Where and why is saliva secreted?
Salivary glands are never absent inside our mouths. Especially when we see a fruit or something similar that we crave, the area under our tongue turns into a reservoir of saliva. Saliva is produced and secreted by special glands located around the oral cavity.
What are the names of the salivary glands?
There are many glands whose function is to secrete saliva. Three of them are particularly important. These are lined up one after the other on the sides of our jaw. They are the parotid (sub-ear), submandibular (sub-jaw), and sublingual (sub-tongue) glands.
Where are the salivary glands located?
Their placement can be more or less understood from their names. The Parotid (Greek, *para* = near, *ous* [a derivative of *otis*] = ear) got its name because it is located in the region below the ear. The submandibular and sublingual glands are also found in the region from which they take their names, namely under the lower jaw and under the tongue.
What is the structure of the salivary glands?
The salivary glands are shaped like bunches of grapes and are formed by groups of small, berry-like vesicles (acini).
Each vesicle is connected to the oral cavity by a narrow, short duct that serves to discharge the saliva produced. The secretion of these glands has slightly different chemical structures.
What is salivary secretion?
The salivary glands work continuously. Their activity does not stop even during sleep. Saliva is secreted when food is taken into the mouth. Often, the mouth waters when one sees or even thinks about food (conditioned reflex). This watering increases saliva production. Calculations have shown that the average amount of saliva secreted in 24 hours is between 200–400 grams.
What is the composition of saliva?
Saliva, which is colorless and sticky, is composed of $99.42\%$ water, $0.22\%$ mucin, and $0.22\%$ mineral salts (potassium chloride, potassium phosphate, sodium phosphate). It has a frothy appearance due to the air bubbles mixed into it.
What are the benefits of the salivary glands?
Salivary secretion plays an important role in digestion. It has three primary importances, in addition to its many duties. It serves to soften the mouthfuls of food, which are broken down and pulverized by the teeth (which constitute the majority of the mouth’s surface area). This facilitates digestion in the stomach. Mucin makes the food sticky and slippery, allowing it to be swallowed easily.
Parotid Gland (Sub-ear gland)
It is the largest of the salivary glands in terms of volume. Its base is shaped like a triangular prism facing outward from the cheek, and it is a grayish color. The gland weighs about 20–30 grams on average.
The parotid gland opens into the oral cavity via the **Stensen’s Duct** (Stenon Canal) at the level of the upper second molar tooth. The secretion of the parotid is serous (watery) in nature.
Sublingual Gland
It is a light, almond-shaped gland weighing less than 3 grams on average, composed of countless small vesicles. A long excretory duct passes through its center. This duct opens into the oral cavity next to the muscles that pull the tongue back, underneath the tongue. It also opens into the area under the tongue in the form of smaller ducts. The sublingual gland is situated on the muscles that form the floor of the oral cavity and underneath the tongue. The secretion of this gland is also seromucous but thicker.
Submandibular Gland
The submandibular gland is located on the inner side of the lower jawbone, in the upper section of the hyoid bone in the neck.
The submandibular gland, like the parotid, is a grayish color. Its shape resembles an almond. It weighs about 7–8 grams.
Its excretory duct (**Wharton’s Duct**) terminates with small openings on both sides of the area under the tongue. Its secretion is seromucous, meaning it is a mixed type. Like the parotid and sublingual glands, it produces an enzyme called ptyalin.
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