digestion[2]
9:23 PM
the first stage of digestion begins in the mouth, where our teeth grind and chew food, breaking it into small manageable pieces. this chewing process, known as mastication, is dependent upon powerful muscles (masseter and temporalis), as well as smaller muscles that permit fine control. they move the lower jawbone against the upper jaw, enabling the crushing of hard food.
mastication causes exocrine glands under the tongue and in the back of the mouth to secrete a watery liquid called saliva which performs two essential functions:
1. it moistens and compacts the chewed food so the tongue can roll it into a ball (bolus) and push it to the back of your mouth for swallowing and easy passage through the pharynx and
esophagus.
2. saliva contains digestive enzymes which begin the breakdown of carbohydrates.
mastication and saliva secretion work in harmony, as chewing increases the surface area of food which helps to accelerate the breakdown of starch molecules into simple sugars by the digestive enzymes.
more facts about the salivary gland:
Salivary glands:
#1 is Parotid gland,
#2 is Submandibular gland,
#3 is Sublingual gland
the
parotid glands are a pair of glands located in the subcutaneous tissues of the face overlying the mandibular ramus and anterior and inferior to the external ear. the secretion produced by the parotid glands is serous in nature, and enters the oral cavity through the Stensen's duct. despite being the largest pair of glands, only approximately 25% of saliva is produced by the glands.
the
submandibular glands are a pair of glands located beneath the floor of the mouth, superior to the digastric muscles. the secretion produced is a mixture of both serous and mucous and enters the oral cavity via Wharton's ducts. approximately 70% of saliva in the oral cavity is produced by the submandibular glands.
the
sublingual glands are a pair of glands located beneath the floor of the mouth anterior to the submandibular glands. the secretion produced is mainly mucous in nature, however it is categorized as a mixed gland. approximately 5% of saliva entering the oral cavity come from these glands.
information is taken from:
http://en.wikipedia.org/wiki/Salivary_gland
