How is the resting potential maintained in a neuron?

The resting potential in a neuron is maintained by the sodium-potassium pump and the differential permeability of the neuron's membrane.

The resting potential of a neuron, typically around -70 millivolts (mV), is a state of electrical charge that is maintained when the neuron is not transmitting any signals. This is achieved through a combination of active and passive transport mechanisms, primarily involving sodium (Na+) and potassium (K+) ions.

The sodium-potassium pump, an active transport mechanism, plays a crucial role in maintaining this resting potential. This pump uses energy from ATP to move three sodium ions out of the neuron for every two potassium ions it moves in. This creates a net negative charge inside the neuron, contributing to the resting potential.

In addition to the sodium-potassium pump, the differential permeability of the neuron's membrane also helps maintain the resting potential. The membrane is more permeable to potassium ions than to sodium ions, which means potassium ions can move out of the neuron more easily than sodium ions can move in. This further contributes to the net negative charge inside the neuron.

The balance between the active transport of ions by the sodium-potassium pump and the passive movement of ions due to the membrane's differential permeability is what maintains the resting potential. If this balance is disrupted, for example by a stimulus that causes the neuron to fire, the neuron will undergo a process called depolarisation. This involves a rapid influx of sodium ions, which temporarily reverses the charge inside the neuron. However, once the stimulus has passed, the sodium-potassium pump and the differential permeability of the membrane will restore the resting potential.

In summary, the resting potential in a neuron is maintained by the sodium-potassium pump actively transporting ions against their concentration gradients, and the differential permeability of the neuron's membrane allowing passive movement of ions down their concentration gradients. These mechanisms work together to maintain a net negative charge inside the neuron, which is the neuron's resting potential.