What does the submucosa layer do?

What does the submucosa layer do?

• A. Blood vessels in this layer carry absorbed nutrients throughout the body.
• B. Secretes serous fluid to lubricate the outer surface.
• C. Contracts to move materials through the canal.
• D. Absorbs water in the colon.

Answer: (A)

The submucosa’s job is to provide vascular and neural support for the mucosa, including blood vessels that carry absorbed nutrients away from the intestinal lining. After nutrients are absorbed by the mucosal epithelium, they enter these vessels and are transported via the bloodstream to the liver and then onward to the rest of the body. This layer also houses nerves (the submucosal plexus) that regulate blood flow and secretion to the mucosa. The other options point to functions of other layers: lubricating secretions come from serous/secretory tissues beyond the submucosa, muscle contractions that move contents are from the muscularis externa, and water absorption occurs mainly in the mucosa of the colon.

The submucosa’s job is to provide vascular and neural support for the mucosa, including blood vessels that carry absorbed nutrients away from the intestinal lining. After nutrients are absorbed by the mucosal epithelium, they enter these vessels and are transported via the bloodstream to the liver and then onward to the rest of the body. This layer also houses nerves (the submucosal plexus) that regulate blood flow and secretion to the mucosa.

The other options point to functions of other layers: lubricating secretions come from serous/secretory tissues beyond the submucosa, muscle contractions that move contents are from the muscularis externa, and water absorption occurs mainly in the mucosa of the colon.