Describe the process of swallowing as food moves from the oral cavity to the stomach; include the processes of the four phases of swallowing

Answer 1

The first phase is the oral preparatory phase where food is chewed and mixed with saliva. The second phase, the oral transit phase, consists of voluntary movement of the bolus of food from the front of the oral cavity to the back. The third phase of swallowing is known as the pharyngeal phase. The most important part of this phase is to ensure the bolus is directed into the esophagus and is prevented from entering the trachea. This is initially accomplished when the uvula seals off the nasal passage so food does not leak into the nose. Next, laryngeal muscles contract and seal off the glottis. The epiglottis also tilts upward to assist in preventing food from entering the larynx. The final phase of swallowing is the esophageal phase. The upper esophageal sphincter (UES), when open, allows the bolus to enter the esophagus. When the sphincter is closed, it prevents air from entering the GI tract during breathing. After the bolus of food moves through the UES into the esophagus, the sphincter closes and normal breathing will resume.