Description

Mammalian salivary glands are exocrine glands that produce saliva via a network of ducts. There are hundreds of minor salivary glands and three paired major salivary glands in humans (parotid, submandibular, and sublingual). There are three types of salivary glands: Serous, mucous, and seromucous (mixed). Alpha-amylase, an enzyme that converts starch into maltose and glucose, is the most common type of protein secreted in serous secretions. On the other hand, mucin, a lubricant, is the most common type of protein secreted in mucous secretions.

Every day, 1200 to 1500 milliliters of saliva are produced by humans. Parasympathetic stimulation is what causes salivation, or salivation; the active neurotransmitter, acetylcholine, binds to muscarinic receptors in the glands, which causes more salivation. The tubarial glands, the fourth pair of salivary glands discovered in 2020, are named for their position in front of and above the torus tubarius. However, there has been no confirmation of this one study's finding.

Sub-Maxillary Glands

The two parotid glands are major salivary glands that are wrapped around the mandibular ramus in humans. These are the largest of the salivary glands and secrete amylase to start the digestion of starches and saliva, as well as alpha-amylase, which is also known as ptyalin. They enter the oral cavity through the parotid duct. The glands are situated anterior to the temporal bone's mastoid process and posterior to the mandibular ramus. Because any iatrogenic lesion will result in either loss of action or strength of muscles involved in facial expression, they are clinically relevant in dissections of facial nerve branches while exposing the various lobes. They produce 20% of the total salivary content in the oral cavity. Mumps is a viral infection that is caused by infection in the parotid gland.

The submandibular glands, formerly known as the submaxillary glands, are a pair of major salivary glands that are located beneath the lower jaws, above the digastric muscles. The submandibular duct, also known as the Wharton duct, is where the secretion, which is a mixture of serous fluid and mucus, enters the oral cavity. The submandibular glands produce about it is two inches apart under the chin and about two fingers above the Adam's apple (laryngeal prominence). In the buccal, labial, and lingual mucosa, the soft palate, the lateral parts of the hard palate and the floor of the mouth or between muscle fibres of the tongue, there are approximately 800 to 1,000 minor salivary glands. They are between 1 and 2 millimeters in diameter, and in contrast to the major glands, they are only surrounded by connective tissue. A small lobule usually connects a number of acini in the gland. A minor salivary gland may have its own excretory duct or share an excretory duct with another gland. Their secretion is primarily mucous and serves a variety of purposes, including covering the oral cavity with saliva. If dry mouth is present, problems with dentures may be caused by malfunctioning minor salivary glands. The seventh cranial or facial nerve innervates the minor salivary glands.

Salivary Organ Hypo-function

A group of secretory cells is called an acinus. There are numerous acini within each lobule of the gland, with each acinus situated at the terminal portion of the gland connected to the ductal system. Each acinus is made up of a single layer of cuboidal epithelial cells that surround a lumen, which is the central opening where the secretory cells secrete saliva and deposit it. The three types of acini are categorized as serous, mucoserous and mucous based on the type of epithelial cell present and the secretory product produced. The lumina are formed by intercalated ducts in the duct system, which then join to form striated ducts. These drain into secretory ducts, also known as interlobar ducts, which are located between the lobes of the gland. Most major and minor glands have these, with the possible exception of the sublingual gland. The mouth is where all of a person's salivary glands end, where the saliva continues to aid in digestion. The acid that is present in the stomach quickly inactivates the released saliva, but saliva also contains enzymes that are actually activated by stomach acid.

Salivary organ brokenness alludes to one or the other xerostomia (the side effect of dry mouth) or salivary organ hypofunction (diminished creation of spit); a Cochrane review found that there was no strong evidence that topical therapies are effective in relieving the symptoms of dry mouth. Salivary gland dysfunction is a predictable side effect of radiotherapy of the head and neck region. Saliva production can be pharmacologically stimulated by sialagogues like pilocarpine and cevimeline. It can also be suppressed by so-called antisialagogues like tricyclic antidepress. Chemotherapy and radiation therapy, as well as surgical removal for benign or malignant lesions, may also impair function. Radiotherapy can cause permanent hypo salivation due to injury to the oral mucosa containing the salivary glands, resulting in xerostomia, whereas chemotherapy may only cause temporary salivary impairment.

Some species have their salivary glands modified to produce proteins; numerous species of birds and mammals, including humans, have salivary amylase. In addition, the venom glands of venomous snakes, Gila monsters and some shrews are actually modified salivary glands. In other organisms, such as insects, salivary glands are frequently utilized to produce proteins that are important to biology, such as silk or glues. Fly salivary glands, on the other hand, contain polytene chromosomes that have proven to be beneficial to genetic research.

Preganglionic nerves in the thoracic segments T1-T3 provide direct sympathetic innervation of the salivary glands. These nerves synapse with postganglionic neurons in the superior cervical ganglion to release norepinephrine, which is then received by 1-adrenergic receptors on the acinar and ductal cells of the salivary glands, resulting in an increase in cyclic adenosine monophosphatIt is important to keep in mind that in this regard, both parasympathetic and sympathetic stimuli result in an increase in salivary gland secretions. The difference lies in the composition of this saliva; once a sympathetic stimulus occurs, it primarily results in an increase in amilase secretion, which is produced by serous glands. In other words, both stimuli increase salivary gland secretions. The sympathetic nervous system also has an indirect effect on salivary gland secretions by innervating the blood vessels that supply the glands. This causes vasoconstriction by activating one adrenergic receptor, which reduces the amount of water in saliva.