The structure and functions of salivary glands in human beings
There are three pairs of salivary glands – the parotid, submandibular and sublingual. These secret saliva which begins the process of digestion in the mouth. The parotid glands lie below and slightly in front of each ear. They are the largest of the salivary glands. The submandibular glands are situated just under the cover of the angle of the mandible.
The sublingual glands lie in the anterior part of the floor of the mouth between the tongue and mandible. They pour their secretions directly into the mouth. The digestive juices secreted by these glands are commonly called saliva.
This is a fluid consisting of 90% water and a digestive enzyme ptyalin (salivary amylase). The carbohydrate gets partly digested due to the action of saliva. The saliva also contains mucin and a small quantity of calcium salts. The main functions of saliva are
1. It moistens the mouth and tongue.
2. It lubricates food so that it can be rolled into a soft mass or bolus which can be easily swallowed.
3. Ptyalin acts on the starch and breaks them up into dextrins and maltose.
4. Saliva also dissolves the part of the food which stimulates taste buds.
5. It has a cleansing action in the mouth.