Nan Williams, age 10, of Ruston, Louisiana, for her question:
Why does the cold make us shiver?
The human body performs numerous duties automatically, without our permission. This is fine, because nobody knows enough to tell it how to digest its food, keep its heart beating and dozens of other miraculous things it does for itself. But even such a living miracle sometimes needs help. It prods us to feed it by making us feel hungry. It reminds us to warm things up by making us shiver.
Most of the time, the weather is so comfortable that we hardly notice it. This is because the temperature is just right for the body. In order to carry on all its wondrous duties, it must be where things are not too hot and not too cold. Most o€ the time it can tune itself to slight changes in the weather. We feel comfortable until the temperature drops down low. Then we feel chilly because the body cannot keep itself as warm as it needs to be.
This is the time for us to think of a way to warm things up. We can turn up the furnace or crouch by the.fire, we can add a warm sweater or go for a frisky walk. The furnace and the fire make us comfortable again by warming the air around us. The extra sweater helps by holding the body's own heat close to the skin, so that cold air cannot steal it. The brisk walk, of course, is exercise. It warms us up because the moving muscles burn up sugary food and give off heat. Exercise is the body's own favorite way for keeping warm. And it has its own way of telling us about this.
When we feel chilly, suppose we do nothing at all to make things warmer. The body gets more uncomfortable and quite impatient. But unless we decide to act, it cannot turn up the furnace or add extra clothing by itself. It cannot move around unless we give permission. So it does the best it can. It starts exercising without moving around.
The brain sends signals along the nerve fibers. They tell the big muscles in the back, arms and legs to start moving even though they cannot go anywhere without permission. The muscles do the best they can. They start shivering and shaking. Now we feel really uncomfortable, though this is not the reason for it.
Those shivering muscles are really exercising. And when they exercise they burn up fuel and give off heat. True, this is not much exercise and it does not give off much heat. But shivering really does provide a little extra warmth for the body. What's more, it usually makes us feel so miserably uncomfortable that we decide to do something about it.
Sometimes all we can do is light a fire or turn up the furnace. Sometimes we can do the job better. This calls for two operations. First we wrap up in warm outdoor clothing. Then we go outside and enjoy a brisk walk or a peppy game, which is even better. This sort of exercise is just the thing to chase the shivers right out of a chilly day.