Weekly Year 2: GIT Physiology Exam - April 3, 2026 (Section

Question 1

Regarding gastrointestinal hormones, which of the following is true?

Accepted Answer

Secretin stimulates the secretion of bicarbonate-rich pancreatic juice — Secretin is released from S cells in the duodenum in response to low pH and stimulates the pancreas to release bicarbonate.

Question 2

Vasoactive Intestinal Peptide (VIP) causes which of the following effects?

Accepted Answer

Relaxation of intestinal smooth muscle and sphincters — VIP is an inhibitory neurotransmitter in the GIT that causes smooth muscle relaxation and stimulates intestinal secretion.

Question 3

Stimulation of Gastrointestinal Secretion is primarily mediated by:

Accepted Answer

Enteric nervous system and parasympathetic activation — Parasympathetic (vagal) and enteric nervous system activation are the primary neural stimulators of GIT secretion.

Question 4

The hormone Secretin is primarily released in response to:

Accepted Answer

Acidic chyme (pH < 4.5) in the duodenum — The primary stimulus for secretin release is the presence of hydrochloric acid in the duodenum.

Question 5

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

Accepted Answer

Decreased gastrointestinal motility — The myenteric plexus primarily controls GIT motility; its inhibition results in decreased motor activity.

Question 6

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

Accepted Answer

Glandular secretion and local blood flow — The submucosal plexus regulates local secretion, absorption, and local blood flow.

Question 7

Regarding GIT hormones affecting gastric function, which statement is true?

Accepted Answer

Cholecystokinin (CCK) slows gastric emptying — CCK inhibits gastric emptying to ensure adequate time for fat digestion in the duodenum.

Question 8

Cholecystokinin (CCK) is responsible for:

Accepted Answer

Contraction of the gallbladder and relaxation of the Sphincter of Oddi — CCK coordinates the delivery of bile into the duodenum by contracting the gallbladder and relaxing the sphincter.

Question 9

The major factor that stimulates the release of Secretin into the bloodstream is:

Accepted Answer

Hydrochloric acid in the duodenum — Secretin is the 'nature's antacid' released when the duodenum detects low pH.

Question 10

It is known that Gastrin:

Accepted Answer

Is secreted by G cells in the gastric antrum and duodenum — Gastrin is produced by G cells and is a potent stimulator of acid secretion.

Question 11

Which of the following statements about Secretin is FALSE?

Accepted Answer

It stimulates pepsin secretion — Secretin generally inhibits gastric functions; its primary role is pH regulation via bicarbonate, not pepsin stimulation.

Question 12

Which tissue layer provides for primary digestive motility?

Accepted Answer

Muscularis externa — The muscularis externa, consisting of circular and longitudinal layers, is responsible for peristalsis and segmentation.

Question 13

Which statement about bile is true?

Accepted Answer

Bile salts are essential for emulsification of fats — Bile salts emulsify fats, increasing the surface area for lipase action.

Question 14

Which statement regarding the swallowing reflex is FALSE?

Accepted Answer

The glottis is opened to allow food passage — During swallowing, the glottis is closed by the epiglottis to prevent aspiration into the airway.

Question 15

What is FALSE about tonic contractions in the GIT?

Accepted Answer

They occur only in the esophagus — Tonic contractions occur in many parts of the GIT, especially sphincters and the orad stomach, not just the esophagus.

Question 16

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

Accepted Answer

They are responsible for mixing chyme with digestive juices — Segmentation is a mixing movement that divides and recombines chyme without significant net forward movement.

Question 17

Secretion of saliva increases in all of the below EXCEPT:

Accepted Answer

Sympathetic dominance (Fright) — Sympathetic stimulation typically produces a small amount of thick, viscous saliva; high-stress (fright) leads to a dry mouth.

Question 18

The defecation reflex is characteristically:

Accepted Answer

Initiated by distension of the rectum — Rectal distension triggers the intrinsic and parasympathetic defecation reflexes.

Question 19

In the stomach, the chief (zymogenic) cells secrete:

Accepted Answer

Pepsinogen — Chief cells produce the inactive proenzyme pepsinogen.

Question 20

Intestinal secretions (Succus Entericus) contain which of the following?

Accepted Answer

Water, electrolytes, and mucus — Succus entericus is mainly water, electrolytes, and mucus providing a medium for absorption.

Question 21

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

Accepted Answer

Pernicious anemia — Loss of gastric glands (parietal cells) leads to loss of Intrinsic Factor, required for Vitamin B12 absorption, causing pernicious anemia.

Question 22

Which single statement below, about the stomach, is correct?

Accepted Answer

Receptive relaxation is mediated by the vagus nerve — Receptive relaxation allows the stomach to accommodate food and is a vagovagal reflex.

Question 23

Water transport in the intestine:

Accepted Answer

Occurs passively following the osmotic gradient created by solutes — Water follows solutes (like Na+ and glucose) osmotically; it is a passive process.

Question 24

Which statement about fat digestion and absorption is correct?

Accepted Answer

Micelles are necessary for transporting lipids to the brush border — Micelles render hydrophobic lipid digestion products soluble in the aqueous environment of the intestinal lumen.

Question 25

Which statement about protein digestion is most correct?

Accepted Answer

Peptides are broken down into amino acids by brush border enzymes — Final stages of protein digestion occur at the brush border and inside enterocytes via peptidases.

Question 26

Which statement about dietary fibre is most correct?

Accepted Answer

It provides bulk and can be fermented by colonic bacteria — Dietary fiber is indigestible by humans but is fermented by gut microbiota into short-chain fatty acids.

Question 27

Which statement about absorption is most correct?

Accepted Answer

Calcium absorption is enhanced by Vitamin D — Vitamin D (Calcitriol) stimulates the synthesis of calbindin, increasing calcium absorption.

Question 28

Which statement about the oral phase of digestion is INCORRECT?

Accepted Answer

The esophagus uses skeletal muscle throughout its entire length — The upper 1/3 is skeletal, middle 1/3 is mixed, and lower 1/3 is smooth muscle.

Question 29

Which statement about stomach lining cells is correct?

Accepted Answer

Enterochromaffin-like (ECL) cells secrete Histamine — ECL cells release histamine, which is a potent stimulator of acid secretion by parietal cells.

Question 30

Which statement about pancreatic enzyme secretion is correct?

Accepted Answer

Enterokinase activates trypsinogen to trypsin — Enterokinase (enteropeptidase) on the duodenal mucosa activates trypsinogen, which then activates other proteases.

Question 31

Which statement about post-meal motility is correct?

Accepted Answer

The gastrocolic reflex increases colonic motility after food enters the stomach — The gastrocolic reflex is a long reflex that stimulates mass movements in the colon following a meal.

Question 32

Which best describes colonic microbiota functions?

Accepted Answer

Synthesis of Vitamin K and B vitamins — Gut bacteria synthesize essential vitamins, particularly Vitamin K, which are absorbed in the colon.

Question 33

What explains fibre's protective effect against colon cancer?

Accepted Answer

By diluting potential carcinogens and reducing transit time — Fiber increases stool bulk and decreases transit time, limiting the exposure of the colonic mucosa to carcinogens.

Question 34

Which of the following is TRUE about the Intrinsic Factor?

Accepted Answer

It is essential for Vitamin B12 absorption in the ileum — Intrinsic factor binds B12; the complex is absorbed in the terminal ileum. Deficiency causes megaloblastic (pernicious) anemia.

Question 35

The presence of fat in the duodenum inhibits gastric emptying via:

Accepted Answer

The enterogastric reflex and CCK release — Both neural (enterogastric reflex) and hormonal (CCK) mechanisms inhibit gastric emptying when fat is detected.

Question 36

Slow waves (basal electrical rhythm) in the GIT:

Accepted Answer

Are caused by the interstitial cells of Cajal — Interstitial cells of Cajal act as pacemakers for the slow waves that determine the rhythm of contractions.

Question 37

The primary transmitter of the parasympathetic system to the GIT is:

Accepted Answer

Acetylcholine — Acetylcholine is the primary excitatory neurotransmitter for GIT motility and secretion.

Question 38

Which of the following describes the 'Law of the Gut' (Peristalsis)?

Accepted Answer

Contraction behind the bolus and relaxation in front of it — Peristalsis involves proximal contraction and distal relaxation to propel the bolus forward.

Question 39

The major site for the absorption of iron is the:

Accepted Answer

Duodenum and upper jejunum — Iron absorption occurs primarily in the proximal small intestine (duodenum).

Question 40

Which hormone is stimulated by the presence of fat and protein in the duodenum and causes gallbladder contraction?

Accepted Answer

CCK — CCK (Cholecystokinin) is the primary hormone for gallbladder contraction and pancreatic enzyme release.

Question 41

In the gastric phase of secretion, what is the main stimulus for gastrin release?

Accepted Answer

Distension of the stomach and presence of peptides/amino acids — Mechanical distension and chemical presence of breakdown products of protein directly stimulate G cells.

Question 42

The Migrating Motor Complex (MMC) is inhibited by:

Accepted Answer

Eating a meal — The MMC is a 'housekeeping' movement seen in the fasting state; it is abolished by the ingestion of food.

Question 43

Bicarbonate secretion into the duodenum comes from:

Accepted Answer

Brunner's glands and pancreatic duct cells — Brunner's glands (duodenum) and pancreatic ducts are the major sources of neutralizing bicarbonate.

Question 44

Which the following occurs during the Pharyngeal phase of swallowing?

Accepted Answer

The upper esophageal sphincter relaxes — During the pharyngeal phase, the UES opens to allow the bolus to enter the esophagus while respiration is inhibited.

Question 45

Which of the following inhibits gastrin release?

Accepted Answer

Antral pH below 2.0 — Low pH in the stomach triggers somatostatin release, which inhibits G cells via a negative feedback loop.

Question 46

The sodium-glucose linked transporter (SGLT-1) is responsible for:

Accepted Answer

Secondary active transport of glucose and galactose — SGLT-1 uses the sodium gradient to transport glucose and galactose into the enterocyte.

Question 47

Fatty acids are absorbed from the intestinal lumen into the enterocyte by:

Accepted Answer

Simple diffusion — Lipid digestion products in micelles diffuse passively across the lipid bilayer of the enterocyte membrane.

Question 48

What is the role of the 'Alkaline Tide'?

Accepted Answer

It represents bicarbonate release into the blood during acid secretion — When parietal cells secrete H+ into the stomach, they export HCO3- into the blood, temporarily increasing blood pH.

Question 49

The primary site for bile acid reabsorption is the:

Accepted Answer

Terminal ileum — Bile acids are recycled via the enterohepatic circulation, specifically via active transport in the terminal ileum.

Question 50

Which of the following is an example of an enterogastrone?

Accepted Answer

Secretin — Enterogastrones are hormones (like Secretin, CCK, GIP) released by the duodenum that inhibit gastric activity.

Weekly Year 2: GIT Physiology Exam - April 3, 2026 (Section

Questions, Answers & Explanations