Weekly Year 2: GIT Physiology Exam - May 29, 2026 (Section A

Question 1

Which of the following statements about the myenteric (Auerbach's) plexus is FALSE?

Accepted Answer

It is responsible for regulating exocrine gland secretion. — The myenteric plexus primarily controls motility (muscle contraction and relaxation) of the gastrointestinal tract. Regulation of exocrine gland secretion is primarily controlled by the submucosal (Meissner's) plexus.

Question 2

Which tissue layer provides for primary digestive motility?

Accepted Answer

Muscularis externa — The muscularis externa, composed of inner circular and outer longitudinal smooth muscle layers, is responsible for the propulsive and mixing movements of the gastrointestinal tract.

Question 3

Which statement about bile is TRUE?

Accepted Answer

Bile salts aid in the emulsification of fats. — Bile salts are amphipathic molecules that emulsify fats, increasing their surface area for enzyme action. Bile is produced by the liver and stored in the gallbladder, which releases it in response to CCK. While bile is alkaline, its primary role isn't to neutralize stomach acid to the extent that pancreatic bicarbonate does.

Question 4

Which statement regarding the swallowing reflex (deglutition) is FALSE?

Accepted Answer

Food is propelled down the esophagus by peristalsis. — While peristalsis is crucial for esophageal transport, the initial propulsion of the bolus through the pharynx is a reflex action involving coordinated muscle contractions. Peristalsis is the wave-like muscle contraction that moves food down the esophagus.

Question 5

Which of the following statements about the absorptive cells of the small intestine (enterocytes) is TRUE?

Accepted Answer

They possess microvilli to increase surface area for absorption. — Enterocytes are characterized by their apical brush border, which consists of microvilli that significantly increase the surface area for nutrient absorption. Their primary role is absorption, not secretion of digestive enzymes, which are produced by other cells in the intestinal glands.

Question 6

What is FALSE about tonic contractions in the gastrointestinal tract?

Accepted Answer

They are characterized by rapid, rhythmic contractions. — Tonic contractions are sustained and occur at a low level, important for maintaining tone in sphincters and preventing reflux. Rapid, rhythmic contractions are characteristic of phasic contractions.

Question 7

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

Accepted Answer

They are circular contractions that mix chyme with digestive juices. — Segmenting movements are localized contractions of the circular muscle that churn and mix the chyme with digestive secretions, facilitating digestion and absorption. They do not primarily propel chyme aborally; that's the role of peristalsis.

Question 8

Secretion of saliva increases in all of the below except:

Accepted Answer

Sympathetic stimulation — While chewing and thinking about food stimulate salivary secretion, sympathetic stimulation generally leads to a thick, viscous saliva with less volume. Ingestion of dry food would also typically trigger an increase in saliva to aid lubrication and swallowing.

Question 9

Defecation is a reflex action regulated by:

Accepted Answer

Both somatic and autonomic nervous systems — Defecation involves both voluntary (somatic control of external anal sphincter) and involuntary (autonomic control of internal anal sphincter and rectal smooth muscle) components. The primary reflex pathways are mediated by the autonomic nervous system.

Question 10

In the stomach, which of the following is TRUE?

Accepted Answer

G cells secrete gastrin. — Chief cells secrete pepsinogen, parietal cells secrete HCl and intrinsic factor, and G cells secrete gastrin. The pyloric sphincter relaxes in response to signals that prepare the duodenum for incoming chyme.

Question 11

Intestinal secretions contain:

Accepted Answer

Mucus and electrolytes — Intestinal glands secrete mucus for lubrication and protection, along with water and electrolytes like sodium, potassium, and chloride, which contribute to the fluid environment for digestion and absorption. Bile is secreted by the liver and gallbladder, and pancreatic enzymes are secreted by the pancreas.

Question 12

A 55-year-old man with chronic alcohol consumption presents with nonspecific complaints of dyspepsia. Examination reveals destruction of gastric glands. This predisposes him to

Accepted Answer

Pernicious anemia — Chronic alcohol consumption can damage gastric glands, particularly the parietal cells. Parietal cells are responsible for secreting hydrochloric acid (HCl) and intrinsic factor. Destruction of parietal cells leads to hypochlorhydria (decreased gastric acid) and impaired absorption of vitamin B12 due to lack of intrinsic factor, leading to pernicious anemia.

Question 13

Which of the following statements about Gastrin is TRUE?

Accepted Answer

It stimulates the secretion of pepsinogen and HCl. — Gastrin is secreted by G cells in the stomach and duodenum. Its release is stimulated by distension of the stomach, presence of peptides, and a rise in stomach pH. It stimulates the secretion of pepsinogen and HCl and increases gastric motility.

Question 14

Which of the following statements about VIP (Vasoactive Intestinal Peptide) is TRUE?

Accepted Answer

It causes vasodilation and increases intestinal blood flow. — VIP is a peptide hormone that has several effects, including inhibition of gastric acid secretion, stimulation of pancreatic and intestinal secretion, and vasodilation. It also inhibits intestinal motility and promotes water and electrolyte secretion.

Question 15

Stimulation of gastrointestinal secretion can be caused by all of the following except:

Accepted Answer

Sympathetic stimulation — Sympathetic stimulation generally inhibits gastrointestinal secretions, while the presence of food, vagal stimulation (parasympathetic), and hormonal signals promote secretion.

Question 16

The Secretin hormone:

Accepted Answer

Stimulates the secretion of bicarbonate-rich fluid from the pancreas and bile ducts. — Secretin is released by the duodenum in response to acidic chyme. Its primary action is to stimulate the pancreas and bile ducts to secrete bicarbonate-rich fluid, which neutralizes stomach acid. It inhibits gastric acid secretion and stimulates pancreatic enzyme secretion.

Question 17

Inhibition of the myenteric plexus leads to which of the following?

Accepted Answer

Decreased intestinal motility — The myenteric plexus is crucial for coordinating peristalsis. Inhibition of this plexus would lead to a significant decrease in intestinal motility, potentially causing constipation and reduced mixing of luminal contents.

Question 18

Stimulation of the submucosal plexus results in an increase in which of the following?

Accepted Answer

Secretion of intestinal juices — The submucosal plexus (Meissner's plexus) primarily controls glandular secretions and local blood flow within the intestinal wall. While it influences local muscle activity, the primary control of peristalsis and major muscle contractions lies with the myenteric plexus. Stimulation of the submucosal plexus leads to increased secretion of intestinal juices.

Question 19

Regarding the GIT hormones affecting gastric function, which statement is TRUE?

Accepted Answer

Secretin stimulates gastric acid secretion. — Secretin is released in response to acid and inhibits gastric acid secretion. Gastrin is stimulated by increased gastric pH. CCK slows gastric emptying. GIP (Gastric Inhibitory Peptide) is involved in regulating gastric secretion and motility, not primarily protein digestion.

Question 20

Cholecystokinin (CCK) is primarily released in response to:

Accepted Answer

Fatty acids and amino acids in the duodenum — CCK is released from I cells in the duodenum and jejunum primarily in response to the presence of fats and proteins (amino acids) in the lumen. It stimulates gallbladder contraction, pancreatic enzyme secretion, and inhibits gastric emptying.

Question 21

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

Accepted Answer

The presence of acidic chyme in the duodenum — Secretin is released by the S cells of the duodenum and jejunum in response to a drop in pH, meaning the presence of acidic chyme entering from the stomach. Its main role is to neutralize this acid.

Question 22

It is known that Gastrin:

Accepted Answer

Is stimulated by high gastric pH. — Gastrin is produced by G cells, mainly in the antrum of the stomach. It is stimulated by the presence of peptides, distension, and a rise in gastric pH. It stimulates HCl and pepsinogen secretion and increases gastric motility.

Question 23

It is known that Secretin:

Accepted Answer

Stimulates the secretion of bicarbonate from the pancreas. — Secretin's primary action is to stimulate the secretion of bicarbonate-rich fluid from the pancreas and bile ducts, thereby neutralizing the acidic chyme. It is released in response to acid, not fats. It inhibits gastric acid secretion.

Question 24

Concerning the Gastrin hormone, which of the following statements is TRUE?

Accepted Answer

It promotes the secretion of pepsinogen. — Gastrin stimulates the secretion of pepsinogen from chief cells. Its secretion is inhibited by high acidity and stimulated by alkaline conditions and the presence of peptides. While some gastrin is produced in the duodenum, the majority is from the stomach. It also stimulates gastric emptying.

Question 25

Which of the following statements about the submucosal (Meissner's) plexus is FALSE?

Accepted Answer

It receives direct input from sympathetic and parasympathetic nerves. — The submucosal plexus receives indirect input from the sympathetic and parasympathetic nervous systems via connections with the myenteric plexus. While it regulates secretions and local blood flow, direct innervation from the CNS is more complex.

Question 26

Which of the following is characteristic of the pharyngeal phase of swallowing?

Accepted Answer

The soft palate elevates to close off the nasopharynx. — During the pharyngeal phase, the soft palate elevates to prevent food from entering the nasal cavity. The tongue pushes the bolus backward, the upper esophageal sphincter relaxes, and the epiglottis covers the airway.

Question 27

Which statement about the stomach lining cells is correct?

Accepted Answer

Mucous neck cells secrete pepsinogen. — Mucous neck cells secrete mucus. Parietal cells secrete HCl and intrinsic factor. Chief cells secrete pepsinogen. Enteroendocrine cells secrete hormones like gastrin.

Question 28

Which statement about pancreatic enzyme secretion is correct?

Accepted Answer

Secretin stimulates the secretion of pancreatic enzymes. — Pancreatic lipase is secreted in its active form. Secretin stimulates bicarbonate secretion, while CCK stimulates enzyme secretion. Pancreatic amylase digests carbohydrates, not proteins.

Question 29

Which statement about post-meal motility is correct?

Accepted Answer

The small intestine exhibits increased peristalsis to propel chyme. — Post-meal motility in the small intestine is dominated by peristaltic contractions that move chyme toward the large intestine. The migrating motor complex occurs during the interdigestive period. High-fat meals slow gastric emptying. The ileocecal valve typically opens to allow chyme into the colon.

Question 30

Which best describes colonic microbiota functions?

Accepted Answer

Synthesis of vitamin K and short-chain fatty acids. — Colonic microbiota are essential for synthesizing vitamin K and other B vitamins, and for fermenting undigested carbohydrates to produce short-chain fatty acids, which are an energy source for colonocytes. The colon's primary role is water and electrolyte absorption, not nutrient absorption or enzyme secretion.

Question 31

What explains fibre's protective effect against colon cancer?

Accepted Answer

Increased fecal bulk diluting carcinogens. — Dietary fiber increases fecal bulk and speeds up transit time, which dilutes potential carcinogens and reduces their contact time with the colonic mucosa. It also promotes beneficial bacterial fermentation.

Question 32

Which statement about fat digestion and absorption is correct?

Accepted Answer

Bile salts are essential for the absorption of fat-soluble vitamins. — Bile salts not only emulsify fats but are also crucial for the absorption of fat-soluble vitamins (A, D, E, K). While some fat digestion starts in the stomach with lingual lipase, it's minimal. Triglycerides are reassembled into chylomicrons within enterocytes and enter the lymphatic system.

Question 33

Which statement about protein digestion is most correct?

Accepted Answer

Trypsinogen is activated by enterokinase. — Trypsinogen, a zymogen secreted by the pancreas, is activated by the enzyme enterokinase (or enteropeptidase) secreted by the duodenal brush border. Protein digestion begins in the stomach with pepsin. Pepsin is secreted by chief cells, not parietal cells. Amino acids are absorbed by both active transport and facilitated diffusion.

Question 34

Which statement about dietary fibre is most correct?

Accepted Answer

It can bind to bile acids, potentially lowering cholesterol levels. — Dietary fiber is not digested by human enzymes but is fermented by colonic bacteria. Soluble fibers can bind to bile acids, which are then excreted, leading to increased bile acid synthesis from cholesterol, thus lowering blood cholesterol. It is not a source of readily available glucose.

Question 35

Which statement about absorption is most correct?

Accepted Answer

Fatty acids are absorbed into the portal vein. — Glucose absorption in the small intestine relies on sodium-glucose cotransporters (SGLT1) on the apical membrane (secondary active transport) and glucose transporters (GLUT2) on the basolateral membrane (facilitated diffusion). Water absorption is primarily passive via osmosis. Most absorbed fats enter the lymphatics. Vitamins are absorbed in both the small and large intestines.

Weekly Year 2: GIT Physiology Exam - May 29, 2026 (Section A

Questions, Answers & Explanations