Weekly Year 2: GIT Physiology Exam - April 21, 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, is responsible for peristalsis and segmentation.

Question 2

Which of the following statements about bile is TRUE?

Accepted Answer

Bile salts are essential for emulsification of lipids — Bile salts emulsify large fat globules into smaller droplets, increasing the surface area for lipase action.

Question 3

Regarding the swallowing (deglutition) reflex, which of the following is FALSE?

Accepted Answer

The glottis is opened to facilitate breathing during the swallow — During swallowing, the glottis is closed and the epiglottis covers the larynx to prevent aspiration.

Question 4

What is FALSE about tonic contractions in the GIT?

Accepted Answer

They occur primarily in the mid-esophagus — Tonic contractions occur in sphincters and the orad portion of the stomach; the mid-esophagus exhibits phasic contractions.

Question 5

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

Accepted Answer

They mix chyme with digestive secretions — Segmentation involve localized contractions that mix chyme and increase contact with the mucosa for absorption.

Question 6

Secretion of saliva increases in all of the following EXCEPT:

Accepted Answer

Sleep — Salivary secretion decreases significantly during sleep, leading to a dry mouth.

Question 7

The defecation reflex is integrated primarily in the:

Accepted Answer

Sacral spinal cord — The parasympathetic defecation reflex is integrated in the sacral segments of the spinal cord (S2-S4).

Question 8

Intestinal secretions (Succus entericus) primarily contain:

Accepted Answer

Water, electrolytes, and mucus — Succus entericus is mainly water, mucus, and electrolytes; most digestive enzymes are brush-border bound.

Question 9

A 55-year-old man with chronic gastric gland destruction is most likely to develop:

Accepted Answer

Pernicious anemia — Destruction of gastric glands (parietal cells) leads to loss of intrinsic factor, required for Vitamin B12 absorption.

Question 10

Vasoactive Intestinal Peptide (VIP) causes:

Accepted Answer

Relaxation of gastrointestinal sphincters — VIP is an inhibitory neurotransmitter that relaxes smooth muscle and sphincters.

Question 11

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

Accepted Answer

Acidic chyme (pH < 4.5) in the duodenum — S-cells in the duodenum release secretin in response to low pH; secretin then stimulates bicarbonate secretion.

Question 12

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 slows down movement.

Question 13

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

Accepted Answer

Gastrointestinal secretion and local blood flow — The submucosal plexus is primarily involved in controlling secretion and local blood flow.

Question 14

Cholecystokinin (CCK) has which of the following effects?

Accepted Answer

Stimulates contraction of the gallbladder — CCK causes gallbladder contraction and relaxation of the sphincter of Oddi to release bile into the duodenum.

Question 15

Which statement regarding Gastrin is TRUE?

Accepted Answer

It is stimulated by distension of the stomach — Gastrin is released by G-cells in the antrum in response to protein products, distension, and vagal stimulation.

Question 16

Which of the following describes the Migrating Motor Complex (MMC)?

Accepted Answer

It cleans the small intestine of residual food during fasting — The MMC is house-keeping motility that sweeps the gut during the inter-digestive (fasting) state.

Question 17

What is the primary stimulus for the gastrocolic reflex?

Accepted Answer

Distension of the stomach — Food in the stomach (distension) triggers increased motility in the colon, often leading to defecation.

Question 18

Which pancreatic enzyme is responsible for activating other proteolytic enzymes?

Accepted Answer

Trypsin — Once trypsinogen is converted to trypsin by enterokinase, trypsin autocatalytically activates more trypsin and other proteases.

Question 19

Which of the following is NOT a component of the gastric barrier?

Accepted Answer

Release of gastrin into the lumen — Gastrin is a hormone released into the blood, not the lumen, and is not a physical barrier component.

Question 20

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

Accepted Answer

Terminal ileum — Bile salts are reabsorbed via active transport in the terminal ileum as part of the enterohepatic circulation.

Question 21

Which statement about fat digestion and absorption is CORRECT?

Accepted Answer

Micelles deliver lipids to the mucosal surface — Micelles are water-soluble carriers that bring lipid products to the brush border for passive absorption.

Question 22

Secondary active transport of glucose in the small intestine involves:

Accepted Answer

Sodium-glucose co-transporter (SGLT1) — Glucose and galactose are absorbed via SGLT1, which utilizes the sodium gradient created by the Na-K ATPase.

Question 23

Which of the following inhibits gastric acid secretion?

Accepted Answer

Somatostatin — Somatostatin is the 'universal inhibitor' in the GIT and directly inhibits parietal cell acid secretion.

Question 24

The 'Law of the Gut' refers to:

Accepted Answer

The direction of peristalsis (analward) — The Law of the Gut describes the distension-induced contraction above a bolus and relaxation below it, moving contents analward.

Question 25

The cephalic phase of gastric secretion is mediated by:

Accepted Answer

The Vagus nerve — The cephalic phase occurs before food reaches the stomach and is mediated via vagal stimulation.

Question 26

Which cell type in the stomach secretes pepsinogen?

Accepted Answer

Chief cells — Chief (peptic) cells secrete pepsinogen, which is activated to pepsin in an acidic environment.

Question 27

Which of the following would DECREASE the rate of gastric emptying?

Accepted Answer

Presence of fat in the duodenum — Fat in the duodenum triggers CCK and the enterogastric reflex, which slow down gastric emptying.

Question 28

In the intestine, water transport is primarily:

Accepted Answer

Passive, following the osmotic gradient — Water absorption is always passive and follows the movement of solutes like sodium and nutrients.

Question 29

The primary function of the colon is:

Accepted Answer

Absorption of water and electrolytes — The colon primarily absorbs water and electrolytes from the remaining chyme, forming semi-solid feces.

Question 30

Which statement about dietary fiber is CORRECT?

Accepted Answer

It adds bulk to the stool and promotes regular bowel movements — Fiber is resistant to human enzymes and provides bulk which stimulates peristalsis.

Question 31

What is the role of the 'Alkaline Tide' after a meal?

Accepted Answer

It is caused by the release of bicarbonate into the blood in exchange for Cl — During HCl production, bicarbonate is transported out of the parietal cell into the blood, temporarily raising venous pH.

Question 32

The main component of the 'Slow Waves' in the GIT is:

Accepted Answer

Fluctuations in resting membrane potential — Slow waves (basal electrical rhythm) are spontaneous oscillations in membrane potential generated by Interstitial Cells of Cajal.

Question 33

Which vitamin requires a specific protein from the stomach for its absorption?

Accepted Answer

Vitamin B12 — Vitamin B12 requires Intrinsic Factor (IF) secreted by gastric parietal cells for absorption in the ileum.

Question 34

Which hormone is responsible for 'cleaning' the gut during the interdigestive period?

Accepted Answer

Motilin — Motilin levels rise during fasting and are responsible for initiating the Migrating Motor Complex.

Question 35

The absorption of iron:

Accepted Answer

Is enhanced by Vitamin C — Vitamin C (ascorbic acid) keeps iron in the ferrous (Fe2+) state, which is more easily absorbed.

Question 36

The gastric 'Receptive Relaxation' is mediated by:

Accepted Answer

Vagovagal reflex — Distension of the esophagus or stomach triggers a vagovagal reflex that relaxes the gastric fundus to accommodate food.

Question 37

What is the effect of sympathetic stimulation on the GIT?

Accepted Answer

Decreased secretion and blood flow — Sympathetic stimulation typically inhibits GIT activity and causes vasoconstriction of the splanchnic vessels.

Question 38

Which electrolyte is actively secreted into the lumen in exchange for HCO3- in the colon?

Accepted Answer

Chloride — The colon absorbs Chloride in exchange for bicarbonate secretion.

Question 39

Fatty acids are re-esterified into triglycerides within the intestinal cells and packaged into:

Accepted Answer

Chylomicrons — After absorption, fats are rebuilt into triglycerides and exit the cell in chylomicrons via exocytosis.

Question 40

The primary stimulus for the release of CCK is:

Accepted Answer

Peptones and long-chain fatty acids in the duodenum — CCK is released from I-cells primarily when fat and protein products enter the small intestine.

Question 41

Enterokinase (enteropeptidase) is found in the:

Accepted Answer

Brush border of the small intestine — Enterokinase is a brush border enzyme that activates trypsinogen to trypsin.

Question 42

Which of the following describes the function of the haustrations in the colon?

Accepted Answer

Mixing and providing time for water absorption — Haustrations are slow, mixing movements in the colon that facilitate water and electrolyte absorption.

Question 43

The presence of food in the stomach increases the frequency of mass movements in the colon via the:

Accepted Answer

Gastrocolic reflex — The gastrocolic reflex increases colonic motility in response to stomach stretching.

Question 44

What happens to the majority of secreted bile salts?

Accepted Answer

They are reabsorbed in the terminal ileum — About 95% of bile salts are recycled back to the liver through the portal vein (enterohepatic circulation).

Question 45

Which hormone stimulates the secretion of pancreatic enzymes?

Accepted Answer

CCK — CCK is the primary stimulant for the acinar cells of the pancreas to secrete digestive enzymes.

Question 46

Which statement about the intestinal mucosa is TRUE?

Accepted Answer

Villi increase the surface area for absorption — The presence of plicae circulares, villi, and microvilli enormously increases the surface area for nutrient absorption.

Question 47

Amylase is produced by which of the following?

Accepted Answer

Salivary glands and Pancreas — Both the salivary glands (ptyalin) and the pancreas secrete amylase for carbohydrate digestion.

Question 48

Failure of the lower esophageal sphincter to relax during swallowing is called:

Accepted Answer

Achalasia — Achalasia is a motility disorder where the LES fails to relax and peristalsis is impaired.

Question 49

Gastric Inhibitory Peptide (GIP) primarily:

Accepted Answer

Stimulates insulin release — GIP is now often called Glucose-dependent Insulinotropic Peptide because its main physiological role is stimulating insulin.

Question 50

Which of the following is an example of an enterogastrone?

Accepted Answer

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

Weekly Year 2: GIT Physiology Exam - April 21, 2026 (Section

Questions, Answers & Explanations