How are nerve impulses generated and propagated along a neuron?

Nerve impulses are generated and propagated along a neuron through a process called action potential.

In more detail, the process begins at the neuron's cell body, where an electrical signal is generated. This signal, or nerve impulse, is created by a change in the electrical charge across the neuron's cell membrane. This change in charge is caused by the movement of ions, specifically sodium and potassium, in and out of the neuron.

The process starts with the neuron at its resting state, where the inside of the neuron is negatively charged compared to the outside. This is due to the distribution of sodium and potassium ions across the neuron's membrane, maintained by the sodium-potassium pump. When a stimulus is received, the neuron's membrane at the point of stimulus becomes permeable to sodium ions, causing them to rush into the neuron. This influx of positive ions changes the charge inside the neuron, making it positive compared to the outside. This is called depolarisation and marks the start of the action potential.

The action potential then propagates along the neuron in a wave-like manner. As the sodium ions rush into one section of the neuron, they cause the next section of the neuron's membrane to become permeable to sodium ions, repeating the process. This continues along the length of the neuron, effectively transmitting the nerve impulse from the cell body to the end of the neuron.

Once the action potential has passed, the neuron needs to reset itself back to its resting state. This is achieved through a process called repolarisation, where the sodium ions are pumped out of the neuron and potassium ions are pumped back in. This restores the negative charge inside the neuron, readying it for the next action potential.

In summary, the generation and propagation of nerve impulses along a neuron involve a complex interplay of ions and changes in electrical charge. This process, known as action potential, allows neurons to transmit signals quickly and efficiently across long distances.