Mouth

The digestive system commences in the mouth. Food is broken up into smaller pieces by the action of the jaws and the teeth and shaped into a ball by the tongue. Mastication renders the food small enough to be swallowed and allows saliva to be thoroughly mixed with it.

The smell and sight of food triggers the reflex action of the secretion of saliva in the mouth. Saliva enters the mouth from three pairs of salivary glands. These are the:

• sublingual glands — located in the lower part of the mouth on either side of the tongue

• submandibular glands — located inside the arch of the mandible

• parotid glands — located superficial to the masseter muscle.

Saliva, containing the enzyme salivary amylase, commences the digestion of starch, or carbohydrates, in the mouth.

KEY FACT

Peristalsis is the coordinated rhythmical contractions of the circular and oblique muscles in the wall of the alimentary tract. These muscles work in opposition to one another to break food down and move it along the alimentary canal. Peristalsis is an automatic action stimulated by the presence of food and occurs in all sections of the alimentary tract.

Saliva o

Mucous secreting cells of salivary glands

Fig 11.2 The salivary glands

How To Reduce Acne Scarring

How To Reduce Acne Scarring

Acne is a name that is famous in its own right, but for all of the wrong reasons. Most teenagers know, and dread, the very word, as it so prevalently wrecks havoc on their faces throughout their adolescent years.

Get My Free Ebook


Post a comment