People are seldom much aware of this fluid in their daily lives, and people do not generally consider whether or not it is secreted, nor in what quantities. Saliva is believed to be a very simple fluid, when in fact it is a most special compound, containing specific levels of various chemicals.
First of all, saliva permits you to taste your food. The flavor-giving molecules in food dissolve in saliva and combine with the taste-receptor nerve endings on your tongue. Only in this way can you actually taste what you are eating. That’s also the reason why you cannot taste food when your mouth is dry.
Saliva is secreted by three different glands, and makes it easier to swallow food by moistening it, as well as containing chemical substances that dissolve what we eat into particles of benefit to the body. In the saliva itself are two different fluids with very different properties. One thoroughly breaks down carbohydrates and turns them partially into sugar. For example, if you place a piece of bread—a carbohydrate—in your mouth and wait for a minute, you will taste the sugar of the broken-down carbohydrate. The other saliva fluid is very dense. Thanks to this liquid’s stickiness, the particles of food that spread around the mouth as we chew are brought together in a kind of paste.
If saliva were not secreted, our food would be too dry for us to swallow, and we could neither swallow it, nor speak properly. We would be unable to consume any solids, and would have to feed ourselves solely on liquids—which would make life rather difficult.
Our mouths work just like chemical laboratories in breaking down the starch in what we eat. The enzyme known as ptyalin in saliva is especially produced for this purpose, to break down the starch and turn it into sugar.
The digestion taking place in the mouth is not only chemical. Mechanical digestion is also performed by the teeth. These two forms of digestion complement each other.
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