Which layer is primarily involved in nutrient absorption and secretion?

Which layer is primarily involved in nutrient absorption and secretion?

• A. Submucosa
• B. Muscular
• C. Serosa
• D. Mucosa

Answer: (D)

The mucosa is where nutrient absorption and secretion mainly happen. This innermost lining of the GI tract is built for contact with the lumen and contains the epithelial cells that transport nutrients into the body, as well as glands that secrete mucus and digestive enzymes. In the small intestine, enterocytes with microvilli dramatically increase surface area for absorption, and brush-border enzymes finish digestion right at the surface. Goblet cells produce mucus to protect and lubricate the lining, and enteroendocrine cells release hormones that help regulate digestion. The lamina propria beneath the epithelium brings in blood and lymph to carry absorbed nutrients away. The muscularis mucosae helps slightly move the mucosa for better contact with contents. By contrast, the submucosa mainly provides structural support and houses vessels and glands, the muscularis externa drives peristalsis, and the serosa covers the outside. So, the layer responsible for absorption and secretion is the mucosa.

The mucosa is where nutrient absorption and secretion mainly happen. This innermost lining of the GI tract is built for contact with the lumen and contains the epithelial cells that transport nutrients into the body, as well as glands that secrete mucus and digestive enzymes. In the small intestine, enterocytes with microvilli dramatically increase surface area for absorption, and brush-border enzymes finish digestion right at the surface. Goblet cells produce mucus to protect and lubricate the lining, and enteroendocrine cells release hormones that help regulate digestion. The lamina propria beneath the epithelium brings in blood and lymph to carry absorbed nutrients away. The muscularis mucosae helps slightly move the mucosa for better contact with contents. By contrast, the submucosa mainly provides structural support and houses vessels and glands, the muscularis externa drives peristalsis, and the serosa covers the outside. So, the layer responsible for absorption and secretion is the mucosa.