The Structure of the Mucosa and Muscularies Externa - Essay Example

The epithelium lining of the stomach has mucus-producing cells that form the secretory sheath (glandular epithelium). The mucus is important for protecting the mucosa from the acidic contents of the stomach. The epithelium is also lined with endocrine cells that stimulate the production of acid and digestive enzymes (Johnson, 2005, 23). The lamina propria lining the stomach is composed of loose connective tissue. Lymph vessels, nerves and large blood vessels are located in the mucosa that is composed of loose connective tissues. In the stomach, the muscularity externa is composed of three layers of muscles that are the oblique inner, circular middle and longitudinal outer layers that run in opposite directions to allow great motility in the stomach for mixing and churning ingested food.

The small intestines

The small intestine mucosa has various structural features that are essential for increasing the luminal surface area supporting the main function of the small intestine of absorption of the degraded food components. Along the mucosa and submucosa are plicae circulares that are crescent-shaped folds that extend on around 1/3 of the small intestine lumen The lumen is lined with simple columnar epithelium. The ileum and jejunum are covered with serosa while the duodenum has serosa on the anterior surface (Feneis & Dauber, 2000, 42).

The entire mucosa of the intestinal lining forms villi that are important for increasing the surface area that food absorption takes place. The surface of the villi is composed of simple epithelium for easy absorption. The lamina propria is similar to that of the stomach usually cell-rich. The submucosa layer contains glands on the duodenum “Brunner’s glands” that produce mucus protecting the duodenal mucosa from the acidic content from the stomach (Di Mauro et al. 2013, 15). The muscular externa has two layers the inner thicker circular layer for mixing and the outer thinner longitudinal layer for the continuous peristalsis activity of the small intestines.

Large intestines

It is the terminal part of the digestive system with the primary function of re-absorption of water and inorganic salts. The mucosa surface is, and it has no intestinal villi or plicae. However, crypts of lieberkuhn are present and are usually longer and straighter than in the small intestines and the goblet cells compose more of the epithelial cells also than in the small intestines. In the submucosa, there is a considerable amount of fat. The appearance of the muscularity externa is also different from the small intestines. It is much thicker because faces are heavy and thicker and will require more force to push along (Cheng et al. 2010, 72). The circular muscles are important for preventing food in the large intestines from traveling backward while the longitudinal layer is essential for shortening the tract.