There are few fluids as off-putting as saliva. Not only is being spit upon an insult in cultures all across the world; even our own saliva is gross to us if it doesn’t stay in our mouths where it belongs. Despite its lowly reputation, however, saliva plays a vital role in our daily lives. From helping us digest food to maintaining our oral health, saliva has an enormous number of functions. Produced by glands located at the back of our mouths, saliva contains enzymes, hormones, antibodies, electrolytes, and minerals that help us digest food, lubricate our mouth, cleanse our teeth, and protect our body from harmful bacteria. There are several reasons why saliva is important. First, it provides lubrication during chewing, and helps us taste our food. Second, it aids in digestion by breaking down food into smaller particles. Third, it prevents bacteria from building up on teeth. Finally, it aids in the formation of bones and teeth.
1. Saliva is a natural lubricant that helps protect our teeth from damage. When we eat, drink, or chew gum, we swallow air into our mouth along with the liquid. This causes the liquid to expand and push against the back of our tongue, causing it to swell. As this swelling continues, the muscles around the opening of the salivary ducts contract, squeezing the liquid out through the ducts.
2. Saliva helps us taste foods and beverages. When you eat or drink something sweet, your body releases a chemical called amylase. Amylase breaks down starch molecules found in sugar and other carbohydrates. The resulting mixture of glucose and maltose then travels from the mouth to the stomach where it is absorbed into the bloodstream.
3. Saliva helps break down food both mechanically and chemically. This gives our digestive system a headstart in turning food into usable energy. Saliva contains enzymes that help break down food and aid digestion. Saliva contains many different kinds of enzymes including amylase, lipase, proteases, and others. These enzymes are present in saliva at concentrations ranging from 0.01 mg/mL to 1.0 mg/mL. Amylase is an enzyme that breaks down starch in foods like bread and potatoes into simple sugars. Lipase is an enzyme that digests fat-rich foods like butter and cheese. Protease is an enzyme that degrades protein. This begins digestion of protein-rich foods like meat and eggs. Other enzymes include urease, lactate dehydrogenase, and phosphatase. Urease is an enzyme that converts urea into ammonia. Lactate dehydrogenase is an enzyme that oxidizes lactic acid into pyruvic acid. Phosphatase is an enzyme that hydrolyzes phosphate esters.
4. Saliva helps prevent tooth decay. The first line of defense against tooth decay is saliva. When we chew our food, we produce saliva, which contains enzymes that help break down the sugar molecules in foods. These enzymes work together with bacteria present in the mouth to neutralize harmful substances. If these harmful substances enter the bloodstream, they may cause damage to the body. Saliva plays a role in maintaining oral hygiene by mechanically washing away bacteria and debris from between our teeth, but also the nasal passages. When we talk about salivary glands, we refer to two different types of glands. One type produces saliva while the other produces mucus. Mucus is produced from the serous membranes lining the mouth cavity. The nose is lined with mucus membranes that trap dust, bacteria, viruses, allergens, and pollutants. The mucus membranes are constantly being renewed by cells called cilia. Cilia move toward the back of the nose where they sweep away particles. They then send signals to the brain indicating that something is present in the air.
5. Saliva aids in the formation of bones and teeth. The components in saliva have been found to help in the remineralization of teeth, allowing you to restore the health of your teeth by repairing the enamel over time. When the enamel surface is exposed to acid, the mineral content is lost. To restore the enamel, saliva neutralizes the acidic environment and promotes the precipitation of calcium and phosphate ions onto the enamel surface.
What a great number of jobs for such a humble substance as saliva! Hopefully we can all appreciate the critical importance of this simple-seeming fluid. Although it may be gross to think about for any length of time, it would do us all well to recognize the value of our saliva.