Question

Intestine absorbs digested food materials. What type of epithelial cells are responsible for that
(a) Striated squamous epithelial
(b) Columnar epithelium
(c) Spindle fibers
(d) Cuboidal epithelium

Answer 1

Hint: Single layer of cells which are tall and wide that lines the alimentary canal that help in secretion of digestive enzymes, mucus and gastric acid in the stomach .

Complete answer:
The innermost layer of the alimentary canal lumen is the mucosa. The mucosa in the small intestine forms small folds called villi. Villi are lined by columnar epithelial cells that produce numerous microscopic projections called microvilli. They increase the surface area for the absorption of digested food.

Additional Information:Alimentary canal in humans starts from the esophagus to the rectum. It is lined by four layers namely serosa, muscularis externa, and mucosa
- The outermost layer that is made up of thin mesothelium is called serosa. The mesothelium is attached with some connective tissue
- The second layer is muscularis externa that is made up of smooth muscle. It is divided into two layers, outer longitudinal and inner circular muscles. An oblique layer may be present in some layers such as the stomach.
- The third layer is the submucosa that is formed by loose connective tissue. It connects nerves, blood vessels, and lymph vessels.
- Burner’s glands in the duodenum present in the submucosa layer secrete mucus.
- Mucosa is the fourth layer of the alimentary canal and it is the innermost layer. The mucosa in the stomach forms irregular folds called gastric rugae.
The mucosa in the small intestine forms several small folds called villi which contain microvilli made up of columnar epithelium that increases the surface area of absorption.
So, the correct answer is 'Columnar epithelium'.

Note: Microvilli present on the villi of the small intestine gives a brush border appearance.
The plasma membrane of microvilli has enzymes such as disaccharides. They are called brush border enzymes.
Each villus has a network of capillaries. Lacteal is the largest lymph capillary.