Saliva and Salivary Glands: Facts and Health Problems

Updated on October 20, 2017
AliciaC profile image

Linda Crampton is a teacher with a first class honors degree in biology. She writes about human biology and the scientific basis of disease.

Holding the mouth open for a long time can cause a dry mouth as water from saliva evaporates. (This crocodile is gaping to cool him or herself down.)
Holding the mouth open for a long time can cause a dry mouth as water from saliva evaporates. (This crocodile is gaping to cool him or herself down.) | Source

A Very Useful Liquid

Saliva is the watery liquid in our mouths. It has important functions, including destroying bacteria, helping to prevent tooth decay, beginning the digestion of food, helpIng us to speak, and enabling us to swallow food. Problems with saliva production can interfere with our lives. One of these problems is Sjogren's syndrome, a condition in which the salivary glands make an insufficient amount of saliva.

Saliva contains many chemicals in addition to water, including mucus, salts, antibacterial substances, enzymes, and chemicals that control the pH in the mouth. It also contains bacterial cells, since bacteria live in our mouths, as well as human cells shed by the lining of the mouth, the tongue, and the gums.

The salivary glands continuously release their secretion into the mouth, although the amount varies during the day. The quantity of saliva increases when we taste, smell, or even think of food. It decreases when we go to sleep.

The major salivary glands
The major salivary glands | Source

The parotid glands are located on the insides of the cheeks, the submandibular glands are found under the floor of the mouth, and the sublingual glands are situated under the tongue. In addition, there are between six hundred and a thousand minor salivary glands located in the mouth, throat, and lips.

Composition of Saliva

  • Saliva is a thick, colorless, and glistening liquid consisting of about 98% to 99% water. Mucus produces the glistening appearance and causes the liquid to have a thicker texture than pure water. Saliva also contains enzymes and other proteins, as well as salts and buffering agents to keep the pH at the correct level.
  • The water in saliva is obtained from blood. The water leaves the capillaries in the salivary glands to become part of the saliva.
  • Saliva contains an enzyme called salivary amylase or ptyalin, which digests starch into a sugar called maltose. (Maltose is later broken up into glucose molecules in the small intestine.) If we chew a starchy food like a piece of bread or a cracker for a long time, it will start to taste sweet as the starch molecules break up into maltose molecules.
  • Saliva also contains chemicals that fight bacteria, including lysozyme, lactoferrin, peroxidase, and immunoglobulin A.
  • Sodium bicarbonate in saliva helps to neutralize acids in foods and drinks. These acids can damage tooth enamel.

Cranberries are acidic. Their juice stimulates saliva flow.
Cranberries are acidic. Their juice stimulates saliva flow. | Source

More Facts About Saliva

  • Saliva keeps the mouth moist and comfortable and lubricates food so that it's easy to swallow. It also prevents the swallowed food, or bolus, from damaging the wall of the esophagus.
  • The moisture in the mouth helps us to manipulate the tongue and lips to make speech sounds.
  • Saliva also moistens food and enables us to taste it.
  • Saliva reduces tooth decay and infection in the mouth by washing away food particles, bacteria, and dead cells.
  • We make much less saliva when we sleep than when we are awake. This allows bacteria to build up and can cause bad breath in the morning.
  • Saliva helps us to maintain the correct amount of water in our bodies. When we become dehydrated, less saliva is made and the mouth becomes drier. This stimulates us to drink.

A stained slide showing parotid gland cells; the lighter cells are part of a duct
A stained slide showing parotid gland cells; the lighter cells are part of a duct | Source

The salivary glands generally make between one and two liters of liquid a day (between two and four pints). During an average lifetime they produce about 10,000 gallons of saliva.

Salivary Glands

  • The parotid glands are the largest salivary glands. One gland is located in each cheek, in front of the ear.
  • The two submandibular or submaxilary glands are located under the floor of the mouth.
  • The two sublingual glands are located under the tongue, in front of the submandibular glands.
  • The parotid glands produce a watery liquid containing proteins.
  • The submandibular glands produce a liquid that is a mixture of water and mucus.
  • The sublingual glands produce a liquid that contains more mucus than the secretions of the other salivary glands.
  • Saliva leaves the glands in tubes called salivary ducts.
  • More saliva is made when the mouth contains spicy, sour, or acidic foods. When taste buds are stimulated by these chemicals they trigger the release of saliva.

What Are Salivary Gland Stones?

Stones in a Salivary Gland or Duct

Salivary glands and ducts may contain "stones". These are small, solid lumps made from crystallized chemicals in the saliva. Most stones contain calcium and form in the submandibular glands or ducts.

Stones in a duct can block the duct and cause saliva to build up behind the blockage. This can result in swelling and pain, especially when a person is trying to open their mouth or swallow. The pain may begin suddenly just after a person has begun to eat and may be intense. The swelling may extend over the face and even down into the neck. The mouth may be dry and the area may become infected as well. Symptoms of a stone will probably be less severe if the stone stays in the salivary gland and doesn't enter the duct or if it only partially blocks the duct.

The cause of salivary gland stones isn't known for certain, but thickened saliva is believed to increase the risk. It's important to stay well hydrated, which may reduce the chance of stone formation.

Crystallized saliva
Crystallized saliva | Source

Possible Treatments

Drinking a lot of water may help to remove a stone. A warm compress or a gentle massage may also help. Sucking on a small piece of lemon will stimulate saliva flow and may help to remove a stone if it isn't very large. However, increased saliva flow in a blocked salivary duct that stays blocked may worsen the pain. A doctor or dentist may be able to remove a stone inside their office. Surgical techniques can also remove the stone.

What Is Sjogren's Syndrome?

Sjogren's syndrome usually affects women over the age of forty, but it may also affect men and younger people—even children.

Sjogren's Syndrome: An Autoimmune Disease

Our immune system normally fights bacteria and viruses. In an autoimmune disease the immune system mistakenly attacks the body's own cells instead. Sjogren's syndrome is an autoimmune disease in which the glands that produce saliva and tears are attacked by the immune system. The glands become inflamed and don't produce enough liquid. As a result, the person has dry eyes and a dry mouth.

A dry mouth is technically known as xerostomia. Besides being uncomfortable, xerostomia can lead to increased tooth decay and an increased risk of gum disease, bacterial infections, yeast infections, and bad breath. Dry mouth isn't necessarily a sign of Sjogren's syndrome, however. Many medications can cause a dry mouth, and so can other illnesses, such as fibromyalgia.

In primary Sjogren's syndrome only the eyes and mouth are affected. In secondary Sjogren's syndrome a person also experiences other health problems, such as painful and swollen joints. Organs such as the lungs, digestive organs, and kidneys may also be affected. The patient may be diagnosed with another autoimmune disease in addition to Sjogren's syndrome, such as rheumatoid arthritis, lupus, or scleroderma.

Lemons are acidic and stimulate saliva flow, but lemon juice can damage tooth enamel.
Lemons are acidic and stimulate saliva flow, but lemon juice can damage tooth enamel. | Source

Someone who may have or has Sjogren's syndrome should visit a doctor for a diagnosis and treatment recommendations. Other saliva or gland problems should also be checked by a doctor if they persist. These problems include a change in saliva texture or pain that may be coming from a salivary gland or duct.

Relieving the Discomfort

A doctor and a dentist should be consulted about the best treatments for Sjogren's syndrome. The doctor may prescribe specific medications and will probably suggest other helpful steps to relieve symptoms. Sucking sugarless candies or chewing sugarless gum may be recommended because they can stimulate saliva flow and decrease dry mouth symptoms. Someone with a dry mouth should drink lots of water, preferably in frequent sips.

Drinking dilute lemon juice or sucking a small slice of lemon may increase saliva flow temporarily. Lemon juice is acidic and can damage tooth enamel, though. Concentrated lemon juice may cause rapid saliva release followed by an even drier mouth than before.

The choice of toothpaste and mouthwash is important for someone with Sjogren's syndrome. Some products are less drying than others. Some manufacturers claim that their products actually help a dry mouth.

Cave Swiftlets and Saliva

Saliva and Bird's Nest Soup

Many other animals have saliva and salivary glands, although sometimes the glands are modified for a particular function, such as producing venom. The saliva of some animals has an interesting feature not shared by the human version. In the case of cave swiftlets, the different feature is useful to us.

Cave swiftlets roost in dark caves, where they navigate by echolocation. During the day the birds hunt for insects outside the caves. They produce a protein-rich and sticky saliva which helps them build their nests. The saliva is used to stick nest materials together. It's a gummy substance and hardens when exposed to air.

The hardened saliva is the basis for bird's nest soup, which is popular in Asia and is thought to have many health benefits by the local people. The soup is very expensive. The nest is washed before use to remove unwanted material and has a gelatinous texture when added to water. It's often cooked in chicken broth to give it taste.

Bird's nest soup is made from dried bird saliva.
Bird's nest soup is made from dried bird saliva. | Source

The Cycle of Saliva Production and Removal

Most of us rarely think about our saliva unless a problem arises. The cycle of saliva secretion into our oral cavity followed by the act of swallowing to remove it takes place continuously throughout the day. It's interesting that the liquid has so many functions in our lives. It's possible that there are even more that we haven't yet discovered.


Salivary glands and saliva information from Colorado State University

Facts about salivary glands and potential problems from the American Academy of Otolaryngology - Head and Neck Surgery

Information about salivary gland stones from WebMD

Sjogren's syndrome facts from the U.S. National Library of Medicine

Sjogren's syndrome causes, symptoms, and treatments from the Mayo Clinic

How bird's nest soup is made from Business Insider

© 2012 Linda Crampton


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    • AliciaC profile image

      Linda Crampton 14 months ago from British Columbia, Canada

      Hi, Emmanuel. No, saliva isn't made from blood cells. The liquid in saliva comes from the capillaries in the salivary glands. Water and some chemicals leave the capillaries and become part of the saliva, but the blood cells are too large to leave. Saliva does pick up some cells when it enters the mouth cavity, though.

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      Emmanuel 14 months ago

      I will like to know if the saliva glands make saliva from d red & white blood cells?

    • AliciaC profile image

      Linda Crampton 2 years ago from British Columbia, Canada

      You're welcome, slushy.

    • profile image

      slushy 2 years ago

      the info is super for homework thanks! :)

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you for the comment, Faffeinez!

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      Faffeinez 4 years ago

      Informative and interesting! Keep it up !! :)

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      I'm glad my hub helped you with your homework. Thanks for noticing the typo, which I'll edit.

    • profile image

      PieAssassin432 4 years ago

      Hey, thanks for the awesome post about saliva. It worked great for a homework assignment.

      On a side note, I think you misspelled "moist" in the sentence, "Saliva keeps the mouth most and comfortable…."

      Other than that, great post.

    • AliciaC profile image

      Linda Crampton 5 years ago from British Columbia, Canada

      Thank you for the comment, pinkhawk. I appreciate it!

    • pinkhawk profile image

      pinkhawk 5 years ago from Pearl of the Orient

      These info are new to me, thank you for posting or sharing! Great hub! ^_^

    • AliciaC profile image

      Linda Crampton 5 years ago from British Columbia, Canada

      Thank you for the comment, ignugent17. Yes, saliva is a very helpful substance! It does many things for us.

    • profile image

      ignugent17 5 years ago

      This is very interesting! I did not know that saliva is very useful to our body. Thanks for sharing the information.

    • AliciaC profile image

      Linda Crampton 5 years ago from British Columbia, Canada

      There are many possible reasons for excessive saliva production, pranaya kumar mondal. It's important that you visit your doctor to discover the cause of your problem and to find a treatment.

    • profile image

      pranaya kumar mondal 5 years ago

      reason behind more release of saliva, how to cure that problem.

    • AliciaC profile image

      Linda Crampton 5 years ago from British Columbia, Canada

      Thank you, teaches! I appreciate your comment and your support very much.

    • teaches12345 profile image

      Dianna Mendez 5 years ago

      I didn't think the subject of saliva cold be so interesting. I learned much from reading through your hub. Well, I am glad that is so beneficial in breaking down food acids that may harm our enamel. Voted up and it so deserves it!

    • AliciaC profile image

      Linda Crampton 5 years ago from British Columbia, Canada

      Thank you, drbj. Saliva is a substance that many people take for granted, but it's actually very useful. Like you, I wouldn't like to eat bird's nest soup, though!

    • drbj profile image

      drbj and sherry 5 years ago from south Florida

      Sakes alive-a, so much new information about saliva!

      Thanks, Alicia, for providing this consummate compendium of saliva facts. Now I know why birdsnest soup never held any attraction for me.

      Excellent research, m'dear.

    • AliciaC profile image

      Linda Crampton 5 years ago from British Columbia, Canada

      Thank you very much, unknown spy! I appreciate your visit and comment.

    • unknown spy profile image

      IAmForbidden 5 years ago from Neverland - where children never grow up.

      Wow, you covered this topic very well Alicia! your article is the most detailed one, great work providing this info to us!

    • AliciaC profile image

      Linda Crampton 5 years ago from British Columbia, Canada

      Thank you for the visit, Tom. I appreciate the share very much, as well as the comment and the votes!

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      Thomas Silvia 5 years ago from Massachusetts

      Hi Alicia great well written and very informative hub, this information was so very interesting and some of it i did not know before reading this hub, thanks for helping me learn more about this subject !

      Vote up and more !!! SHARING !