Final answer:
The internal folds of the stomach are known as rugae, which enhance its ability to expand and increases the surface area for digestion and absorption.
Step-by-step explanation:
The internal folds of the stomach are known as rugae.
In biology, the term rugae refers to the large folds within the stomach lining. Contrary to the term 'convolutions', these characteristic folds are specific to the gastric mucosa, allowing the stomach to expand substantially when needed. The muscularis layer of the stomach, which includes an inner oblique smooth muscle layer in addition to circular and longitudinal layers, facilitates the vigorous churning and mixing of food.
This churning helps to mechanically break down food into smaller particles. The rugae, working in tandem with the muscularis, increase the stomach's surface area and flexibility, accommodating for varying volumes of ingested food.