WHY IS a neuron electrically active?

A neuron is electrically active because of the difference in electrical potential across its cell membrane. This difference is created by the differential distribution of ions (sodium, potassium, and chloride) between the inside and outside of the cell.

When a neuron is at rest, the inside of the cell is negative relative to the outside. This is because there are more potassium ions inside the cell than outside, and more chloride ions outside the cell than inside.

When a neuron is stimulated, the sodium-potassium pump in the cell membrane opens up, allowing sodium ions to flood into the cell and potassium ions to flow out. This causes the inside of the cell to become positive relative to the outside.

This change in electrical potential is called an action potential. Action potentials travel down the neuron's axon, carrying information from the cell body to the synapses.

At the synapse, the action potential causes the release of neurotransmitters, which are chemical messengers that bind to receptors on the postsynaptic neuron. This binding can cause the postsynaptic neuron to either fire an action potential of its own or to inhibit the firing of an action potential.

In this way, neurons communicate with each other and transmit information throughout the nervous system.