Final answer:
The backward flow of food from the stomach after a meal is called acid reflux, or heartburn, and is related to the malfunctioning gastro-esophageal sphincter. A severe form of backward flow is emesis or vomiting. These conditions can arise from various causes, including increased abdominal pressure and digestive tract irritants.
Step-by-step explanation:
Backward Flow of Food After a Meal
The term for the backward flow of food from the stomach after a meal is acid reflux or heartburn. This occurs when the contents of the stomach, including acidic digestive juices, escape into the esophagus. The condition is related to the gastro-esophageal sphincter, which is meant to prevent this backward flow when no swallowing action takes place. However, in humans, this is not a true sphincter and may sometimes fail to keep the stomach contents from rising up, especially when the individual experiences increased abdominal pressure or changes in body position.
Another more severe form of this backward flow is known as emesis, or vomiting, which is the forceful expulsion of stomach contents through the mouth and is often caused by irritants affecting the digestive tract.
The process of digestion includes various stages like propulsion, where food is moved through the digestive tract via the voluntary action of swallowing and the involuntary action of peristalsis. Peristalsis is characterized by alternating waves of contraction and relaxation of alimentary wall smooth muscles helping in propelling the bolus toward the stomach.