What is polarization in action potential?

As a neuroscientist with a focus on cellular neuroscience, I can explain the concept of polarization in the context of an action potential. Polarization in the context of an action potential refers to the difference in electrical charge across the cell membrane of a neuron. When a neuron is at rest, it is in a state of polarization, which is characterized by a negative charge inside the cell relative to the outside. This is known as the resting potential. The resting potential is maintained by the sodium-potassium pump, which actively transports sodium ions out of the cell and potassium ions into the cell, creating an imbalance in charge. When a stimulus is strong enough to depolarize the neuron, it triggers the action potential. During an action potential, voltage-gated sodium channels in the neuron's membrane open, allowing sodium ions to rapidly flow into the cell. This influx of positively charged sodium ions makes the inside of the cell more positive, or depolarizes it. If the depolarization reaches a certain threshold, it triggers more sodium channels to open, leading to a rapid and self-propagating wave of depolarization that travels down the neuron's axon.

When the neuron is inactive and polarized, it's said to be at its resting potential. It remains this way until a stimulus comes along. Action potential: Sodium ions move inside the membrane.