Science Biojournal- Entry 13

Stage 2 : Oral cavity

Officially this is where digestion in human actually begins, in the oral cavity where food is chewed.

In the mouth, saliva is secreted in large amounts (1-1.5 litre/day) by three pairs of exocrine salivary glands in the oral cavity, which is then mixed with the chewed food by the tongue. There are two types of saliva. One is a thin, watery secretion, and its purpose is to wet the food. The other is a thick, mucous secretion, and it acts as a lubricant and causes food particles to stick together and form a bolus.

The saliva serves to clean the oral cavity and moisten the food, and contains digestive enzymes such as salivary amylase, which aids in the chemical breakdown of polysaccharides such as starch into disaccharides such as maltose. It also contains mucin, a glycoprotein which helps soften the food into a bolus.

The mechanism for swallowing is coordinated by the swallowing center in the medulla oblongata and pons. The reflex is initiated by touch receptors in the pharynx as the bolus of food is pushed to the back of the mouth.Swallowing transports the chewed food into the esophagus, passing through the oropharynx and hypopharynx.

Upon researching on this process, we have hereby learnt about the second process in food digestion