Swallowing

Swallowing, also called deglutition or inglutition in scientific and medical contexts, is a physical process of an animal's digestive tract (e.g. that of a human body) that allows for an ingested substance (typically food) to pass from the mouth to the pharynx and then into the esophagus. In colloquial English, the term "swallowing" is also used to describe the action of gulping, i.e. taking in a large mouthful of food without any biting.

Swallowing is performed by an initial push from back part of the tongue (with the tongue tip contacting the hard palate for mechanical anchorage) and subsequent coordinated contractions of the pharyngeal muscles. The portion of food, drink and/or other material (e.g. mucus, secretions and medications) that moves into the gullet in one swallow is called a bolus, which is then propelled through to the stomach for further digestion by autonomic peristalsis of the esophagus.

Swallowing is an important part of eating and drinking. If the process fails and the bolus to be swallowed mistakenly goes into the trachea, then choking or pulmonary aspiration can occur. In the human body, such incidents are prevented by an automatic trapdoor-like inversion of the epiglottis to temporarily cover the larynx and close off the upper airway, controlled by a complex reflex that facilitates the elevation of the hyoid bone and thyroid cartilage at the same time. The body will also initiate a cough reflex to expel any unwanted material that have accidentally entered the airway. A separate gag reflex, which involves the elevation of the uvula and tightening of the soft palate, prevents food from wrongly entering the nasal cavity above during swallowing.