Question

which of the following features is found only in the stomach and not in the rest of the digestive tract?

a) hausta

b) skeletal muscle

c) plicae circularis

d) adventitial

e) oblique layer

Answer 1

Answer) option e - oblique layer

Explanation -

Normally, the muscularis externa of the digestive tract consists of 2 layers of smooth muscle - inner circular and outer longitudinal layers.

But in the stomach, muscularis externa is composed of three layers of smooth muscles - inner oblique, middle circular and outer longitudinal layers.

This oblique layer helps in digestion of food by churning and mixing the food with digestive juices and digestive enzymes.

Other options are incorrect -

Option A is incorrect - As haustra are present in large intestine.

Haustra also known as sacculations. These are series of pouches/dilatation in the wall of caecum and colon of the large intestine between the teniae coli.

The haustra are responsible for the characteristic puckered appearance of the large intestine.

Option B is incorrect - As in digestive tract, muscularis externa consists of smooth muscle.

But in mouth, pharynx and upper part of oesophagus of the digestive tract, muscularis externa is composed of striated muscle fibers i.e skeletal muscles which helps in swallowing of food.

Option C is incorrect - As plica circularis is present in small intestine.

Plica circularis are the circular folds of the mucosa, which are permanent and are not obliterated by distension, which are present in jejunum and ileum of the small intestine.

These folds helps in digestion and absorption of nutrients.

Option D is incorrect - As adventitia layer (also known as serous layer) is present in every part of the digestive tract.

It is the outer most layer of the digestive tract and it covers the muscularis externa layer.