The nervous system is a system in the body which sends signals around the body. It lets people and animals respond to what is around them. The "central nervous system" is the brain, the spinal cord, and nerves. It is present in most animals. It is there to coordinate movement, to process the input of the senses, and to make the animals act a certain way. It is made up of neurons and cells called glia, among other things. Glial cells keep the neurons safe and healthy.