CalRegional Medical Assistant Practice Exam

Which term matches the definition: Has two layers of involuntary muscles; the inner layer forms circles around it, whereas the outer layer runs longitudinally along its approximately 10-inch length?

Bolus

Colitis

Esophagus

Two layers of smooth muscle arranged as an inner circular layer and an outer longitudinal layer form a muscular tube that moves contents along by peristaltic contractions. The circular layer squeezes around the lumen, while the longitudinal layer shortens and lengthens the tube as it contracts, enabling the contents to be pushed forward. This setup is characteristic of the esophagus, a roughly ten-inch-long passage that transports swallowed food from the pharynx to the stomach. The other options don’t describe a two-layer muscle tube: a bolus is simply a chewed mass of food, colitis is inflammation of the colon, and the alimentary canal refers to the entire digestive tract rather than a specific segment with two muscle layers.

Alimentary canal