Question

1. Which of the following descriptions is CORRECT?

i. The sacral nerves supply the smooth muscle of the GI tract from the last 1/3rd of the transverse colon through the rectum

ii. Between the two muscle layers of the muscularis externa, you can find the myenteric plexus

iii. Pepsinogen will become its active form as pepsin in a neutral environment

iv. The outermost layer (away from lumen) of jejunum is called serosa

v. In the arterial supply for the GI tract, superior mesenteric supplies esophagus to the upper duodenum

A. i, ii, iii

B. i, ii, iv

C. i, iv, v

D. i, iii, v

2. You CANNOT find which of the following choices in the colon?

A. pits

B. columnar absorptive cells

C. villi

D. goblet cells

3. Sympathetic nerves innervate smooth muscle contractions in the GI tract, while parasympathetic nerves control both secretions in the mucosa layer and the smooth muscle within vasculature of the GI tract.

A. True

B. False

Answer 1

1) answer is B. i,ii,iv

Explanation- iii is wrong because pepsinogen becomes active in acidic pH in stomach provided by HCl. v is wrong because superior mesenteric artery supplies lower part of duodenum till 2/3rd of transverse colon and pancreas.

2) The correct answer is C. Villi

Explanation- villi is present in the small intestine for increasing the surface area for absorption. It is absent in large intestine.

3) False

Explanation- sympathetic nervous generally have an inhibitory effect on GI smooth muscles. Whereas parasympathetic nerves cause contractions of smooth muscle of GI tract. Parasympathetic system also increases secretions in GIT.

* Note- the sentence in the last questions seems to have little error.Hope the explanation given helps. For any doubt,post a comment.