The swallowing is the passage of the bolus from the mouth to the pharynx and then the esophagus. It is started by pushing the food bolus into the pharynx with the tongue.
The pharynx is a common passageway in the respiratory and digestive tracts, through which both air and the food bolus pass. To prevent the food bolus from going through the airways , we have a cartilage called the epiglottis that blocks the passage of the bolus towards the larynx, preventing us from choking.
After the pharynx, the digestive tube continues with the esophagus, a tube about 25 cm in length that is connected to the stomach through the cardia, a sphincter that controls the entry of the food bolus into the stomach and prevents its backward movement.
The food bolus travels through the esophagus through peristaltic movements, contractions and dilations of the muscles in the wall of the esophagus that knead, mix and advance the food bolus into the stomach.
Activity: Digestion
3.3.- What is the function of the epiglottis?
3.4.- What does it mean that "the food has gone the other way"?
3.5.- What are peristaltic movements? Draw a sequence showing the progress of the peristaltic movement in the esophagus. How can the bolus move when astronauts eat without being subjected to the action of gravity?
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