saliva

Eva Rudolf-Müller is a freelance writer in the medical team. She studied human medicine and newspaper sciences and has repeatedly worked in both areas - as a doctor in the clinic, as a reviewer, and as a medical journalist for various specialist journals. She is currently working in online journalism, where a wide range of medicine is offered to everyone.

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Saliva is released into the oral cavity by glands in the lining of the cheek, palate and throat. It makes food bites slippery so that we can swallow them more easily. Saliva also contains digestive enzymes and is important for recognizing taste. Read all about saliva!

What is saliva

Saliva is the odorless and tasteless secretion of the salivary glands in the oral cavity. It is mainly formed by three large glands: the parotid gland (glandula parotis), which is also placed on both sides (sub-mandibular gland) and the sublingual gland (sublingual gland).

There are also numerous small salivary glands in the cheek, palate and throat mucosa as well as in the base of the tongue.

Saliva composition

The body produces around 0.5 to 1.5 liters of saliva per day. Composition of the secretion depends on the producing gland:

The parotid gland produces "dilution saliva", a thin, low-protein secretion that makes up about a quarter of the total amount of saliva.
The lower jaw salivary gland forms a clear, protein-containing and weakly stringy "gliding saliva", which makes up about two thirds of the amount of saliva produced daily.
The sublingual salivary gland supplies a protein-rich, stringy "gliding saliva".

One liter of saliva contains a total of 1.4 to 1.6 grams of protein as mucin in the form of mucoproteins (proteins with a carbohydrate content). Mucins form the mucous film on the wall of the oral cavity (as well as the esophagus, stomach and intestines).

The saliva also contains ammonia, uric acid and urea, some folic acid and vitamin C. It also contains electrolytes such as sodium and potassium.

Digestive enzymes are also found in saliva. The most important representative is alpha-amylase (ptyalin), which can break down carbohydrates (starch). It is produced and secreted almost exclusively by the parotid gland - in an amount sufficient to digest all of the starch ingested with food. There is not enough time for this because the food is swallowed relatively quickly (together with the enzyme). In the stomach, the salivary amylase is inactivated by the acidic gastric juice. The amylase from the pancreas then has to take care of the further breakdown of carbohydrates in the small intestine.

Another enzyme in saliva is fat-splitting lipase, which is secreted by the base of the tongue. This enzyme is of particular importance for infants, namely for the digestion of the fat contained in breast milk. This milk fat covers a large part of the energy needs of babies.

Secretion of saliva

The secretion of saliva is triggered reflexively by chemical irritation of the oral mucosa (contact with food) and by mechanical stimuli (chewing). Smell and taste stimuli (such as a good scent of roast meat or lemon), a feeling of hunger and psychogenic factors also trigger salivation.

When we sleep or are dehydrated, very little saliva is released.

What is the function of saliva?

Saliva has several tasks:

It is a solvent for nutrients that can only be recognized by the taste receptors in the tongue in a dissolved form.
Mucins, the "lubricants" of the oral cavity, make it easier to chew and swallow solid food components. In addition, the mucous film they form on the wall of the oral cavity protects the underlying cell layer (epithelium) from injury and dehydration.

It contains digestive enzymes such as fat-splitting lipase and carbohydrate-splitting ⍺-amylase.
Other enzymes contained are lysozyme and peroxidase. Lysozyme can break down wall components of bacteria; Peroxidase has unspecific antibacterial and antiviral properties.
Saliva also contains immunoglobulin A (IgA): this type of antibody can fight off pathogens.
Saliva moistens the oral cavity, which is important for clear pronunciation.
He keeps the mouth clean by constantly rinsing the oral cavity and teeth.

What saliva-related problems can I experience?

Acute inflammation of the parotid gland (parotitis) is caused by viruses or bacteria. The mumps virus is a common cause of painfully swollen parotid glands. However, parotitis can always recur, i.e. it can occur chronically and recurrently. The cause has not yet been finally clarified.

A tumor can develop in the area of the salivary glands. Such a salivary gland tumor can be benign or malignant (cancer).

If the composition of the saliva changes as a result of illness or medication, a salivary stone can form - a hard concrement made up of components of the glandular secretion. Salivary stones can clog the duct of a salivary gland, causing the gland to swell.

Salivary cysts can be congenital enlargements of the glands or result from the accumulation of saliva due to a stone.

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