Salivary glands: structure, functions and diseases

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The salivary glands are glands that produce saliva and perform a number of important functions in the body. Did you know that they work non-stop and can produce about a liter of saliva in one day? Find out what the types of salivary glands are, how they are built and what their key task is in the human body.

Salivary glands – characteristics

The salivary glands (salivary glands) are the organs of external secretion. They consist of three pairs of large glands and small, numerous, scattered throughout the oral and pharyngeal mucosa. These glands are responsible for the continuous production of saliva in the body. The salivary gland consists of the parenchyma, where the secretory cells produce saliva, and the ducts that lead out saliva.

The 3 main, large salivary glands are:

1. parotid glands – these are the largest salivary glands with a mass of about 30-40 g. They are located symmetrically on both sides of the face. The salivary gland produces mainly serous content. Saliva flows from the parotid gland into the vestibule of the mouth. This salivary gland produces about 25% of resting saliva and 70% of stimulated saliva. The external carotid artery, the behind the mandibular vein and the facial nerve run through the parenchyma of the parotid gland. There are also lymph nodes and vessels in the salivary gland.
2. submandibular glands – these are two glands located on both sides of the face in the so-called submandibular triangles (in the lower part of the mandible). The mouth of this salivary gland is under the tongue. The submandibular gland produces about 70% of the saliva in the resting state and 25% of the saliva when stimulated.
3. Sublingual salivary glands – are the smallest of the large salivary glands. They are located in the floor of the mouth on the muscle, just below the mucosa. It drains saliva to the floor of the mouth, similar to the submandibular glands.

Salivary glands – role and functions

The most important role of the salivary glands is the secretion of saliva, which has many functions in the mouth and throat.

The main components of saliva are:

1. water – 99,5%,
2. digestive enzymes, e.g. salivary amylase, which initially breaks down sugars,
3. bactericidal substances (lysozyme, lactoferrin, sialoperoxidase system) – reduce the growth of bacteria in the mouth and throat, protecting against their harmful effects on the entire body,
4. carbonate and phosphate ions – responsible for maintaining the correct pH in the oral cavity. They are the guardian of the internal environment,
5. calcium ions and phosphates – important for balancing the processes of demineralization and remineralization, key in the formation of caries.

The composition of saliva varies depending on the response to stimuli. For example, saliva will have a different composition at the time of rest, and a different composition at the time of chewing or tasting food.

Saliva has many functions:

1. the production of digestive enzymes that are used to pre-digest food.
2. saliva moisturizes the food billets and dissolves them, making them easier to swallow.
3. maintains an appropriate pH in the oral cavity,
4. has a bactericidal effect,
5. prevents tooth decay,
6. moisturizes the inside of the mouth and throat.

Salivary glands – diseases

The most common disease processes are the 3 large glands.

The following factors contribute to the abnormalities in the functioning of these glands:

1. salivary gland stones,
2. anxiety,
3. necrotic metaplasia of the salivary glands,
4. tumors.

Salivary glands – urolithiasis

Salivary gland stones are a disease with non-inflammatory factors. It is the deposition of mineral salts in the salivary glands, which leads to the formation of salivary stones. When the stones are smaller, they obstruct the flow of saliva, and the larger ones completely block the path of salivary flow from the salivary gland. Most often, salivary gland stones affect the submandibular glands. The disease manifests itself as an enlarged salivary gland and pain, especially when eating. The complication is infection of the salivary gland and inflammation.

The non-inflammatory conditions in the salivary gland are also influenced by other factors, such as: hormonal disorders, disorders of the metabolism and the autonomic system.

Other non-inflammatory diseases of the salivary glands are pathological conditions resulting from abnormal hormonal balance and metabolism disorders. In such cases, there is enlargement of the salivary glands, pain, and disturbances in salivation (too much or too little saliva).

Salivary glands – Sjögren’s syndrome

Sjögren’s syndrome is a disease of unclear origin. It belongs to the group of autoimmune diseases. It consists in the gradual disappearance of the secretory function of the glands. It occurs alone or in the course of other diseases (e.g. rheumatoid arthritis, systemic lupus erythematosus). The main symptoms are dry mouth (xerostomia) and dry conjunctiva. The disease affects women more often.

Salivary glands – tumors

Tumors of the salivary glands constitute a separate group of diseases due to their complexity and diversity. Most often, cancer cells are located in the large salivary glands. Both benign and malignant neoplasms are detected in the salivary glands. Usually they are: tumor mixtus, mucocutaneous carcinoma, adenocystic carcinoma (so-called oblast).

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