GIT Physio

Question 1

Sectioning of vagal nerve supply to stomach will cause all of the following EXCEPT:
A. Decreased gastric mucus secretion
B. Decreased gastric acid secretion
C. Decreased gastric emptying
D. Decreased distension of the stomach
E. Decreased mucosal growth

Answer 1

C. a plain vagotomy is not very realistic in modern times and it is more likely to be a case of highly selective vagotomy. This refers to denervation of only those branches supplying the lower esophagus and stomach (leaving the nerve supply of the antrum and pylorus in place to ensure the emptying function of the stomach remains intact). It is one of the treatments of peptic ulcer.

Question 2

Drinking 500ml of water ONLY will lead to the following:
A. Absorption via paracellular route in small intestines only
B. Absorption in large intestine
C. Absorption dependent on sodium and glucose
D. Release of ADH from hypothalamus
E. Decreased intestinal transit

Answer 2

C. Water movement follows solutes, hence that is why oral rehydration therapy using glucose saved 50 million lives. Making patients drink lots of water alone does not really help with water absorption.

Question 3

A lipase inhibitor can cause the following symptoms except:
A. Weight loss
B. Diarrhea
C. Vitamin D deficiency
D. Loss of bile salts
E. Foul smelling stools

Answer 3

D. Lipase inhibitors reduce the gastrointestinal absorption of fat by preventing fat digestion. Hence, this can cause weight loss (option A), diarrhoea (option B), steatorrhea (option E, bacterial fermentation of fat), and vitamin D deficiency (option C) because fat soluble vitamins (A,D,E,K) are absorbed together with fat. The mechanism by which lipase inhibitors can cause diarrhea is primarily related to the presence of unabsorbed fats in the gastrointestinal tract. When dietary fats are not broken down and absorbed properly due to lipase inhibition, they remain undigested in the intestines and can exert osmotic effects.

Question 4

Complete obstruction of the common bile duct leads to all of the following EXCEPT:
A. Jaundice
B. Raised conjugated bilirubinaemia
C. Pale stools
D. Bilirubin in the urine
E. Urobilirubin the urine

Answer 4

E. We do not use the term urobilirubin (option E). Options A-D are classic symptoms of post-hepatic jaundice.

Question 5

Total gastrectomy can result in all the following EXCEPT:
A. Bacterial overgrowth
B. Loss of weight
C. Vitamin B12 deficiency
D. Diarrhea
E. Carbohydrate malabsorption

Answer 5

E. Gastrectomy results in loss of gastric acids which have bacteriostatic effect (causing bacterial overgrowth, option A), reduced production of intrinsic factor (causing B12 deficiency, option C). Diarrhoea (option D) may result because the food passes too quickly through the colon, as there is no pyloric sphincter to regulate gastric emptying, causing gastric dumping syndrome. Without a stomach, this limits the amount of food we can eat by making us feel full after eating small amounts of food, causing weight loss (option B); vertical sleeve gastrectomy is a method to help obese patients lose weight. Option E is the answer because carbohydrate digestion and absorption occurs mostly in the small intestines.

Question 6

With reference to gastric function,
a. The average meal has moved from the stomach after ½ hour
b. Contractility is augmented by sympathetic stimulation
c. When the quantity of ingested material increases, the intragastric pressure increases
d. The longitudinal muscle coat has a basic electrical rhythm
e. Histamine inhibits the production of gastric acid

Answer 6

D. 12. Option A is wrong because 2-3h is required for stomach to empty an average meal. Option B is wrong because contractility or gastric churning is stimulated by parasympathetics. Option C is wrong because receptive and adaptive relaxation of stomach occurs to accommodate entry of food, minimizing any rise in intragastric pressure. Option E is wrong because histamine, secreted by ECL cells, stimulates HCl secretion by parietal cells.

Option D is correct as the interstitial cells of Cajal are specialized pacemaker cells located in the wall of the stomach, small intestine, and large intestine. The cell membranes of the pacemaker cells undergo a rhythmic depolarization and repolarization, creating a slow wave known as a Basic Electrical Rhythm, and it is transmitted to the smooth muscle cells. The frequency of these depolarizations in a region of the GI tract determines the possible frequency of contractions.

Question 7

Which following hormone stimulates pancreatic HCO3- secretion in the presence of decreased secretion?
a. gastrin
b. VIP
c. GIP
d. CCK
e. Somatostatin

Answer 7

B. Vasoactive Intestinal Peptide (VIP, Option B) is a neuropeptide; its role in the intestine is to greatly stimulate secretion of water and electrolytes, stimulate pancreatic bicarbonate secretion, and inhibiting gastrin-stimulated gastric acid secretion.

Question 8

Which of the following is true:
a. 95% of bile pigments secreted by the liver is absorbed in the gut
b. most of the water absorbed in GIT is derived from dietary intake
c. CCK neutralizes the small intestine of acid from the stomach
d. Cl- is secreted into the bile in the gall bladder
e. malabsorption of lipids will lead to failure of pancreatic secretion

Answer 8

A. Option A (refer to q14,15) Enterohepatic circulation occurs for both bile acids and bile pigments. Bile pigments refer to colored compounds from the breakdown of haem - bilirubin, urobilin, stercobilin etc. Option B is wrong because most of the absorbed fluids are secretions (e.g. bile, pancreatic juice, saliva, gastric juice).

Question 9

. Parasympathetic blockade of the GIT leads to which of the following
A. abdominal pain
B. increase intestinal transit time
C. increase bile secretions
D. increase fecal water loss
E. increase mucous secretion

Answer 9

B. Parasympathetics regulate intestinal motility in various ways. For example, ileal peristalsis intensifies after a meal, emptying ileal contents into the cecum so as to make way for the new meal (gastroileal reflex). Hence, parasympathetic blockade will increase the time taken for food to travel through the intestines (option B).

Question 10

In pernicious anaemia, an autoimmune process destroys the “proton pump” and the parietal cells. Which one of the following observations is TRUE:
a. Acid secretion is normal
b. Absorption of intrinsic factor is affected
c. Blood gastrin level is raised
d. Blood histamine level is raised
e. Blood H+ is raised

Answer 10

C. Acid usually inhibits gastrin relase. With less acid, more gastrin is produced

Question 11

In the regulation of pancreatic secretion:
a. Low duodenal pH stimulates alkaline secretion
b. Secretin stimulates enzyme secretion
c. CCK stimulates HCO3 secretion
d. Gastrin stimulates acid secretion
e. Enterokinase stimulates protease secretion

Answer 11

A. Acidic chime entering duodenum triggers secretin release by S cells. Secretin stimulates ductal cells of pancreas to secrete isosmotic HCO3- and water to neutralize stomach acid.

Question 12

Entry of acidic chyme into the duodenum causes all the following except
a. Release of secretin
b. Contraction of sphincter of oddi
c. Contraction of gall bladder
d. Increased pancreatic secretion
e. Inhibition of gastric emptying

Answer 12

B. Acidic chyme entering duodenum triggers secretin release (option A) by S cells. This increases pancreatic secretion of alkaline pancreatic juice (option D), and also slows gastric emptying (option E) via duodenogastric reflex. The hormone cholecystokinin (CCK) stimulates contractions in the smooth muscle of the gallbladder (option C), and also causes relaxation of the sphincter of Oddi, allowing bile release into the duodenum. Hence option B is the answer

Question 13

The following are true of bile salts except:
a) Synthesized from cholesterol
b) Converted by intestinal bacteria to secondary bile salts
c) Acts as “detergent” in gut
d) Vast majority absorbed in proximal small intestine
e) Causes itch in skin during obstructive jaundice

Answer 13

Option D is wrong as most bile salts are reabsorbed in the terminal ileum.

Question 14

Which of the following induces contraction of gallbladder smooth muscle?
a. Secretin.
b. Cholecystokinin
c. Serotonin
d. Gastrin
e. Somatostatin

Answer 14

B. CCK stimulates contraction of gall bladder smooth muscle (option B) to increase secretion of bile into duodenum, in response to more fat and protein entering the duodenum.

Question 15

High doses of antibiotics can destroy the bacterial flora of the large intestine. This can result in impaired:
a. Absorption of protein
b. Blood coagulation
c. Bone resorption
d. Respiratory control

Answer 15

B. . Bacterial flora in large intestines produce vitamin K, which is needed to produce clotting factors (option B).

Absorption of protein (option A) occurs in small intestines via Na+ dependent cotransporters.

Question 16

The following is a major factor in protecting the duodenal mucosa from acid secretions from the stomach
A) Alkaline bile secretions
B) Gastrin release
C) Duodenal bicarbonate secretions
D) Pancreatic bicarbonate secretions
E) Duodenal mucosal permeability

Answer 16

D. Between option C and D, option D is the better choice because a larger volume of pancreatic bicarbonate secretions is produced to neutralize the acid from the stomach. It is also more responsive and can be stimulated by CCK and secretin, hence it is the more “major” factor.

Question 17

Which of the following is not a component of gastric juice?
a. Hydrochloric acid
b. Mucus
c. Pepsin
d. Amylase
e. Water

Answer 17

D. Amylase (option D) is a component of saliva, but not gastric juice. The other options are all components of gastric juice

Question 18

Pepsinogen is synthesized and released by which of the following?
a. Parietal cells
b. Enteroendrocrine cells
c. Paneth cells
d. Chief cells
e. Pancreatic acinar cells

Answer 18

D. Chief cells (option D) in the gastric glands of the stomach secrete pepsinogen, which is converted to pepsin by stomach acid.

Question 19

Which of the following pairs of hormones are mainly involved in controlling pancreatic exocrine secretions?
a. Insulin and glucagon
b. Cholecystokinin and secretin
c. Somatostatin and gastrin
d. Motilin and serotonin
e. Glucagon and somatostatin

Answer 19

B. Pancreatic exocrine secretions include bicarbonate from ductal and centroacinar cells (stimulated by secretin) and digestive enzymes from basophilic cells (stimulated by CCK).

Question 20

Which of the following is true of electrolyte absorption?
a. Sodium ion absorption is coupled to glucose and amino acid uptake
b. Potassium can diffuse through the intestinal epithelium
c. Vitamin D is necessary for calcium absorption
d. All of the above

Answer 20

D. Option A: true, Na+ dependent cotransporters; this is the fundamental basis of oral rehydration therapy.
Option B: true, K+ diffuses down the electrochemical gradient through gap junctions in small intestines.
Option C: vitamin D increases the number of calcium binding protein on intestinal epithelial cells, enabling the cells to actively transport more Ca2+ from the intestine across the intestinal mucosa into the blood.
Option D is thus correct

Question 21

A perimenopausal woman was seen in the clinic because of excessive menstrual bleeding. Investigations revealed that she had a hypochromic microcytic anaemia. She was treated orally with iron supplements and her condition improved with resolution of the anaemia. Which of the following statements is TRUE?
A) Iron is almost completely absorbed in the small intestines
B) Iron is absorbed via the ferroportin transporter on the intestinal epithelial cells
C) Iron is absorbed in its ferric form in the small intestine
D) Iron is bound in ferric form as ferritin in storage tissue
E) Iron is transported in the blood as haptoglobulin

Answer 21

D. Iron is absorbed in ferrous form (Fe2+) via Divalent Metal Transporters. Absorption is regulated depending on level of iron stores in body. Iron is stored in ferric form (Fe3+) as ferritin (option D). Haptoglobin is a protein that binds free hemoglobin in the blood (which may be raised due to hemolytic anemia) to inhibit its oxidative activity.

Question 22

If the whole colon is removed, what physiological function of the colon would be lost as well?
A) Net absorption of K+
B) Net absorption of HCO3-
C) Net secretion of H+
D) Bile acid stimulated water absorption
E) Short chain fatty acid stimulated water absorption

Answer 22

E. Option A: Under normal circumstances, net secretion of K+ occurs in the colon.
Option B: Under normal circumstances, net secretion of HCO3- occurs in the colon.
Option C: false
Option D: bile acids are reabsorbed in terminal ileum, not colon
Option E: SCFAs produced by colonic bacteria are absorbed directly into enterocytes

Question 23

In absorption of nutrients from the small intestine
A) Brush border lipases enhances digestion of fats for absorption
B) Fructose absorption is dependent on Na+ absorption
C) Short peptides are absorbed via transporters
D) Amino acids are absorbed by passive diffusion
E) Calcium absorption is dependent on chloride absorption

Answer 23

C. Option C: short peptides (dipeptides or tripeptides) can be absorbed via Na+ dependent cotransporters
Option A: lipases are not on the “brush border”
Option B: GLUT5 is a fructose transporter on the apical surface of enterocytes which allows for facilitated diffusion of fructose
Option D: Amino acids are absorbed by active transport
Option E: Ca2+ absorption is dependent on vitamin D

Question 24

An old man had pylorus and antrum of his stomach removed because of a tumour. Which of the following would happen?
A) Absence of gastric accommodation
B) Gastric acid secretion will be absent
C) Fluid efflux into intestinal lumen will be increased
D) Constipation would be frequent
E) Increased intestinal transit time

Answer 24

Option C is the best answer because removal of pylorus will result in loss of pyloric sphincter action, so increased “gastric dumping” occurs

Question 25

Bilateral vagotomy was used for treatment of peptic ulcer. The following will be the physiologic consequences except:
A. Decreased gastric secretion
B. Decreased gastric volume after food
C. Decreased gastric secretion
D. Decreased intestinal transit time
E. Decreased colonic filling

Answer 25

D. Without vagal stimulation, there is a lack of parasympathetic tone, thus motility is decreased, and intestinal transit time should be INCREASED (option D is the answer).

Question 26

Administration of parasympathetic agonist (cholinergic) effects:
A. dry mouth
B. difficulty in swallowing
C. constipation
D. abdominal pain
E. tachycardia

Answer 26

D. (due to colicky abdominal pain from hyperactive bowel)

Question 27

What will be observed when there is total obstruction of common bile duct
A. Unconjugated hyperbilirubinemia
B. Stercobilin in feces
C. Secretory diarrhoea
D. Unconjugated bilirubin in urine
E. Increase bile salts in blood

Answer 27

E. . Obstruction of bile duct will result in bile salts being unable to be secreted into the duodenum. The accumulation of bile salts in the biliary system will eventually cause some bile salts to enter the blood stream, thus option E is the answer.

Question 28

Sight and smell will stimuate which of the following EXCEPT
A. appetite
B. salivary secretion
C. gastric secretion
D. pancreatic endocrine secretion
E. ileogastric reflex

Answer 28

E. Option E: as its name suggests, the ileogastric reflex refers to inhibition of gastric motility and emptying by distension of the ileum

Question 29

A doctor suspects a patient of having familial LPL deficiency. Elevation of which of the following particles will confirm his diagnosis?
a. LDL
b. Chylomicron Remnants and IDL
c. HDL
d. VLDL
e. Chylomicrons

Answer 29

E. Lipoprotein lipase (LPL) is a key enzyme required for the hydrolysis of TGs in chylomicrons. Chylomicrons is “highest” in the chain of structures