The walls of the organs of the GI tract are made up of the same four basic layer
ID: 3524028 • Letter: T
Question
The walls of the organs of the GI tract are made up of the same four basic layers. Arrange them in order starting with the one closest to the lumen.
serosa, mucosa, submucosa, and muscularis externa
serosa, muscularis externa, submucosa, and mucosa
mucosa, submucosa, muscularis externa, and serosa
submucosa, serosa, muscularis externa, and mucosa
muscularis externa, serosa, mucosa, and submucosa
a.serosa, mucosa, submucosa, and muscularis externa
b.serosa, muscularis externa, submucosa, and mucosa
c.mucosa, submucosa, muscularis externa, and serosa
d.submucosa, serosa, muscularis externa, and mucosa
e.muscularis externa, serosa, mucosa, and submucosa
Explanation / Answer
Answer is C.
mucosa, submucosa, muscularis externa, and serosa
The GI tract is composed of four layers. Each layer has different tissues and functions. From the inside out they are called: mucosa, submucosa, muscularis, and serosa.
The mucosa is the innermost layer, and functions in absorption and secretion. It is composed of epithelium cells and a thin connective tissue.
The mucosa contains specialized goblet cells that secrete sticky mucus throughout the GI tract. On the mucosa layer, small finger-like projections called villi and microvilli help to increase surface area for nutrient absorption.
The submucosa is a dense, irregular layer of connective tissue with large blood vessels, lymphatics, and nerves that supports the mucosa.
The submucosa is relatively thick, highly vascular, and serves the mucosa. The absorbed elements that pass through the mucosa are picked up from the blood vessels of the submucosa.
The submucosa also has glands and nerve plexuses. The submucosa lies under the mucosa and consists of fibrous connective tissue, separating the mucosa from the next layer, the muscularis externa.
The muscularis in the stomach differs from that of other GI organs in that it has three layers of muscle instead of two. Under these muscle layers is the adventitia—layers of connective tissue that are continuous with the omenta.
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