Question

Submucosa is thickest in
A. Stomach
B. Oesophagus
C. Pancreas
D. Rectum

Answer 1

Hint: Submucosa is a layer that is found in various organs of our body like digestive, respiratory and reproductive organs. In helps easy movement gut tissues and aids in peristalsis.

Complete answer:
The wall of the alimentary canal consists of four layers namely – serosa, muscularis, submucosa and mucosa. Serosa is made up of thin mesothelium (epithelium of visceral organs) and is the outermost layer. Its epithelial layer is secretory in nature and has loose connective tissues that reduce friction in movement. Muscularis is made up of smooth muscles that are arranged into outer longitudinal and inner circular layers. It is responsible for peristaltic motions of the alimentary canal. Submucosa is thick, vascular, has glands embedded in it and nerve plexus. It has loose connective tissues that support the mucosa present below it. Mucosa is the innermost layer of the alimentary canal that is found surrounding the lumen. Food, digestive juices, mucus are passed through the lumen and mucosa comes in direct contact with them.
Submucosa is present throughout the alimentary canal starting from the oesophagus and ending in the rectum. Thickest layer of submucosa is found in the oesophagus to assist high peristaltic motions so that the food bolus can be easily transferred further.

Hence, the correct answer is option (B).

Additional information:
-Serosa provides partition between the abdominal cavity and internal organs.
-Serosa is absent in the oesophagus, but an outer layer called adventitia is present that sticks it to adjacent surfaces.
-Mucosa forms finger-like folds called villi in the small intestine.
-Mucosa forms crypts in between bases of villi present in small intestines called Crypts of Lieberkuhn and glands in the stomach called gastric glands.
-Submucosa that is present in duodenum (the first part of the small intestine) consists of glands.

Note: Submucosa is rich in large blood vessels, dense layers of connective tissues, lymphatics and nerves that extend into muscularis and mucosa layers. An enteric nervous plexus and Meissner’s plexus is also present in the form of tiny parasympathetic ganglia.