GIT Most Important Viva Questions with Answers
🔵 Theme 1 — Painful Swallowing
1. Why is the tongue important in swallowing?
Answer:
The tongue forms the food bolus and pushes it backward toward the oropharynx. Its intrinsic muscles change shape, while extrinsic muscles move it during chewing and swallowing. Posterior movement of the tongue initiates the pharyngeal phase of swallowing.
2. What is the clinical importance of motor nerve supply of the tongue?
Answer:
Most tongue muscles are supplied by the hypoglossal nerve. If this nerve is damaged, the tongue deviates toward the affected side due to unopposed action of the normal genioglossus. This is important in neurological examination.
3. Why are salivary glands important in digestion?
Answer:
Saliva lubricates food, helps bolus formation, and begins starch digestion through salivary amylase. It also protects oral mucosa by buffering acids and providing antibacterial substances like lysozyme and IgA.
4. Why does dry mouth cause difficulty in swallowing?
Answer:
Dry mouth reduces lubrication of food and mucosa. Without adequate saliva, bolus formation becomes difficult and swallowing becomes painful or uncomfortable. It also increases risk of oral ulcers and infections.
5. What is the functional role of the esophagus?
Answer:
The esophagus transports food from pharynx to stomach by coordinated peristalsis. It does not perform major digestion or absorption. Its sphincters prevent air entry and gastric reflux.
6. Why is lower esophageal sphincter important?
Answer:
The lower esophageal sphincter prevents reflux of acidic gastric contents into the esophagus. If it becomes weak, gastroesophageal reflux occurs, causing heartburn and esophagitis.
7. What is the difference between oropharyngeal and esophageal dysphagia?
Answer:
Oropharyngeal dysphagia occurs at the initiation of swallowing and may cause coughing or nasal regurgitation. Esophageal dysphagia occurs after swallowing and gives a sensation of food sticking behind the sternum.
8. Why is swallowing called a coordinated reflex?
Answer:
Swallowing involves oral, pharyngeal, and esophageal phases controlled by cranial nerves and swallowing centers in the brainstem. The reflex protects the airway while directing food into the esophagus.
🔵 Theme 2 — Pain Epigastrium
9. Why is the anterior abdominal wall clinically important?
Answer:
It protects abdominal organs and helps in respiration, coughing, vomiting, micturition, and defecation. Weak areas in the abdominal wall can lead to hernia formation, especially in the inguinal region.
10. What is the importance of peritoneum in abdominal pain?
Answer:
Parietal peritoneum is sensitive to pain, touch, and pressure, so irritation causes sharp localized pain. Visceral peritoneum is less sensitive and causes dull, poorly localized pain. This explains changing pain patterns in abdominal disease.
11. Why is epigastric pain common in stomach and duodenal disease?
Answer:
The stomach and duodenum are foregut derivatives, and foregut pain is referred to the epigastric region. Peptic ulcer, gastritis, and duodenitis commonly present with epigastric pain.
12. What is the functional importance of gastric motility?
Answer:
Gastric motility stores food, mixes it with gastric secretions, and slowly empties chyme into the duodenum. Controlled emptying allows proper digestion and prevents overload of the small intestine.
13. Why does the stomach not digest itself?
Answer:
The stomach is protected by the gastric mucosal barrier, mucus, bicarbonate, tight junctions, and good blood flow. These mechanisms protect mucosa from acid and pepsin. Breakdown of this barrier predisposes to ulceration.
14. What stimulates gastric acid secretion?
Answer:
Gastric acid secretion is stimulated mainly by acetylcholine, gastrin, and histamine. These act on parietal cells directly or indirectly. Acid secretion is inhibited by low pH, somatostatin, and prostaglandins.
15. Why is the duodenum commonly involved in peptic ulcer disease?
Answer:
The duodenum receives acidic chyme from the stomach. If acid load is excessive or bicarbonate protection is reduced, mucosal injury occurs. Helicobacter pylori and NSAIDs are common contributing factors.
16. Why do NSAIDs cause peptic ulcer?
Answer:
NSAIDs inhibit prostaglandin synthesis. Prostaglandins normally increase mucus and bicarbonate secretion and maintain mucosal blood flow. Their inhibition weakens mucosal protection and increases ulcer risk.
🔵 Theme 3 — Jaundice
17. Why is portal circulation important clinically?
Answer:
Portal circulation carries nutrient-rich blood from the gastrointestinal tract to the liver. In portal hypertension, pressure rises in this system, leading to varices, splenomegaly, and ascites.
18. What is the basic difference between hepatic and obstructive jaundice?
Answer:
Hepatic jaundice occurs due to liver cell damage causing impaired bilirubin handling. Obstructive jaundice occurs when bile flow is blocked after bilirubin conjugation. Obstructive jaundice usually causes pale stools and dark urine.
19. Why does obstructive jaundice cause pale stools?
Answer:
In obstruction, bile pigments cannot enter the intestine. Therefore, stercobilin formation is reduced. Since stercobilin gives stool its brown color, stools become pale or clay-colored.
20. Why does obstructive jaundice cause dark urine?
Answer:
Conjugated bilirubin is water-soluble. In obstructive jaundice, it refluxes into blood and is excreted in urine, making urine dark. Unconjugated bilirubin is not water-soluble and does not appear in urine.
21. What is the function of bile?
Answer:
Bile helps in emulsification and absorption of fats and fat-soluble vitamins. It also serves as a route for excretion of bilirubin, cholesterol, and some drugs. Bile salts are the active components in fat digestion.
22. Why is the gall bladder important?
Answer:
The gall bladder stores and concentrates bile. During a fatty meal, cholecystokinin causes gall bladder contraction and relaxation of sphincter of Oddi, allowing bile to enter the duodenum.
23. What is the importance of liver histology in function?
Answer:
Liver lobules are arranged so that blood flows from portal triads to central veins, while bile flows in the opposite direction. This arrangement allows hepatocytes to process nutrients, detoxify substances, and secrete bile efficiently.
24. Why does liver disease affect drug metabolism?
Answer:
The liver contains enzymes, especially cytochrome P450, that metabolize many drugs. In liver disease, metabolism decreases, causing drug accumulation and toxicity. Dose adjustment may be needed in hepatic impairment.
🔵 Theme 4 — Diarrhoea and Constipation
25. Why is the small intestine the main site of digestion and absorption?
Answer:
The small intestine has a large surface area due to folds, villi, and microvilli. It receives bile and pancreatic enzymes, and its mucosa contains transport mechanisms for nutrients, electrolytes, and water.
26. What is the function of villi and microvilli?
Answer:
Villi increase absorptive surface area, and microvilli form the brush border. Brush border enzymes complete digestion of carbohydrates and proteins. This structure is essential for efficient nutrient absorption.
27. Why does damage to intestinal villi cause malabsorption?
Answer:
Villus damage reduces surface area and brush border enzyme activity. This decreases absorption of nutrients, water, and electrolytes. Clinically, it can cause diarrhea, weight loss, and nutritional deficiencies.
28. What is the importance of intestinal motility?
Answer:
Intestinal motility mixes chyme with digestive secretions and moves it forward. Segmentation helps absorption, while peristalsis propels contents. Abnormal motility can cause diarrhea or constipation.
29. Why does diarrhea occur?
Answer:
Diarrhea occurs when intestinal water content increases due to increased secretion, decreased absorption, rapid motility, or osmotic load. It may be secretory, osmotic, inflammatory, or motility-related.
30. What is the difference between osmotic and secretory diarrhea?
Answer:
Osmotic diarrhea occurs due to non-absorbed solutes pulling water into the intestine and improves with fasting. Secretory diarrhea occurs due to active electrolyte and water secretion and usually continues even during fasting.
31. Why does constipation occur?
Answer:
Constipation occurs due to slow colonic transit, excessive water absorption, low fiber intake, dehydration, or defecation reflex problems. It results in hard stools and difficult passage.
32. Why is the appendix clinically important?
Answer:
The appendix has abundant lymphoid tissue and may become obstructed and inflamed, causing appendicitis. Pain may initially be periumbilical and later localize to the right iliac fossa due to parietal peritoneal irritation.
🔵 Theme 5 — Bleeding Per Rectum
33. What is the difference between small and large intestine function?
Answer:
The small intestine mainly digests and absorbs nutrients. The large intestine mainly absorbs water and electrolytes and forms feces. It also contains gut bacteria that produce some vitamins and ferment undigested material.
34. Why does bleeding per rectum occur in lower GI disease?
Answer:
Bleeding per rectum occurs when lesions in colon, rectum, or anal canal bleed. Causes include hemorrhoids, fissures, inflammatory bowel disease, polyps, and colorectal carcinoma. Bright red blood usually suggests distal source.
35. What is the importance of anal canal blood supply and venous drainage?
Answer:
The anal canal has systemic and portal venous connections. Dilatation of these venous plexuses can form hemorrhoids. This area is also important in portosystemic anastomosis.
36. Why is rectal examination important?
Answer:
Digital rectal examination can detect hemorrhoids, fissures, rectal masses, blood, and prostate enlargement in males. It is a simple but important clinical examination in bleeding per rectum and bowel symptoms.
37. What is the defecation reflex?
Answer:
Rectal distension activates stretch receptors and triggers parasympathetic reflexes. This increases rectal contraction and relaxes the internal anal sphincter. Voluntary relaxation of the external anal sphincter allows defecation.
38. Why does intestinal obstruction cause vomiting?
Answer:
Obstruction leads to accumulation of intestinal contents and distension. Distension activates visceral afferents and vomiting centers. The level of obstruction influences timing and nature of vomiting.
39. Why is colorectal carcinoma clinically important?
Answer:
Colorectal carcinoma may present with bleeding, altered bowel habits, anemia, weight loss, or obstruction. Early detection is important because prognosis improves greatly when diagnosed before spread.
40. Why does hindgut development matter clinically?
Answer:
Hindgut forms distal transverse colon, descending colon, sigmoid colon, rectum, and upper anal canal. Developmental errors may cause anorectal malformations or abnormal positioning of gut structures.
🔵 Theme 6 — Glucose Control
41. Why is glycolysis important?
Answer:
Glycolysis breaks glucose into pyruvate and produces ATP. It can occur without oxygen, making it important in red blood cells and exercising muscle. It also provides intermediates for other metabolic pathways.
42. What is the difference between glycolysis and gluconeogenesis?
Answer:
Glycolysis breaks glucose down to produce energy. Gluconeogenesis forms glucose from non-carbohydrate sources such as lactate, glycerol, and amino acids. Gluconeogenesis is important during fasting.
43. Why is the TCA cycle called the central metabolic pathway?
Answer:
The TCA cycle oxidizes acetyl-CoA from carbohydrates, fats, and proteins. It produces NADH and FADH₂, which enter oxidative phosphorylation to generate ATP. It also provides intermediates for biosynthesis.
44. Why does lack of oxygen reduce ATP production?
Answer:
Oxygen is the final electron acceptor in the electron transport chain. Without oxygen, oxidative phosphorylation stops, NADH accumulates, and ATP production falls. Cells then depend more on anaerobic glycolysis.
45. Why is the pentose phosphate pathway important?
Answer:
The pentose phosphate pathway produces NADPH and ribose-5-phosphate. NADPH protects cells from oxidative damage and is used in fatty acid synthesis. Ribose is needed for nucleotide synthesis.
46. Why are red blood cells dependent on the pentose phosphate pathway?
Answer:
Red blood cells need NADPH to maintain reduced glutathione, which protects hemoglobin and membrane from oxidative damage. Defect in this pathway, such as G6PD deficiency, can cause hemolysis.
47. Why is glycogen important?
Answer:
Glycogen is the storage form of glucose. Liver glycogen maintains blood glucose during fasting, while muscle glycogen provides energy for muscle activity. Glycogen metabolism is regulated by insulin, glucagon, and adrenaline.
48. What is the role of insulin and glucagon in glucose control?
Answer:
Insulin lowers blood glucose by increasing glucose uptake, glycogenesis, and lipogenesis. Glucagon raises blood glucose by stimulating glycogenolysis and gluconeogenesis. Their balance maintains blood glucose homeostasis.
🔵 Theme 7 — Obesity and Fat Metabolism
49. What is the difference between fatty acid synthesis and beta-oxidation?
Answer:
Fatty acid synthesis occurs mainly in the cytosol and stores excess energy as fat. Beta-oxidation occurs in mitochondria and breaks fatty acids into acetyl-CoA for energy production. Insulin favors synthesis, while fasting favors oxidation.
50. Why are ketone bodies formed during starvation or uncontrolled diabetes?
Answer:
During starvation or uncontrolled diabetes, fatty acid breakdown increases, producing excess acetyl-CoA. When the TCA cycle cannot handle all acetyl-CoA, the liver converts it into ketone bodies. Excess ketones may cause ketoacidosis.
51. Why is cholesterol important in the body?
Answer:
Cholesterol is a structural component of cell membranes. It is also a precursor for steroid hormones, bile acids, and vitamin D. However, excess LDL cholesterol increases risk of atherosclerosis.
52. What is the difference between LDL and HDL?
Answer:
LDL carries cholesterol from liver to tissues and is considered atherogenic when elevated. HDL carries cholesterol from tissues back to the liver for removal. Therefore, HDL is protective against atherosclerosis.
53. Why are bile acids important in lipid metabolism?
Answer:
Bile acids emulsify dietary fats and help absorption of fat-soluble vitamins. They are synthesized from cholesterol in the liver. Loss or deficiency of bile acids can cause fat malabsorption and steatorrhea.
54. Why is the urea cycle important?
Answer:
Protein breakdown produces ammonia, which is toxic especially to the brain. The urea cycle converts ammonia into urea in the liver for safe excretion by kidneys. Liver failure can cause hyperammonemia and encephalopathy.
55. Why do amino acid metabolism disorders cause neurological symptoms?
Answer:
Some amino acid metabolites are toxic to the brain when they accumulate. In disorders like phenylketonuria, failure to metabolize phenylalanine affects brain development. Early diagnosis and dietary control prevent complications.
56. How is obesity linked with metabolic disease?
Answer:
Obesity increases insulin resistance, dyslipidemia, fatty liver, and inflammation. Excess adipose tissue releases inflammatory mediators and free fatty acids. This increases risk of type 2 diabetes, hypertension, and cardiovascular disease.