Saliva enzymes, the breakdown of nutrients and its disruption when the enzymatic composition of saliva changes

For a person, the need to eat is due to the fact that all cells of the body are synthesized from products, energy is generated for vital processes. To fulfill these functions, any food must undergo a chemical treatment in the digestive tract. Initially, food enters the oral cavity, where it is broken down by enzymes or biological catalysts in saliva.

Being the initial link in the digestion process, salivary fluid is of great importance for quality assimilation of necessary substances and for the formation of energy fuel and constituent parts of the cell from them. In the oral cavity, the stage of separation of complex proteins, fats and carbohydrates into smaller parts is started, and then gradually, by the action of saliva enzymes, they are broken down into molecules.

The Need for Saliva for Digestion: Functions

Without pretreatment with salivary enzymes, the digestibility of food particles is significantly reduced and the absorption of essential trace elements in the entire digestive tract worsens. Therefore, saliva is an indispensable component in the breakdown of complex nutritional links into small components (for example, polysaccharides into carbohydrates). Constant insufficient saliva processing of the food lump during meals can provoke diseases of the gastrointestinal tract - gastritis, colitis, constipation.

Saliva performs several important functions that are directly or indirectly involved in the digestive process:

1. With the help of salivary fluid, the process of separation of complex carbohydrates begins in the oral cavity. These include starch (all flour products, pasta, baked goods, white bread) and glycogen (sugar, chocolate, honey, dried fruits).
2. Protects the mucous membrane of the mouth from injury (with the help of mucus - mucin) and infectious lesions (thanks to lysozyme, which has antiseptic properties).
3. Supports hard tooth tissues (dentine, enamel) in a healthy state, feeding them with compounds of fluoride and calcium, which are found in saliva.
4. In a small amount, it removes harmful waste products from the body - urea, ammonia, lead salts, mercury.

Features of the composition

Most of the salivary fluid (98.5-99%) is water. Its presence ensures the connection of various elements with each other and the ability of them to interact with each other.

In the aqueous part, various salts are dissolved, represented by the ions of potassium, sodium, magnesium and calcium. This composition ensures the mineralization of the hard tissues of the tooth (dentin and enamel), the preservation of their strength, resistance to stress when chewing food.

The remaining 1-1.5% are represented by the organic part:

1. Mucin - a complex of glycoproteins, has the appearance of a mucous substance, participates in the gluing of the food lump and contributes to its unhindered movement along the esophagus towards the stomach.
2. Lysozyme - a bactericidal enzyme that destroys the wall of pathogens. It acts in the oral cavity as an antiseptic, preventing the development of infectious diseases on the gums, mucous membranes, blocks the movement of microbes through the digestive tract.
3. Various enzymes - under their influence, the breakdown of nutrients in the oral cavity occurs.
4. Nitrogen compounds (ammonia, urea, creatine), partially removed from the internal environment of the body through saliva to the outside.
5. Proteins (albumins, globulins) and free amino acids - perform protective and binding functions, wetting the mucous membrane and preventing it from drying out and the formation of damage.

How the formation and secretion of saliva occurs: disturbances and changes in the process

Enzymes and mucous secretions of saliva are formed in large salivary glands. In humans, there are three pairs of them in the body:

• parotid - located between the zygomatic arch and the ears;
• the submandibulars are adjacent to the inner part of the lower jaw;
• sublinguals are located in the thickness of the soft tissues under the tongue.

Each of them has a large duct that opens into the oral cavity.

The large salivary glands are made up of epithelial cells called glandulocytes. The latter produce an enzymatic liquid inside themselves and bring it out through small holes in their wall. Gradually accumulating enzyme from the thickness of the salivary gland enters the duct and pours out into the oral cavity.

The work of the large salivary glands is influenced by the center of salivation, located in humans in the medulla oblongata. Saliva production increases with food intake and the sight or smell of appetite-inducing food. The production of salivary fluid decreases in stressful situations, with fright, fear. The secretion of saliva during sleep almost completely stops.

In the thickness of the oral mucosa, there are also many small salivary glands. They have a small size (1-2 mm) and a small diameter excretory duct. Their function is the constant secretion of mucus in small quantities.

Normally, 1.5-2 liters of saliva are released per day, a violation of this process can occur for various reasons. There are 2 main groups of pathologies.

Hyposalivation

Hyposalivation - decrease in daily saliva production, while its amount is reduced to 0.5 liters per day or less. This condition leads to a deterioration in the wetting of the food lump, makes it difficult to swallow, and disrupts the absorption of nutrients. Appears dry mouth, cracks in the mucous membrane, accession of infections and suppuration. Arises bad breath, speech and pronunciation of sounds deteriorate.

Hyposalivation can be caused by the following diseases:

• diabetes mellitus - there is a sharp decrease in the water part of the salivary fluid;
• Sjogren's syndrome - a disease of the immune system, leading to the degeneration of the tissue of the salivary glands;
• blockage of the duct of the large salivary gland with a stone - is formed when the mineral composition of saliva is disturbed, with an increased content of calcium salts in it;
• stress and neurosis - hyposalivation is of a reflex nature;
• chemotherapy and radiation for cancer;
• diseases of the gastrointestinal tract.

Hypersalivation

Hypersalivation - increase in daily saliva production up to 2.5 liters or more per day. By itself, this condition does not bring harm, but it is a symptom of pathology in the body:

• inflammatory disease in the oral cavity - abscesses, phlegmon, stomatitis, gingivitis, angina;
• diseases of the nervous system - cerebral palsy, Parkinson's disease.

Salivary fluid enzymes

Saliva enzymes found in the oral cavity:

1. Amylase (ptyalin) - breaks down complex carbohydrates starch and glycogen to monosaccharides. Consists of an organic part, calcium and chlorine molecules.
2. Maltase - breaks down maltose (a polysaccharide found in white and black bread, baked goods, pasta) to simple carbohydrates.
3. Lysozyme - dissolves the cytoplasmic membrane that is part of the bacterial wall. Consists of several protein particles bound by sulfur molecules.
4. Lipase - begins in the oral cavity the process of decomposition of complex fats into simple ones, it is produced in small quantities.
5. Peroxidase - oxidize hydrogen peroxide molecules, which allows you to maintain normal microflora in the mouth.
6. Carbonic anhydrase - participates in the decomposition of carbonic acid to carbon dioxide and water.
7. Proteinases - are produced in extremely small quantities. They begin to work after food enters the stomach and intestines, participating in the digestion of proteins.

Violations of the enzyme composition and properties of saliva, consequences

The enzymes in saliva work in a slightly alkaline environment. The presence of diseases of the dentition (dental plaque, multiple caries, gingivitis, periodontitis) provoke a change to a slightly acidic environment. The beginning of the process of digesting starch and maltose stops. As a result, bread, pastries, pasta form lumps in the digestive tract, causing constipation.

After some diseases of the large salivary glands (mumps, sialoadenitis, Sjogren's disease) epithelial cells producing enzymes are replaced by cicatricial connective tissue. This condition leads to a sharp decrease in all components of saliva, which negatively affects the digestion and absorption of nutrients.

Being the initial stage in the process of digestion and having in its composition many different enzymes, saliva is of exceptional importance for the normal functioning of the human body.

Various pathologies of the composition and properties of salivary fluid can have many causes, both local (blockage of the duct with a stone, gingivitis) and general (diseases of the nervous system) nature. Only a qualified specialist should deal with the treatment of these diseases.