The salivary glands and their functions
All oral cancer in my position are divided into two groups:
- 1) the small salivary glands mucosa or submucosal layer – labial, palatine, buccal, dental, lingual, 2) major salivary glands – the parotid, submandibular and sublingual.
The salivary gland is not only involved in digestion, but at a distance from the body of the residual products of metabolism (excretory function) and release the hormone that acts on carbohydrate metabolism, like pancreatic hormones (endocrine function). In some animals, such as dogs, salivary glands are also involved in thermoregulation. The activity of the salivary glands is different in animals and humans.
There is a natural secretion of salivary glands in different nutrients. Horses saliva during feeding hay or straw in the 4-5 times the weight of the food eaten but, when feeding oats or corn – 2 times, and feeding fresh grass saliva equal weight eaten grass or even half.
When the conditioned stimulus, when poling hay is also separated by 2 times more saliva than the poling oats. The main role of saliva in horses is wetted roughage. Saliva is separated only when feeding and preferably on the side of chewing. The daily amount of saliva – about 40 dm3.
In ruminants, such as cows, on bran, bagasse and beet parotid separate 2 times more saliva than submandibular and hay – 5 times more.
Saliva ruminants has a very high alkalinity. Its role consists in macerating food, and most importantly – to neutralize acids produced in the rumen by fermentation using microorganisms of feed. The roughage, the more alkaline saliva. Parotid saliva of ruminants continuously separated irrespective of feeding, which enhances salivation. Submandibular and sublingual glands are separated only saliva during feeding. The daily amount of saliva in cows about 60 dm3.
Pigs salivating at the rough and dry food and more than succulent. The daily amount of saliva about 15 dm3.
It is assumed that people parotid, submandibular and sublingual glands are functioning continuously, alone separated 0.25 cm3 / min. This separation is a reflex, as it is called attachment funnel Lashley – Krasnogorsk (T. Hayashi et al., 1963). The amount of saliva secreted from the glands of the same name, about the same. Different people and have the same face value of this basic secretion fluctuates throughout the day. Salivation increases during speaking and writing.
Happy separates the greatest amount of saliva. At night, the main value of secretion varies strongly. Food intake increases the basic secretion and fasting reduces it.
In humans, dry food is not so important for saliva as in animals. The difference in the amount of saliva to food products containing water, and dry – negligible.
There is also natural adaptations and mixed parotid gland in food and non-food substances both in quantity of saliva or content therein organic solid substances. It probably depends on the person cooking the food.
The secretion of saliva in humans strongly excite only acid. Milk weaker ons salivation in humans than in dogs. For infants admixture of saliva to milk may be more important than for adults, a hook as saliva promotes the formation of a loose bunch when curdling milk in the stomach and so makes it easier to digest.
The secretion of saliva in humans very exciting water. Drinking water not only increases the secretion of saliva, but also dramatically increases the viscosity of the submandibular and the sublingual salivary glands.
Reflex salivation decreases with deprivation of water. Heating and cooling water is increased salivation. Cold water and ice enhance secretion compared with warm water.
Increased salivation when chewed. The more food is crushed, the more vigorously salivation.
On the side where the chewing separated more saliva. When muscular work continuous secretion of saliva decreases and increases the viscosity of saliva.
Salivation is also inhibited during intense mental work, when emotions.
Vibrations caused salivation reflex weak mechanical and chemical stimulation of the receptors of the stomach and duodenum to enroll in them water and liquid food (SI Halperin, 1934).
The daily amount of saliva in humans of about 1.5 dm3. Almost all the saliva is swallowed, only some of it is lost when spitting and partly evaporation from the surface of the oral cavity.
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