Salivary Glands  

Salivary glands are structures attached to the human digestive system. They are located in the oral cavity and are responsible for the production of saliva.

They are classified as exocrine glands, with the function of secreting saliva.

Saliva is important for starting the digestion process. It softens food so that it can enter the digestive tract, lubricates food particles, acts as an antibiotic and eliminates some germs.

Saliva in Digestion 

You may have heard that digestion of food begins in the mouth. This statement is made because saliva plays a key role in food processing. The salivary glands are responsible for the production and release of salivary flow in the oral cavity.

Humans, like other animals, have organs called salivary glands, which are located at the beginning of the digestive tract. Three main pairs of salivary glands are present:

- Parotid glands: they are the largest, located in front of the ear pinna, being responsible for producing a large part of the saliva we need. It has lymph nodes inside and is closely related to the facial nerve, responsible for moving the muscles of the face;

- Submandibular glands: they are found below the mandible, with a superficial portion and a deep portion to the mylohyoid muscle, presenting a single channel for saliva drainage to the mouth (as it happens in the parotid gland);

- Sublingual glands: located just under the tongue, also found in pairs (as well as parotid and submandibular glands, composing with these the group of major salivary glands). It produces saliva in smaller quantities than the others, but it has an important role in the beginning of the digestive process. It differs from the previous ones in that it has multiple salivary ducts that drain saliva to the floor of the mouth;

- Minor salivary glands: distributed below the mucosa of the mouth and pharynx, mainly on the palate, inner region of the cheek, floor and pharynx, they complement the saliva production function, being important in the lubrication of the food bolus, helping in chewing and swallowing.

Functions of the Salivary Glands in Digestion 

Salivary glands are structures responsible for producing and secreting saliva. They do this all the time, keeping the oral cavity moist. They also release this flow when there are stimuli (visual, auditory, memory) and while we are eating, to start the digestive process.

Saliva has more than one function in the human body. It keeps the mucous membranes of the upper aerodigestive tract hydrated, ensuring its vitality and protection. It has a direct action on the continuous process of mineralization and demineralization of teeth, so it also influences their health.

When we maintain a good salivary flow, we also guarantee a natural hygiene of the mouth. And we cannot forget that when it is properly balanced, it has the function of maintaining the stability of the oral pH, preventing problems such as cavities and dental erosion.

In addition to all this, we explain that saliva contributes to the process of food digestion. It presents a series of enzymes that start, still in the mouth, the chemical process of digestion. The main one is ptyalin or salivary amylase, responsible for the digestion of starch. There are other enzymes in saliva, as well as a large amount of mineral salts, the most abundant being calcium.

Histology

Salivary glands are made up of clustered grains called acini. From them, branched ducts depart that release saliva to the various points spread throughout the oral cavity.

The salivary gland consists of acini, tubular system and excretory ducts.

There are also two types of secretory cells: serous cells and mucous cells.

Serous cells are pyramidal in shape. They produce proteins and glycoproteins, in general, with enzymatic and antimicrobial activities. In addition, they also secrete water, ions, enzymes and glycoproteins.

The parotid glands are predominantly composed of serous cells.

Mucous cells generally have a tubular shape and are characteristic for accumulating large amounts of mucus. This condition even compresses the cell's organelles and nucleus. The main product of mucous cells is mucins.

Both serous and mucous cells can be found in the sublingual and submaxillary glands.

What problems can affect the salivary glands?

All salivary glands can develop diseases. One of the most common problems is calculus, small stones that form in these structures due to the accumulation of minerals. This problem is called sialolithiasis.

When there is an imbalance in the composition of saliva, or its flow is impaired by dehydration, for example, mineral particles aggregate, giving rise to small stones, which can obstruct the salivary duct and prevent saliva from being secreted into the mouth.

As a result of the obstruction, the salivary gland can become inflamed, a condition that is also triggered by infection with viruses or bacteria (called sialadenitis). In addition to sialolithiasis, this structure can be impaired by autoimmune diseases, such as Sjögren's Syndrome, an immune system disorder that causes dry mouth and swelling of the salivary glands.

We can also notice the appearance of nodules in the salivary glands, which need to be properly evaluated to determine their nature and the need for specific treatment.

To ensure that they always remain healthy, the ideal is to adopt good habits, maintaining a balanced diet, avoiding tobacco, taking care of oral hygiene and ingesting plenty of water. After all, this is the main ingredient used by them to produce saliva.

The salivary glands are responsible for producing saliva, ensuring the health of the oral cavity and, indirectly, a good digestion of food. Therefore, if you notice any change in these structures or any discomfort, look for a Head and Neck Surgeon to be evaluated by a specialist.

Illnesses

Some diseases may be associated with the salivary glands.

The most common symptoms are: swelling of the gland, local pain, reddened skin and changes in saliva composition.

Bacteria and viruses can infect the salivary glands. Some associated diseases are:

Mumps: viral infection that affects the parotid glands.

Sialadenitis: inflammation of the salivary gland resulting from the presence of bacteria or viruses.

Parotitis: inflammation of the parotid glands due to the presence of a virus.

Tumors: Some tumors can form in the salivary glands and lead to cancer.