II. PARTS OF THE DIGESTIVE TRACT A. ORAL CAVITY After ingestion, the physical breakdown of solid foods (mechanical digestion) begins in the oral cavity (mouth). Describe how food is mechanically digested in the oral cavity. Include a discussion of how the teeth, tongue, and saliva work together to convert solid food into a moist, semi-solid mass of food called a bolus. Example: think of how a hard, dry saltine cracker is converted into a moist ball (bolus) in the mouth. B. PHARYNX and ESOPHAGUS 1. After food has been mechanically digested, mixed with saliva, and a bolus has formed, it is swallowed. Swallowing moves the bolus from the mouth into the esophagus. Discuss the events that occur during swallowing. 2. Which portions of the pharynx does food pass through when swallowing

This begins with the gradual breaking down of the food in the mouth, by grinding the food substances with the teeth this is mastication, and the secretion of saliva, which moisten the food, soften it so that the salivary amylase enzyme, carried out the mechanical digestion.

Swallowing is a wavelike muscular contraction which involve the contraction of the longitudinal and circular muscles of the oesophagus, which pushes the bolus down  to the stomach.

The food pass  Oropharynx. While the epiglottis prevents the bolus from entering the trachea.

This is followed by the rolling  up of the tongue, the pushing the broken down food now chyme towards the back of the mouth, pressing it against the soft palate. At this stage a bolus is formed.From here it is pushed into the throat,where it is pushed down the oesophagus by peristalsis.

Explanation:

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