Different Phases of Swallowing or Deglutition

Swallowing, or deglutition, is a complex process that involves several stages to move food or liquid from the mouth to the stomach. There are four stages of deglutition: the preparatory phase, the oral phase, the pharyngeal phase, and the esophageal phase.

The first stage of deglutition is the preparatory phase. This phase occurs before the food or liquid enters the mouth and involves a sensory assessment of the food or beverage. We use our senses of taste, smell, and touch to determine the texture, temperature, and consistency of the food or liquid. The muscles of the lips, cheeks, and tongue work together to position the food or liquid in the mouth for the oral phase. The tongue forms a bolus, or a compact ball of food, by pressing the food or beverage against the hard palate, making it easier to swallow.

The second stage of deglutition is the oral phase. This phase begins when the food or liquid enters the mouth. The tongue and cheek muscles work together to move the bolus toward the back of the mouth. During this stage, the food or liquid is mixed with saliva, which helps to moisten and lubricate the food, making it easier to swallow. The soft palate also rises to close off the nasal passage, preventing food or liquid from entering the nasal cavity.

The third stage of deglutition is the pharyngeal phase. This stage begins when the bolus reaches the back of the mouth and triggers a reflexive swallowing response. The epiglottis, a flap of tissue at the base of the tongue, closes off the entrance to the trachea, or windpipe, to prevent food or liquid from entering the lungs. The pharyngeal muscles then contract, pushing the bolus down the pharynx and into the esophagus.

The final stage of deglutition is the esophageal phase. This stage begins when the bolus enters the esophagus, a muscular tube that connects the pharynx to the stomach. The muscles in the esophagus contract in a coordinated wave-like motion, called peristalsis, to move the bolus down the esophagus and into the stomach. The lower esophageal sphincter, a muscular ring at the bottom of the esophagus, then relaxes to allow the bolus to enter the stomach.

In conclusion, deglutition is a complex and coordinated effort involving four stages to move food or liquid from the mouth to the stomach. The preparatory, oral, pharyngeal, and esophageal phases all play a crucial role in ensuring that we can take in nutrients and maintain our bodily functions. Any disruption in the swallowing process can lead to dysphagia, or difficulty swallowing, which can have serious consequences for our health. Understanding the steps of deglutition can help us appreciate the importance of this essential process and the role it plays in our daily lives.