How does the nervous system work?

A cord of nerves that leaves the base of the brain and runs down inside the spine. It carries messages from the brain to the body and back. It is not the same as bone marrow, which is inside bones and makes blood.

An automatic, very fast response, like pulling your hand away from something hot. The message only goes as far as the spinal cord, which answers right away, even before the brain notices the pain.

It depends on the nerve. The fastest reach about 120 meters per second, over 400 km/h. The slowest, like some pain fibers, travel under 2 meters per second.

It is the nervous system’s cell. It has a body, several little "branches" that receive messages and one long extension that sends the message to the next cell. Neurons talk to each other using tiny chemical substances.

When you stay in one position for a long time, the nerve gets squeezed and sends fewer signals. When you move, it wakes up bit by bit and sends jumbled signals, which we feel as pins and needles. If it happens for no reason or often, see a doctor.