Weekly Year 2: GIT Physiology Exam - April 17, 2026 (Section

Question 1

Which tissue layer provides for primary digestive motility?

Accepted Answer

Muscularis externa — The muscularis externa, consisting of inner circular and outer longitudinal smooth muscle layers, is responsible for the segmental contractions and peristaltic movements of the GI tract.

Question 2

Which statement about bile is true?

Accepted Answer

Bile salts are essential for the emulsification of dietary fats — Bile does not contain enzymes; its primary role in digestion is the emulsification of fats via bile salts to increase the surface area for lipase.

Question 3

Which statement regarding the swallowing reflex is FALSE?

Accepted Answer

The glottis opens to allow food into the larynx — During swallowing, the glottis closes and the epiglottis tips backward to prevent food from entering the larynx and trachea.

Question 4

Regarding tonic contractions in the GIT, which of the following is FALSE?

Accepted Answer

They are associated with the Basic Electrical Ritual (BER) slow waves — Tonic contractions are often independent of the rhythmic slow waves (BER) that characterize phasic contractions.

Question 5

Which of the following is characteristic of the segmenting movements in the small intestine?

Accepted Answer

They are responsible for mixing chyme with digestive enzymes — Segmentation is the primary mixing movement of the small intestine, alternating contraction and relaxation of adjacent segments.

Question 6

Secreation of saliva increases in all of the following EXCEPT:

Accepted Answer

Sympathetic dominance (stress) — Strong sympathetic stimulation during stress typically results in a dry mouth (xerostomia) by producing a small amount of viscous saliva and causing vasoconstriction.

Question 7

Defecation is a reflex action that is:

Accepted Answer

Initiated by distension of the rectum — The presence of feces in the rectum causes distension, which triggers the intrinsic and parasympathetic defecation reflexes.

Question 8

In the stomach, the alkaline tide refers to:

Accepted Answer

Efflux of bicarbonate into the blood during HCl secretion — During HCl secretion by parietal cells, bicarbonate is exported across the basolateral membrane into the blood in exchange for chloride.

Question 9

Intestinal secretions (Succus entericus) primarily contain:

Accepted Answer

Water, electrolytes, and mucus — Intestinal juice is mainly a watery fluid containing electrolytes and mucus; digestive enzymes are mostly located on the brush border, not secreted into the lumen.

Question 10

A 55-year-old man with chronic alcohol consumption shows destruction of gastric glands. This predisposes him to:

Accepted Answer

Iron deficiency and Pernicious anemia — Loss of gastric glands (atrophy) reduces Intrinsic Factor (causing B12 deficiency/pernicious anemia) and HCl (required for iron solubility/absorption).

Question 11

Which of the following gastrointestinal hormones is secreted by 'I' cells in the duodenum and stimulates gallbladder contraction?

Accepted Answer

Cholecystokinin (CCK) — CCK is secreted by I cells in response to fatty acids and amino acids, stimulating gallbladder contraction and pancreatic enzyme secretion.

Question 12

Vasoactive Intestinal Peptide (VIP) causes:

Accepted Answer

Relaxation of GI sphincters — VIP is an inhibitory neurotransmitter in the GI tract that relaxes smooth muscle/sphincters and stimulates intestinal fluid secretion.

Question 13

The primary stimulus for the release of Secretin is:

Accepted Answer

Acidic chyme (pH < 4.5) in the duodenum — Secretin is released by S cells in response to acidic chyme, stimulating the pancreas to secrete bicarbonate-rich fluid.

Question 14

Inhibition of the myenteric (Auerbach’s) plexus leads to which of the following?

Accepted Answer

Decreased GI motility and propulsion — The myenteric plexus primarily controls gut motility; inhibiting it results in decreased peristalsis.

Question 15

Stimulation of the submucosal (Meissner’s) plexus results in an increase in:

Accepted Answer

Glandular secretion and local blood flow — The submucosal plexus primarily regulates secretion, absorption, and local blood flow within the gut wall.

Question 16

About the GIT hormones affecting gastric function, which is correct?

Accepted Answer

GIP (Gastric Inhibitory Peptide) stimulates insulin release — GIP, also known as Glucose-dependent Insulinotropic Peptide, stimulates insulin release from the pancreas in response to glucose.

Question 17

Which of the following is true regarding Gastrin?

Accepted Answer

Produced by G-cells in the gastric antrum — Gastrin is produced by G-cells in the antrum; it is stimulated by peptides and vagal activity, and increases LES tone.

Question 18

Which hormone is responsible for the 'Migrating Motor Complex' (MMC) during fasting?

Accepted Answer

Motilin — Motilin is the primary hormone that initiates the MMC waves every 90 minutes during the interdigestive state.

Question 19

Water transport in the intestine is:

Accepted Answer

Passive, following the osmotic gradient created by solute absorption — Water moves passively (osmosis) across the intestinal mucosa following the absorption of solutes like Na+ and glucose.

Question 20

Which of the following enzymes is responsible for the activation of trypsinogen to trypsin?

Accepted Answer

Enterokinase (Enteropeptidase) — Enterokinase, located on the duodenal brush border, converts trypsinogen to active trypsin, which then activates other proteases.

Question 21

Fat digestion and absorption involve:

Accepted Answer

Formation of chylomicrons within enterocytes — Fatty acids and monoglycerides are re-esterified into triglycerides in the cell and packaged into chylomicrons for transport into lymphatics.

Question 22

Which statement about dietary fiber is most correct?

Accepted Answer

It provides bulk to the stool and can be fermented by colonic bacteria — Fiber adds bulk to stool, decreases transit time, and acts as a substrate for bacterial fermentation in the colon.

Question 23

Regarding stomach lining cells, parietal cells secrete:

Accepted Answer

Intrinsic Factor and HCl — Parietal (oxyntic) cells are responsible for the production of gastric acid (HCl) and Intrinsic factor.

Question 24

Which single statement about the oral phase of digestion is INCORRECT?

Accepted Answer

It is entirely under hormonal control — The oral phase and salivary secretion are primarily under neural (autonomic) control, not hormonal control.

Question 25

What is the primary function of colonic microbiota?

Accepted Answer

Synthesis of Vitamin K and certain B vitamins — Gut bacteria play a vital role in synthesizing vitamins (K, B12, Thiamine) and fermenting undigested carbohydrates.

Question 26

Which of the following inhibits gastric acid secretion?

Accepted Answer

Enterogastric reflex (distension of duodenum) — The enterogastric reflex, triggered by acid or distension in the duodenum, inhibits gastric motility and gastric acid secretion (the 'brakes').

Question 27

The 'receptive relaxation' of the stomach is mediated by:

Accepted Answer

Vagovagal reflex — Receptive relaxation allows the stomach to accommodate food without a large increase in pressure and is mediated by a vagovagal reflex using VIP/NO.

Question 28

Bicarbonate secretion in the pancreas is stimulated primarily by:

Accepted Answer

Secretin — Secretin is the 'nature's antacid' hormone, stimulating the ductal cells of the pancreas to release bicarbonate.

Question 29

Iron absorption in the small intestine is enhanced by:

Accepted Answer

Ascorbic acid (Vitamin C) — Vitamin C reduces ferric iron (Fe3+) to ferrous iron (Fe2+), which is more easily absorbed.

Question 30

The primary site for the absorption of bile salts is the:

Accepted Answer

Terminal Ileum — Bile salts undergo enterohepatic circulation and are actively reabsorbed in the terminal ileum.

Question 31

Vitamin B12 absorption requires:

Accepted Answer

Intrinsic Factor and a healthy terminal ileum — B12 binds to intrinsic factor in the stomach and the complex is absorbed in the terminal ileum.

Question 32

Which of the following results in increased gastric emptying?

Accepted Answer

Increased distension of the stomach — Gastric distension increases motility and emptying via local reflexes and gastrin; duodenal factors (fat, acid, osmolarity) inhibit emptying.

Question 33

The migrating motor complex (MMC) is inhibited by:

Accepted Answer

Feeding — The MMC is a fasting state phenomenon. Upon ingestion of food, the MMC is abolished and replaced by a fed-state motility pattern.

Question 34

Which statement about pancreatic enzyme secretion is correct?

Accepted Answer

CCK is the most potent stimulus for acinar cell secretion — CCK stimulates the acinar cells to release digestive enzymes; pancreatic proteases are secreted as inactive zymogens.

Question 35

Lactose intolerance is caused by a deficiency in:

Accepted Answer

Lactase — Lactase is the brush-border enzyme that breaks down lactose into glucose and galactose; its deficiency leads to osmotic diarrhea.

Question 36

Which of the following is an effect of Somatostatin in the GI tract?

Accepted Answer

Inhibits release of all GI hormones — Somatostatin is a universal inhibitory paracrine/hormone in the GIT, reducing acid secretion and hormone release.

Question 37

The swallowing center is located in the:

Accepted Answer

Medulla Oblongata — The coordination of the complex swallowing reflex occurs in the swallowing center of the medulla and lower pons.

Question 38

Which of these is NOT a function of the liver?

Accepted Answer

Production of digestive enzymes like Trypsin — Trypsin and other digestive enzymes are produced by the exocrine pancreas, not the liver.

Question 39

The primary role of the Haustral contractions in the large intestine is:

Accepted Answer

Mixing and slow movement to facilitate water absorption — Haustrations are slow segmenting movements in the colon that help mix the contents and optimize water/electrolyte absorption.

Question 40

Fat-soluble vitamins (A, D, E, K) are absorbed via:

Accepted Answer

Simple diffusion after being incorporated into micelles — As they are lipophilic, these vitamins are packaged into micelles with bile salts and fatty acids to be absorbed by simple diffusion.

Question 41

Which of the following is the hallmark of the 'Cephalic Phase' of gastric secretion?

Accepted Answer

Stimulation of acid secretion by the thought, smell, or taste of food — The cephalic phase is mediated by the vagus nerve in response to sensory stimuli before food enters the stomach.

Question 42

What is the function of the Law of the Gut (Peristaltic Reflex)?

Accepted Answer

Contraction behind the bolus and relaxation ahead of it — The peristaltic reflex ensures one-way movement by contracting the proximal smooth muscle and relaxing the distal smooth muscle.

Question 43

Which cell type in the gastric glands secretes Pepsinogen?

Accepted Answer

Chief (Zymogenic) cells — Chief cells produce pepsinogen, which is converted to active pepsin in the presence of low pH (HCl).

Question 44

The gastrocolic reflex results in:

Accepted Answer

Mass movements in the colon following food entering the stomach — The gastrocolic reflex is a long-arc reflex where stomach distension stimulates mass movements in the colon.

Question 45

Secondary peristalsis in the esophagus is initiated by:

Accepted Answer

Distension of the esophagus by a retained bolus — Secondary peristalsis is a local reflex used to clear the esophagus of food not moved by the primary wave.

Question 46

Which of the following is TRUE about the absorption of glucose?

Accepted Answer

It is co-transported with Sodium (SGLT-1) — Glucose and galactose are absorbed via secondary active transport using the SGLT-1 carrier, which depends on the sodium gradient.

Question 47

Chloride ions are secreted into the intestinal lumen primarily through:

Accepted Answer

CFTR channels — The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is the main channel for cAMP-mediated chloride secretion.

Question 48

Which of the following best describes the function of Mucin in the GIT?

Accepted Answer

Lubrication and protection of the mucosa — Mucin (in mucus) provides a protective barrier against acid and abrasion, and facilitates the passage of the bolus.

Question 49

What is the 'Ileal Brake'?

Accepted Answer

The inhibition of upper GI motility by presence of nutrients in the distal ileum — The ileal brake is a feedback mechanism where undigested nutrients (especially fat) reaching the ileum slow down gastric emptying and small bowel transit.

Question 50

During the intestinal phase of gastric secretion, the presence of slightly digested proteins in the duodenum:

Accepted Answer

Briefly stimulates gastric acid via intestinal gastrin release — Initially, the intestinal phase can slightly stimulate the stomach via enteric gastrin, though the inhibitory 'enterogastric' signals soon dominate.

Weekly Year 2: GIT Physiology Exam - April 17, 2026 (Section

Questions, Answers & Explanations