Question

Q1. Of the following which one causes the contraction of smooth muscles behind a bolus of food?

A. Release of Acetycholine by sensroy neruons of the enteric nervous system

B. Release of acetylcholine by motor neurons of the enteric nervous system

C. Release of nitric oxide by Interstital cells of cajal

D. The release of epinephrine from the sympathetic nervous system

Q2. H+ is secereted in the stomach by?

A. H+/K+ ATPase pump

B. H+/HCO3- antiport

C. H+/Cl- symport

D. H+ ATPase pump

Q3 Of the following which one drains secertions from the pancreas, gall bladder, and the liver into the duodenum?

A. Cyctic duct

B. Pancreatic duct

C. Common bile duct

Q4. HCO3- is secereted from pancreatic cells into the pancreaic duct by which of the follwoing apical membrane transporters?

A. HCO3-/Cl- antiport

B. HCO3-/Cl- ATPase pump

C. HCO3-/H+ antiport

Answer 1

1) Contraction of smooth muscles behind a bolus of food is caused by :-

B. Release of acetylcholine by motor neurons of the enteric nervous system.

Peristalsis is the smooth muscle contractions that propels foodstuffs distally through the esophagus and intestine. There are two mechanism possible :-

• One group of interneurons activates excitatory motor neurons above the bolus which contains acetylcholine stimulates the contraction of muscles above the bolus.

• Other group of interneurons inhibitory motor neurons that causes relaxation of smooth muscles below the bolus.

So the option (a) is incorrect since sensory neurons donot help in contractions.

Option (c) is also incorrect since Interstitial cells of cajal are the pace maker of the cell and don't release Nitric oxide.

Also the peristalsis is mainly controlled by enteric nervous system so (d) is incorrect.

Thus the correct answer is (b) Release of acetylcholine by motor neurons of the enteric nervous system.

2) H+ is secereted in the stomach by :-

A. H+/K+ ATPase pump

H+ secretions is an active process. Within the Parietal cells carbonic acid (H2CO3) is formed by H2O & CO2 with the help of carbonic anhydrase. It then dissociate into H+ & C03- . The H+/K+ ATPase pump uses energy to exchange potassium ions from the lumen with hydrogen ions in the parietal cells.

The other options are incorrect since these pumps donot secret H+ from parietal cells into lumen.

Thus the correct answer is (a) H+/K+ ATPase pump.

3) secretions from the pancreas, gall bladder, and the liver is drained into the duodenum by :-

(c) Common Bile duct

Common bile duct drains the secretions of Liver and gall bladder.

Pancreatic duct drains the secretions of pancreas.

Cystic duct carries secretions only from gall bladder.

The common bile duct joins the pancreatic duct to form Hepatopancreatic duct (also called as Ampulla of Vater) which drains into the second part of dueodenum through the opening Major deodenal papillae.

Since pancreatic duct joins the bile duct just prior to Ampulla of Vater so the common bile duct drains the secretions of pancreas, liver, gall bladder into dueodenum.

Thus the correct answer is (c) Common bile duct.

4) HCO3- is secereted from pancreatic cells into the pancreaic duct by :-

A. HCO3-/Cl- antiport

The HCO3-/Cl- antiport secrets HCO3 from pancreatic cells into pancreatic duct. HCO3 is exchanged with Cl- without use of ATP directly.

So the options (b) & (c) are incorrect.

Thus the Correct answer is (a) HCO3-/Cl- antiport.