Boyd Henshaw, age 13, of Seattle WA
How does the nervous system work?
Imagine a large and powerful computer that could sift masses of data, solve problems and give and take orders. It could have a radio, telephone system and TV screens. It could have a warning system to alert us to enemy attack and, in emergency, take fast action on its own initiative, Such a machine could solve some problems better and faster than you could. But in most respects, the human nervous system is just as capable as this giant computer.
The key factor in the nervous system is organization. It is made from billions of specialized, living cells called neurons, some of which are centralized and some spread throughout the body. Working together, they sift an endless stream of data from the eyes and other sense organs. They warn of danger, make decisions, give orders and carry out many bodily functions without help from the conscious m1nd. They work by impulses of an electrical nature similar to those which activate the fabulous computer.
The brain and spinal cord are headquarters for this miraculous operation. The field work is done by a network of sensory and motor neurons spread throughout the body. Sensory neurons carry impulses to headquarters. Motor neurons carry messages from headquarters. Many of these neurons are slender threads several feet long. Each has a cell body, a small blob of grey matter which feeds it and makes repairs to the damaged thread. But a nerve cell body cannot repair itself.
The tip of a sensory neuron reaching, say, the end of a finger, fans out into a number of still finer threads just below skin surface.
Each of these threads has a sensitive tip. When you touch a hot stove, impulses from this neuron flash to headquarters, There the data is estimated, a decision is made and orders flashed to motor neurons almost instantly, The motor neurons carry the orders and stimulate the muscles to carry them out.
If the situation is urgent, all this will be done before your conscious mind has time to think, This is what happens when you jump away from a hot stove before you know it, Many other operations are carried on automatically. Digestion, breathing and circulation are just a few of the operations carried on by the automatic nervous system, day and night,
This does not mean that your conscious mind has no decisions to make. If your feet are cold, for example, you will be given time to decide what to do about it. The brain forms a picture from the impulses coming to it from the eyes. But your conscious mind must decide whether you will find something worthwhile in what you see, Your ears may report the howling of coyotes. Your conscious mind must decide whether you will grin and bear it, throw a shoe or enjoy the glee club.