The nervous system biology lesson for kids: 1st, 2nd, 3rd, 4th, 5th, 6th and 7th grades biology lesson.
The bodies of humans and other animals are like complicated biological machines. There are various parts working together to keep us alive. There has to be some way for these parts to communicate, or else everything would go out of whack. One of the ways the various body parts communicate with each other is through the nervous system, which allows the body to communicate with electric signals.
The human nervous system is a network of very special cells called neurons (new-rons) or nerve cells. A neuron also has helper cells called neuroglia (which is the same in both singular and plural form!), also called glial cells. Neuroglia help the neurons by feeding, protecting them, so they’re very important! Every neuron has between 6 and 60 neuroglia, so the nervous system has more neuroglia than neurons, even though the neurons are the cells that carry around the signals around the body.
The biggest mass of neurons is the brain, which, along with the spinal cord, makes up the central nervous system. The brain is divided into lots of different sections. There are centers that process sight, sound, and touch, for example, and even others that process faces, language, and emotions! The brain is very important because it allows us to understand the world.
Some neurons are very long, and they have to be because they have to carry signals a long way. Signals are passed from one neuron to the next across gaps called synapses. At the end of each neuron is a branched section, each branch called an axon terminal. It’s here that the nerve passes the signal along to other nerves or even to muscles and other parts of the body.
From the brain, neurons extend into the spinal cord, and then groups of neurons branch out and extend to the different parts of the body. A group of neurons together is called a nerve, and there are lots of them. Nerves only exist outside the central nervous system, and this outside network of nerves is called the peripheral nervous system.
Within the peripheral nervous system, there are three types of nerves: afferent, efferent, and mixed. Afferent nerves carry signals from the sensory organs (like the skin, eyes, and ears) to the central nervous system. Efferent nerves carry signals from the central nervous system to the different parts of body (like the muscles), telling them what to do. That means that when you see food, afferent nerves tell your brain about it, and then efferent nerves tell your hands to pick it up and eat it! There are also mixed nerves, which carry signals both ways. It is a very efficient system, with no traffic or crossed signals.
The nervous system is complicated, but without it, we wouldn’t be able to do much of anything. Everything from sight, smell, hearing, and moving around all depend on nerves to carry signals and tell our body parts what to do.