Question

Lining of the intestine of man is _________
A. Brush bordered
B. Ciliated
C. Non- Keratinised
D. Keratinised

Answer 1

Hint: The human digestive system starts with the mouth and ends in the rectum. In between there are a lot of organs such as buccal cavity, oesophagus, stomach, small intestine and large intestine. The innermost lining of the digestive tract is known as mucosa made up of columnar epithelial cells. It is modified in different regions to aid the process of digestion.

Complete answer:
The outer surface of the inner lining of the intestine is made up of columnar epithelial cells. This brush border appearance is due the presence of microvilli. The microvilli are responsible for the absorption of digested food particles such as amino acids, glucose and vitamins and minerals through the blood vessel present in the microvilli. The digested fat that forms fatty acids and glycerol are absorbed by the lacteal ducts present in the microvilli. The main function of microvilli is to increase the surface area for absorption so that the absorption can take place smoothly. All this happens in the small intestine, which is $6.5$ m long. The cells of the lining folded to form villi, have microscopic projections called microvilli. Increase in surface area for absorption in turn increases the efficiency of absorption.

So, Lining of the intestine of man is brush bordered, made up of columnar epithelial cells Therefore the correct answer is option A.

Note:
The modification of the mucosa layer is very important for proper digestion to take place. In the stomach the columnar epithelial cells are modified to rugae for proper churning and mixing of food. In the intestine, the cells are modifying to villi, giving an appearance of brush border, which helps in increasing the surface area for absorption.