Which salivary gland produces the most saliva

Salivary glands and saliva

The salivary glands


The large salivary glands are responsible for the production of saliva: the parotid gland, the mandibular salivary gland and the sublingual salivary gland. In addition, humans have between 600 and 1000 small salivary glands, which are distributed over the mucous membrane of the mouth and throat and secrete saliva there. The salivary glands produce up to one liter of saliva every day.

Anatomy and function of the salivary glands

 
The large salivary glands can be anatomically divided into 3 paired salivary glands because of their location. On the one hand, there are the two parotid glands (glandula parotis), the two mandibular salivary glands (glandula submandibularis) and the two sublingual glands (glandula sublingualis). All three salivary glands can be found in both the left and right halves of the face and are therefore referred to as pairs.
 

The parotid gland


The parotid gland, Latin parotid gland, is not only the largest salivary gland, but also the most important. It is a serous gland, which means it produces a liquid, ferment-rich secretion. The parotid gland can be found, as its name suggests, near the ear. It rests firmly on the masseter muscle, one of the four masticatory muscles, and extends from here to the side of the ear. At the top, it extends from the zygomatic arch down to the angle of the jaw. In its shape, it resembles a triangle and weighs up to 30 grams.
 
The parotid gland is surrounded by a connective tissue capsule (also called fascia parotidea or parotid gland), which is a pure pseudocapsule, as it does not actually form a separating layer around the salivary gland. Instead, the connective tissue pulls itself into the interior of the parotid gland and divides it into small lobules. The gland cells that produce primary saliva are located in these lobules. This primary saliva still changes in one composition until it is actually released into the oral and pharynx cavity.
 
The excretory duct (also called the parotid duct or Stenon's duct) can be found in the upper third of the parotid gland. It runs along the masseter muscle of the masticatory muscles and penetrates both the cheek muscle (musculus buccinator) and the cheek mucous membrane. The Stenon's duct is 6 centimeters long and can be seen in the oral cavity on the outer inner wall of the cheek at the level of the first and second upper molars as a small, dark point.
 

The mandibular salivary gland


The submandibular gland, Latin for the submandibular gland, is a mixed, seromucous gland that supplies the majority of a person's total saliva. It can be found in the lower jaw angle, the so-called submandibular trigonum, between the lower jaw bone and the digastric muscle belonging to the masticatory muscles.
 
The duct of the mandibular salivary gland (also known as the submandibular duct or Wharton's duct) is about two inches long. It connects with the duct of the sublingual salivary gland and ends on the starvation wart (Latin: Caruncula sublingualis), a small papilla that can be seen on both sides of the frenulum under the tongue.
 

The sublingual salivary gland


The sublingual salivary gland, Latin glandula sublingualis, is a purely mucosal gland, so it only produces a thick secretion. As its name suggests, it is located under the tongue. The sublingual salivary gland can be divided into two parts: the major sublingual gland and the minor sublingual gland. The anterior part (glandula sublingualis major) is a compact set of glands with a single, common duct (ductus sublingualis major), which ends together with the duct of the mandibular salivary gland on the starvation wart. The posterior part (glandula sublingualis minores) consists of about 150 individual glands. They have numerous ducts that end along the side of the tongue in the floor of the oral cavity.

The spit


The salivary glands produce up to one liter of saliva (saliva) per day. However, the actual volume of saliva produced depends on various factors such as climate, fluid intake, diet, age and gender.

Saliva secretion is mainly triggered by the active chewing process, but can also be triggered by taste, visual or physical stimuli. A certain amount of saliva is produced continuously without external influences. This process is called resting secretion. The external influences already mentioned lead to a so-called irritant secretion, i.e. the production of saliva is stimulated and the rate of secretion of the saliva increases significantly.


 
Resting secretStimulating secretions
origin
mainly from the lower jaw salivary gland, the sublingual salivary gland and the small salivary glands
predominantly from the parotid gland
consistency
relatively thick
thin
content
Mucins (structural components of mucus), few enzymes
Enzymes, less mucins
PH value
5,5 - 6
7,6 - 7,8

Listed according to Probst, Grevers and Iro



Composition of saliva

 
The saliva consists of 99.5% water, the remaining 0.5% are organic and cellular components. In addition to water, the secretion of the parotid gland mainly contains electrolytes and trace elements such as chloride, phosphate, bicarbonate, magnesium, iron, copper, zinc, selenium, lead, fluoride, bromide, iodine, rhodanite and nitrate.

Immunoglobulins can also be found in saliva, which increase in inflammatory processes, as well as proteins that contribute to the defense, amylase, albumin, lysozyme, kallikrein and protease inhibitors. The most important substance found in saliva, however, is α-amylase, an enzyme that breaks down food and is the most important digestive enzyme that can be found in saliva.

List of the most important saliva constituents (according to Hochstrasser and Eigner):

description
function
α-1,4-glycanohydrolase (amylase)
Depletion of starch
Macroamylase
unknown
Kininogenase (kallikrein)
Release of vasoactive kallidin from kininogen
β-N-acetyl-D-glucosaminidase (lysozyme)
Breakdown of bacterial cell walls
Proteins rich in proline
antibacterial, approx2+-stabilizing
Statherin (tyrosine-rich protein)
antibacterial
α2-Microglobulin
streptococcal agglutinating
Fibronectin
streptococcal agglutinating
 

Function of saliva


The functions of saliva are quite diverse. On the one hand, saliva has a protective function, i.e. it has a protective effect on the oral mucosa and the mucous membrane of the upper respiratory tract against mechanical friction from food and promotes the immune defense through immunoglobulins. To a certain extent, the saliva also has a bactericidal effect. Furthermore, the saliva naturally also has a function in digestion. It gums up food (makes it viscous for the act of swallowing) and already initiates the breakdown of starch by amylase.

In addition, the saliva also plays a role in the excretion of endogenous and exogenous substances. They can be eliminated from the circulation through it. These include good ions such as iodine and fluorine, but also harmful viruses that can trigger diseases such as Epstein-Barr, polio, hepatitis B and cytomegaly.

Also, don't forget the important role saliva plays in protecting your teeth. Tooth enamel is attacked and demineralized by acidic foods and liquids. Since the saliva has a slightly alkaline pH value, the acid can be balanced. In addition, the substances calcium phosphate and fluoride present in saliva help reminalize teeth that have already been attacked by settling in the tooth enamel.


Sources used:
Berghaus, Alexander, Gerhard Böhme and Gerhard Rettinger. Ear, nose and throat medicine. Stuttgart: George Thieme Verlag KG, 1996.

Grevers, Gerhard, Heinrich Ito and Rudolf Probst. Ear, nose and throat medicine. Stuttgart: Georg Thieme Verlag KG, 2008 [3].


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