Salivary Glands: Definition, Function, Diagram, Examples

What Are Salivary Glands?

Salivary glands are vital in the human body, producing and releasing saliva into the oral cavity. It is a clear, slightly watery liquid that contains enzymes such as amylase, initiators of starch digestion. It lubricates food for easy swallowing and has antibacterial properties for the sake of teeth and gum health.

Types of Salivary Glands

The two types of salivary glands are:

Minor Salivary Glands

Major salivary glands are:

Parotid Glands

• Site: Positioned in front of the ears, extending to the cheeks adjacent to the ears.

• Histology: Serous acini-producing watery saliva is found.

• Function: Principally secreting saliva rich in enzymes that initiate digestion.

Submandibular Glands

• Position: Under the lower jawbone.

• Structure: These glands are serous and mucous acini, this gland produces mixed saliva.

• Function: The saliva this gland produces contains enzymes: for lubrication and the initiation of digestion.

Sublingual Glands

• Position: Under the tongue.

• Structure: Principally composed of mucous acini.

• Function: Products are predominantly mucous, allowing lubrication and protection of the oral mucosa.

Minor Salivary Glands

• Location: Widely distributed throughout the cavity of the mouth, in the lips, cheeks, and palate.

• Types: Chiefly mucous glands.

• Functions: Assist in continuous secretion of saliva that moistens the mouth to ease speech and swallowing.

Anatomy of Salivary Glands

The anatomy of salivary glands is discussed below:

Secretory Units (Acini)

• Functional units of salivary glands

• Enveloped by myoepithelium, which contracts to squeeze out the saliva.

Duct System

• Ducts, namely, intercalated, striated, and excretory.

• Carry the saliva from the acini into the oral cavity.

Cell Types

• Serous Cells: Secrete watery saliva rich in enzymes.

• Mucous Cells: Secrete mucus, which contributes to the lubricating action of saliva.

• Myoepithelial Cells: Found surrounding acini and ducts, they squeeze out saliva.

Functions of Salivary Glands

The functions of salivary glands include:

Saliva Production

• Continuously secreted to keep the mouth moist and to help in speech and swallowing.

Enzymatic Digestion

• Starches are broken down into simple sugars in the presence of amylase.

Lubrication and Oral Hygiene

• It moistens food for easy swallowing and prevents drying of the oral tissues.

Antibacterial Action

• The combination of the enzymes and proteins in saliva inhibits bacterial overgrowth in the mouth, ensuring oral health.

Digestive Role

• It initiates the digestion of carbohydrates and lipids and aids digestion.

Composition of Saliva

Saliva is composed of:

• Water: Major part of saliva, providing a clear-fluid medium for various enzymes and other constituents.

• Electrolytes: Electrolytes include the sodium, potassium, chloride, and bicarbonate ions. They maintain a pH balance.

• Mucus: Lubricates the oral mucosa and protects it. Enzymes include amylase, lipase, and lysozyme which participate in digestion and antibacterial activity.

• Antibacterial Compounds: Immunoglobulins and lysozyme play an essential role in preventing various infections of the oral cavity.

Salivary Glands NEET MCQs (With Answers & Explanations)

Important questions asked in NEET from this topic are:

• Types of salivary glands

• Role of salivary glands

Practice Questions for NEET

Q1. Which of the following is a digestive gland associated with the alimentary canal?

1. Liver

2. Pancreas

3. Salivary Gland

4. All of the above

Correct answer: 4) All of the above

Explanation:

The digestive system comprises salivary glands, the liver, and the pancreas, which all secrete essential substances for digestion. The salivary glands will secrete saliva containing salivary amylase that breaks starch into sugar. The liver secretes bile juice, which is used in the emulsification of fats. The gland from the pancreas will release pancreatic juice, which will contain trypsinogen and amylase that will digest proteins and carbohydrates. All these glands, along with their enzymes, are essential in the digestive process.

Hence, the correct answer is option 4)All of the above.

Q2. The pH of saliva is maintained at

1. 6.85 - 7.4

2. 5.0 - 6.0

3. 3.0 - 4.5

4. 4.0 - 6.1

Correct answer: 1) 6.85 - 7.4

Explanation:

Bicarbonate and phosphate ions are present in the saliva and function as chemical buffers, maintaining saliva at a pH between 6.85 and 7.4.

Hence, the correct answer is option 1) 6.85 - 7.4.

Q3. The parotid glands bear a duct called

1. Wharton’s duct

2. Rivinus duct

3. Stenson’s duct

4. Salivary duct

Correct answer: 3) Stenson’s duct

Explanation:

The parotid gland secretes saliva into the mouth through the parotid duct or Stenson’s duct, which is located near the second upper molar tooth. The parotid gland, the largest of the salivary glands, secretes serous saliva rich in enzymes, aiding in the initial digestion of starches and lubricating food for swallowing. Saliva is delivered into the mouth through the parotid duct, also known as Stenson’s duct, which opens near the second upper molar tooth on the buccal mucosa. The gland is located anterior to the ear and extends inferiorly to the mandibular angle. It is innervated by the glossopharyngeal nerve (cranial nerve IX) and plays a role in maintaining oral health by producing antibacterial enzymes.

Hence, the correct answer is option 3) Stenson’s duct.

Also Read:

• MCQs on Salivary Glands

• Pancreas Function in Human Body

• Digestion in Ruminants

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