Question

1. the four layers of the digestive tract, from innermost to outermost, are the:

a. mucosa, submucosa, muscularis, serosa
b. serosa, muscularis, submucosa, mucosa
c. submucosa, mucosa, muscularis, serosa
d. muscularis, submucosa, serosa, mucosa

Explanation:

The digestive tract has four layers. The innermost layer is the mucosa which is in contact with the digestive contents. Next is the submucosa which contains blood vessels, nerves etc. Then comes the muscularis which has smooth muscle for peristalsis. The outermost layer is the serosa (in some parts, adventitia in others like the esophagus). Option a follows this order from innermost (mucosa) to outermost (serosa).

Answer:

A. Mucosa, submucosa, muscularis, serosa