signals. This is maintained by the unequal distribution of ions inside and outside the neuron's cell membrane.
2. Threshold: The threshold is the level of depolarization required to trigger an action potential. Once the threshold is reached, the neuron fires an action potential.
3. Depolarization: When the neuron receives a signal, it undergoes depolarization, causing a reversal of the charge across the cell membrane. This shift in charge triggers the action potential.
4. Action Potential: The action potential is a rapid change in the neuron's membrane potential, resulting in the transmission of an electrical signal along the axon.
5. Propagation: Action potentials propagate along the axon, moving in one direction from the cell body to the axon terminals.
6. Refractory Period: After an action potential, the neuron enters a brief refractory period during which it cannot generate another action potential. This ensures that the signal moves in a unidirectional manner.

Study Guide

Here are some key points to focus on when studying action potential:

1. Understand the role of ion channels in generating and propagating action potentials.
2. Compare and contrast resting potential and action potential in terms of membrane potential and ion movements.
3. Explain the importance of the refractory period in maintaining the directionality of action potential propagation.
4. Describe the sequence of events leading to the generation of an action potential, including depolarization, repolarization, and hyperpolarization.
5. Discuss the factors that affect the speed of action potential conduction along an axon, such as myelination and axon diameter.

Understanding the mechanisms of action potential is crucial for grasping the fundamentals of neural communication and signaling in the nervous system.