What are Nerves?
All living things are made up of cells. Scientists use the word ‘organism’ for living things. Complicated organisms like the human body are made up of many different kinds of cells that do different jobs.
Neurons are one such group of cells. Neurons are also called nerve cells. Neurons have the ability to pass signals and messages from one part of the body to another. Neurons get together to form nerves of our body.
A nerve is like an electric cable that passes electric current. It carries signals between parts of the body.
Some companies and offices we know have many branches and a ‘head’ office. The head office is where all the important decisions are made. The head office tells the other branches what to do. Brain is the ‘head’ office of the body. It receives messages from all the other parts of the body and tells them what to do. It is the nerves that carry messages to and from the brain.
When your hand touches a hot iron, the hand sends the sensation to the brain through nerves. The brain recognizes that it is hot, and so commands your hand to withdraw! Now you know how fast your hand pulls back when you touch a hot iron by mistake. This means that the business of sending the signal to the brain and its reply took only fraction of a second. Our brain and the nerves together are still many times faster than the fastest internet connection we have!
We do many things because we decide to do so- walking, talking, writing are all examples. These are called voluntary actions. But there are also other things inside our body- like the beating of our heart, digestion of food etc that go on without our awareness. These are called involuntary actions. Nerves control every action of our body- voluntary and involuntary.
Nerves use a complex process using chemical and electrical changes to carry messages.
The head office of our body, the brain, is all computerized. In fact brain is quite like a supercomputer. So we may say that this computer is ‘wired’ to other parts of body using nerves. The most important or central of these wires is the spinal cord that runs down from the brain through the back. Many nerves branch out from the spinal cord to reach parts of the body.
Our spinal cord is about 18 inches long and ¾ inches thick.
Our brain and the spinal cord are thus extremely important parts of the body. Both are protected by bone. Skull covers our brain. The spinal cord is covered by 33 ring shaped bones called vertebrae. These 33 vertebrae together are also called the spinal column or the backbone. The backbone is thus not a single bone, but a group of bones.
Our brain works round the clock- that means even when we are asleep- as things like working of the heart have to go on at all times. No part of our body can do its job, even for a moment, without talking with our brain.Spinal cord is the place from where nerves to different parts of the body branch out. We saw that our body cannot work if connection with the brain goes bad even for a moment. As the spinal cord is the first main wire to carry this communication process, we need to take special care of our spinal cord.