Salivary Glands – Definition, Types, Location, Size, Ducts, Diagram, Characteristics, Secretion, Structure and Function

Salivary Glands - Definition, Types, Location, Size, Ducts, Diagram, Characteristics, Secretion, Structure and Function

Definition of Salivary Glands

The Salivary Glands are a group of exocrine glands responsible for the production and secretion of Saliva. Saliva is a watery fluid that is important for various functions in the oral cavity, including lubrication, digestion, protection against bacteria and taste perception. The Salivary Glands are an essential part of the human body’s digestive system and play a crucial role in maintaining oral health

Types of Salivary Glands – Location ,Size and Salivary Glands Ducts

The Salivary Glands can be divided into two groups

  • Major Salivary Glands 
  • Salivary Glands Minor

Major Salivary Glands 

The major Salivary Glands are three pairs of large glands that produce the majority of Saliva. These include the 

  • Parotid Glands
  • The Submandibular Glands 
  • The Sublingual Glands.
Salivary Glands - Definition, Types, Location, Size, Ducts, Diagram, Characteristics, Secretion, Structure and Function
Major glands – Parotid Glands The Submandibular Glands  The Sublingual Glands.

Parotid Glands

Location

Located on both sides between the ramus of the mandible and the sternocleidomastoid muscle.

Size

The Parotid Glands are the largest of the major Salivary Glands.

Salivary Glands Duct

The excretory ducts of the Parotid Glands are known as Stensen’s ducts. They open on the buccal wall at the level of the maxillary second molar of the upper jaw.

Characteristics

The Parotid Glands consist mainly of serous acinar cells. They produce a watery Saliva containing enzymes such as amylase and lysozyme.

Submandibular Glands

Location

Located below the tongue, in the floor of the mouth.

Size

The Submandibular Glands are smaller in size compared to the Parotid Glands, but larger than the Sublingual Glands.

Salivary Glands Duct

The excretory ducts of the Submandibular Glands are called Wharton’s ducts. They open into the sublingual papilla under the tongue.

Characteristics

The Submandibular Glands consist of both serous and mucous acinar cells. They produce a mixed Saliva containing both mucous and serous components.

Also Check – What is the Function of the Digestive Enzymes ?

Sublingual Glands

Location

Found beneath the sublingual fold, at the base of the mouth.

Size

The Sublingual Glands are the smallest of the major Salivary Glands.

Salivary Glands Duct

The Sublingual Glands have several excretory ducts that open along the sublingual folds.

Characteristics

The Sublingual Glands consist mainly of mucous acinar cells. They secrete a mucilaginous Saliva containing mucins and glycoproteins.

Also Check – Digestive Glands – Definition , Types and Functions

Minor Salivary Glands

Salivary Glands - Definition, Types, Location, Size, Ducts, Diagram, Characteristics, Secretion, Structure and Function
Minor Salivary Glands

Minor Salivary Glands are small Salivary Glands distributed throughout the mouth. There are hundreds of these glands that play an important role in maintaining oral health and the digestive process.

Location

Scattered throughout the oral mucosa, including the lips, cheeks, tongue, palate, floor of the mouth, pharynx and larynx.

Size

The minor Salivary Glands are small in size and vary in number throughout the oral cavity.

Salivary Glands Duct

Each minor Salivary gland has its own excretory duct or opening.

Characteristics

The minor Salivary Glands consist of both serous and mucous acini. They produce a thin, watery Saliva that helps to moisten and cleanse the mouth.

The minor Salivary Glands are classified based on their location – 

Labial glands- they are located in the lips.

Buccal glands- They are located in the cheeks.

Palatine glands- They are located in the hard and soft palate.

Lingual glands- Located on the tongue.

Salivary Glands can also be classified according to the type of secretion they produce-

Serous glands- Produce a thin, watery Saliva that contains enzymes and electrolytes.

Mucous glands- Produce a thick, viscous Saliva that contains mucins and glycoproteins.

Seromucous (mixed) glands- Produce a combination of both types of Saliva.

Also Check – Explain the Role of Mouth in Digestion of Food

Salivary Glands Structure

Salivary Glands - Definition, Types, Location, Size, Ducts, Diagram, Characteristics, Secretion, Structure and Function
Salivary Glands Structure

The Salivary Glands are complex structures composed of different cell types and supported by a network of blood vessels and nerves. Understanding their structure provides information about their functions and how Saliva is produced and delivered.

Acinar Cells

Acinar cells are the primary cells in the Salivary Glands. They are responsible for the production of Saliva. These cells are arranged in clusters known as acini. Acinar cells synthesise and secrete the components of Saliva, including water, electrolytes, enzymes and mucins.

Ductal Cells

Ductal cells line the ducts within the Salivary Glands. Their main function is to transport Saliva from the acinar cells into the oral cavity. Ductal cells modify the composition of Saliva by reabsorbing certain electrolytes and water, resulting in the final composition of the secreted Saliva.

Myoepithelial Cells

Myoepithelial cells are located around the acinar cells. They have contractile properties and play a crucial role in facilitating the movement of Saliva. When stimulated, the myoepithelial cells contract, causing a squeezing action that helps move Saliva out of the acinar cells and into the ducts.

Blood Supply and Innervation

The Salivary Glands receive a rich blood supply to support their metabolic needs. The arteries supply the glandular tissue with oxygen and nutrients, while the veins remove waste products. In addition, the Salivary Glands are innervated by the autonomic nervous system, which controls involuntary body functions. The parasympathetic nervous system stimulates the Salivary Glands to produce Saliva, while the sympathetic nervous system inhibits Saliva production.

Functions of Salivary Glands

  1. Lubrication- Saliva from the Salivary Glands helps moisten the mouth and throat, making swallowing and speaking comfortable.
  2. Digestion- Salivary Glands produce enzymes such as amylase and lysozyme that initiate the breakdown of starch and fats in food, aiding the digestive process.
  3. Antimicrobial effect- Saliva contains antibacterial substances such as immunoglobulin A, lactoferrin and lysozyme, which kill or inhibit the growth of harmful microorganisms in the mouth and thus contribute to oral health.
  4. Buffering- Saliva contains bicarbonate and phosphate ions that act as buffers, neutralising the acids produced by bacteria and food in the mouth. This buffering action helps prevent tooth decay and erosion.
  5. Hormone Regulation- Saliva contains various hormones, such as cortisol, melatonin and leptin. These hormones regulate important physiological processes such as the stress response, sleep-wake cycle and appetite control.
  6. Taste Sensation- Saliva plays a role in taste perception. It dissolves molecules in the food so that they can interact with the taste receptors on the tongue and enhance the sense of taste.

Also Check – Nutrition in Human Beings

Frequently asked Important question on Salivary Glands 

What are minor Salivary Glands?

Answer – Minor Salivary Glands are small Salivary Glands dispersed throughout the mouth that play a role in maintaining oral health and the digestive process.

Where are minor Salivary Glands located?

Answer – Minor Salivary Glands are scattered throughout the oral mucosa, including the lips, cheeks, tongue, palate, floor of the mouth, pharynx, and larynx.

What is the size of minor Salivary Glands?

Answer – Minor Salivary Glands are small in size and vary in number throughout the oral cavity.

Do minor Salivary Glands have their own excretory ducts or openings?

Answer – Yes, each minor Salivary gland has its own excretory duct or opening.

What are the characteristics of minor Salivary Glands?

Answer – Minor Salivary Glands comprise both serous and mucous acini. They produce a thin, watery Saliva that helps moisten and cleanse the mouth.

What are the classifications of minor Salivary Glands based on their location?

Answer – The classifications of minor Salivary Glands based on their location include labial glands (in the lips), buccal glands (in the cheeks), palatine glands (in the hard and soft palate), and lingual glands (in the tongue).

How can Salivary Glands be classified based on the nature of their secretion?

Answer – Salivary Glands can be classified into serous glands (producing thin, watery Saliva containing enzymes and electrolytes), mucous glands (producing thick, viscous Saliva containing mucins and glycoproteins), and seromucous (mixed) glands (producing a combination of both types of Saliva).

What are the functions of Salivary Glands?

Answer – The functions of Salivary Glands include lubrication, digestion, antimicrobial action, buffering, hormone regulation, and taste sensation.

How does Saliva contribute to lubrication?

Answer – Saliva moistens the mouth and throat, providing lubrication for comfortable swallowing and speaking.

What is the role of Salivary Glands in digestion?

Answer – Salivary Glands produce enzymes like amylase and lysozyme that initiate the breakdown of starches and fats in food, aiding in the digestion process.

How do Salivary Glands contribute to antimicrobial action?

Answer – Saliva contains antibacterial substances, such as immunoglobulin A, lactoferrin, and lysozyme, which help kill or inhibit the growth of harmful microorganisms in the mouth, contributing to oral health.

How do Salivary Glands help in buffering?

Answer – Saliva contains bicarbonate and phosphate ions that act as buffers, neutralizing the acids produced by bacteria and food in the mouth. This buffering action helps prevent tooth decay and erosion.

What is the role of Salivary Glands in hormone regulation?

Answer – Saliva carries various hormones, such as cortisol, melatonin, and leptin, which regulate important physiological processes like stress response, sleep-wake cycles, and appetite control.

How does Saliva contribute to taste sensation?

Answer – Saliva dissolves molecules in food, allowing them to interact with taste receptors on the tongue and enhancing the sense of taste.

What is the function of Salivary Glands?

Answer – Salivary Glands are responsible for producing and secreting Saliva, which has various functions within the oral cavity, including lubrication, digestion, protection against bacteria, and taste perception.

What are the main types of cells found in the Salivary Glands?

Answer – The main types of cells found in the Salivary Glands are acinar cells, ductal cells, and myoepithelial cells.

What is the function of acinar cells?

Answer – Acinar cells are responsible for producing Saliva. They synthesize and secrete the components of Saliva, including water, electrolytes, enzymes, and mucins.

What is the function of ductal cells?

Answer – Ductal cells line the ducts within the Salivary Glands and their main function is to transport Saliva from the acinar cells to the oral cavity. They modify the composition of Saliva by reabsorbing certain electrolytes and water.

What is the function of myoepithelial cells?

Answer – Myoepithelial cells are located around the acinar cells and have contractile properties. They play a crucial role in facilitating the movement of Saliva by contracting and squeezing Saliva from the acinar cells into the ducts.

How are the Salivary Glands supplied with blood and innervated?

Answer – The Salivary Glands receive a rich blood supply through arteries that deliver oxygen and nutrients, while veins carry away waste products. The Salivary Glands are also innervated by the autonomic nervous system, with the parasympathetic nervous system stimulating Saliva production and the sympathetic nervous system inhibiting it.

How are Salivary Glands classified based on their size and location?

Answer – Salivary Glands can be classified into major and minor glands. The major Salivary Glands include the Parotid Glands, Submandibular Glands, and Sublingual Glands.

Where are the Parotid Glands located?

Answer – The Parotid Glands are situated bilaterally between the ramus of the mandible and the sternocleidomastoid muscle.

What is the size of the Parotid Glands?

Answer – The Parotid Glands are the largest among the major Salivary Glands.

What are the excretory ducts of the Parotid Glands called, and where do they open?

Answer – The excretory ducts of the Parotid Glands are known as Stensen’s ducts, and they open on the buccal wall at the level of the maxillary second molar.

What are the characteristics of the Parotid Glands?

Answer – The Parotid Glands predominantly consist of serous acinar cells. They produce a watery Saliva that contains enzymes like amylase and lysozyme.

Where are the Submandibular Glands located?

Answer – The Submandibular Glands are located beneath the tongue, in the floor of the mouth.

What is the size of the Submandibular Glands?

Answer – The Submandibular Glands are smaller in size compared to the Parotid Glands but larger than the Sublingual Glands.

What are the excretory ducts of the Submandibular Glands called, and where do they open?

Answer – The excretory ducts of the Submandibular Glands are called Wharton’s ducts, and they open at the sublingual papilla under the tongue.

What are the characteristics of the Submandibular Glands?

Answer – The Submandibular Glands consist of both serous and mucous acinar cells. They produce a mixed Saliva that contains both mucous and serous components.

Where are the Sublingual Glands located?

Answer – The Sublingual Glands are found beneath the sublingual fold, on the floor of the mouth.

What is the size of the Sublingual Glands?

Answer – The Sublingual Glands are the smallest among the major Salivary Glands.

How do the excretory ducts of the Sublingual Glands open?

Answer – The Sublingual Glands have multiple excretory ducts that open along the sublingual folds.

What are the characteristics of the Sublingual Glands?

Answer – The Sublingual Glands primarily consist of mucous acinar cells. They secrete a mucous Saliva that contains mucins and glycoproteins.

What are the functions of Saliva?

Answer – Saliva has various functions, including lubricating the oral cavity, aiding in digestion, protecting against bacteria, and facilitating taste perception.

How do the ductal cells modify the composition of Saliva?

Answer – Ductal cells reabsorb certain electrolytes and water from the Saliva, leading to the final composition of the secreted Saliva.

What is the role of myoepithelial cells in Saliva movement?

Answer – Myoepithelial cells contract when stimulated, causing a squeezing action that helps propel Saliva from the acinar cells into the ducts.

How are the Parotid Glands different from the submandibular and Sublingual Glands in terms of their cellular composition?

Answer – The Parotid Glands consist predominantly of serous acinar cells, while the Submandibular Glands have both serous and mucous acinar cells, and the Sublingual Glands primarily consist of mucous acinar cells.

What is the role of the autonomic nervous system in Salivary gland function?

Answer – The autonomic nervous system controls the involuntary functions of the Salivary Glands. The parasympathetic nervous system stimulates Saliva production, while the sympathetic nervous system inhibits it.

How do the major and minor Salivary Glands differ?

Answer – The major Salivary Glands (parotid, submandibular, and Sublingual Glands) produce the majority of Saliva, while the minor Salivary Glands are smaller in size and are located throughout the oral cavity.

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