Describe the process by which an action potential is generated.

The generation of an action potential is a fundamental electrical event in neurons that begins with the depolarization of the neuron's membrane. This occurs when the membrane potential of a neuron becomes less negative (or more positive) than its resting potential, which is typically around -70 millivolts.

When a neuron receives a sufficient level of stimulation, voltage-gated sodium channels in the membrane open. Sodium ions (Na+) rush into the cell due to both the concentration gradient and the electrical gradient, causing a rapid change in membrane potential. This influx of positive charge leads to further depolarization of the membrane. If the depolarization reaches a critical threshold (usually around -55 millivolts), an action potential is initiated.

Once the action potential is triggered, this change in membrane potential travels along the axon as a wave of depolarization, allowing for the transmission of electrical signals in the nervous system. After reaching the peak of the action potential, potassium channels open, allowing K+ to exit the neuron, and the membrane begins to repolarize, returning to its resting state.

This process is essential for the communication between neurons and the functioning of the nervous system as a whole.