Weekly Year 2: GIT Physiology Exam - March 13, 2026 (Section

Question 1

Regarding GIT hormones, which of the following is correct?

Accepted Answer

Cholecystokinin (CCK) stimulates gallbladder contraction — CCK is released from the duodenum in response to fat and protein and causes gallbladder contraction to release bile.

Question 2

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

Accepted Answer

Stimulation of water and electrolyte secretion — VIP is an inhibitory neurotransmitter that relaxes smooth muscle but stimulates intestinal secretion of water and electrolytes.

Question 3

Stimulation of gastrointestinal secretion involves:

Accepted Answer

The Enteric Nervous System and Parasympathetic input — The ENS (Mesissner's plexus) and the Vagus nerve (Parasympathetic) are the primary stimulators of GIT secretion.

Question 4

The hormone secretin is characterized by:

Accepted Answer

Stimulating the release of bicarbonate-rich pancreatic juice — Secretin is known as 'nature's antacid' because it stimulates bicarbonate secretion from the pancreatic ducts.

Question 5

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

Accepted Answer

Decreased gastrointestinal motility — The myenteric plexus primary controls the motor activity/motility of the GIT.

Question 6

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

Accepted Answer

Secretory activity and local blood flow — The submucosal plexus is primarily responsible for controlling secretion and local blood flow.

Question 7

Which hormone inhibits gastric emptying and gastric acid secretion?

Accepted Answer

Enterogastrone (like GIP or CCK) — Hormones like GIP, CCK, and Secretin act as 'enterogastrones' to slow gastric activity when chyme enters the duodenum.

Question 8

Cholecystokinin (CCK) secretion is most strongly stimulated by:

Accepted Answer

Amino acids and fatty acids in the small intestine — The presence of fat and protein breakdown products in the duodenum is the most potent trigger for CCK release.

Question 9

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

Accepted Answer

HCl (low pH) in the duodenum — Secretin is released when the pH of the duodenal contents falls below 4.5.

Question 10

It is known that Gastrin:

Accepted Answer

Increases gastric acid secretion by parietal cells — Gastrin stimulates parietal cells to secrete HCl and also has a trophic effect on the gastric mucosa.

Question 11

Which statement about the hormone Secretin is correct?

Accepted Answer

It inhibits gastric acid secretion — Secretin acts to neutralize acid by stimulating bicarbonate and inhibiting further acid production in the stomach.

Question 12

Concerning the Gastrin hormone:

Accepted Answer

Its secretion is inhibited by a low luminal pH (< 2.0) — Gastrin secretion is regulated by a feedback loop where low pH inhibits its further release.

Question 13

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

Accepted Answer

Parietal cells secrete HCl and intrinsic factor — Parietal (oxyntic) cells are responsible for both hydrochloric acid and intrinsic factor (necessary for Vitamin B12 absorption).

Question 14

Water transport in the intestine:

Accepted Answer

Follows the osmotic gradient created by solute absorption — Water movement in the gut is passive and follows the osmotic gradient created by the transport of ions and nutrients.

Question 15

Which statement about fat digestion and absorption is correct?

Accepted Answer

Micelles help ferry lipids to the brush border — Micelles are essential for keeping lipid breakdown products in solution and moving them to the enterocyte surface.

Question 16

Which statement about protein digestion is most correct?

Accepted Answer

Final digestion to amino acids occurs mainly at the brush border or intracellularly — While pancreatic enzymes break proteins into oligopeptides, brush border peptidases and intracellular peptidases complete the process.

Question 17

Which statement about dietary fiber is most correct?

Accepted Answer

It is fermented by colonic bacteria to produce short-chain fatty acids — Colonic bacteria ferment fiber into SCFAs (like butyrate), which are used as energy by colonocytes.

Question 18

Which statement about absorption is most correct?

Accepted Answer

Vitamin B12 absorption requires intrinsic factor and occurs in the terminal ileum — Vitamin B12 binds to IF in the stomach/duodenum and is absorbed via specific receptors in the terminal ileum.

Question 19

Which statement about the oral phase of digestion is INCORRECT?

Accepted Answer

The oral phase is entirely under hormonal control — The oral phase (salivation and chewing) is primarily under neural (autonomic) control, not hormonal.

Question 20

Which statement about stomach lining cells is correct?

Accepted Answer

Chief cells secrete pepsinogen — Chief (peptic) cells secrete the proenzyme pepsinogen; G cells are in the antrum; D cells secrete somatostatin.

Question 21

Which statement about pancreatic enzyme secretion is correct?

Accepted Answer

Enterokinase activates trypsinogen to trypsin — Enterokinase (enteropeptidase), located on the duodenal brush border, is the trigger that activates trypsinogen.

Question 22

Which statement about post-meal motility is correct?

Accepted Answer

Segmentation is the primary movement in the small intestine during digestion — Segmentation is the mixing movement predominant during the digestive phase; the MMC occurs during the fasting state.

Question 23

Which best describes colonic microbiota functions?

Accepted Answer

Synthesis of Vitamin K and certain B vitamins — The gut microbiome is crucial for the synthesis of Vitamin K and some B vitamins (e.g., Biotin).

Question 24

What explains fiber's protective effect against colon cancer?

Accepted Answer

It dilutes potential carcinogens and speeds up transit time — By increasing bulk and decreasing transit time, fiber reduces the exposure of the colon wall to toxins/carcinogens.

Question 25

Which of the following statements is FALSE?

Accepted Answer

The large intestine secretes significant amounts of digestive enzymes — The large intestine secretes mucus but does not produce digestive enzymes; digestion there is performed by bacteria.

Question 26

Which tissue layer provides for primary digestive motility?

Accepted Answer

Muscularis externa — The muscularis externa (containing circular and longitudinal muscles) is responsible for peristalsis and segmentation.

Question 27

Which statement about bile is true?

Accepted Answer

Bile salts are recirculated via the enterohepatic circulation — 95% of bile salts are reabsorbed in the terminal ileum and returned to the liver.

Question 28

Which statement regarding the swallowing reflex is false?

Accepted Answer

It is entirely voluntary from start to finish — Only the first stage of swallowing (oral) is voluntary; the pharyngeal and esophageal stages are involuntary reflexes.

Question 29

Which of the following statements is TRUE?

Accepted Answer

Gastric inhibitory peptide (GIP) stimulates insulin release — GIP (Glucose-dependent Insulinotropic Peptide) stimulates insulin secretion in response to glucose in the gut.

Question 30

What is false about tonic contractions?

Accepted Answer

They are characteristic of the small intestine during active mixing — Tonic contractions are sustained; the mixing movements in the small intestine are 'phasic' (rhythmical) contractions.

Question 31

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

Accepted Answer

They mix chyme with digestive juices and increase contact with mucosa — Segmentation involves localized contractions of circular muscle to mix contents and facilitate absorption.

Question 32

Secretion of saliva increases in all of the below EXCEPT:

Accepted Answer

Sympathetic dominance (stress) — Sympathetic stimulation typically produces a small volume of thick, viscous saliva; high-stress 'fight or flight' often causes dry mouth.

Question 33

The presence of acid in the duodenum inhibits gastric secretion via:

Accepted Answer

The enterogastric reflex — The enterogastric reflex (neural) and enterogastrones (hormonal) inhibit gastric activity when the duodenum is acidic or full.

Question 34

Which of the following is the primary site of iron absorption?

Accepted Answer

Duodenum and upper jejunum — Iron is predominantly absorbed in the proximal small intestine (duodenum).

Question 35

The defecation reflex is primarily integrated in the:

Accepted Answer

Sacral spinal cord — The parasympathetic defecation reflex is mediated through the pelvic nerves in the sacral segments of the spinal cord.

Question 36

Which enzyme is responsible for the digestion of polysaccharides into disaccharides?

Accepted Answer

Amylase — Amylase (salivary and pancreatic) breaks down starch (polysaccharide) into smaller sugars like maltose (disaccharide).

Question 37

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

Accepted Answer

Vagovagal reflex — Receptive relaxation allows the stomach to accommodate food; it is a vagovagal reflex involving VIP as a neurotransmitter.

Question 38

Which vitamin absorption is impaired in a patient with a total gastrectomy?

Accepted Answer

Vitamin B12 — Gastrectomy removes parietal cells, leading to a lack of Intrinsic Factor, which is essential for B12 absorption.

Question 39

Secondary active transport of glucose into the enterocyte is coupled with:

Accepted Answer

Sodium — Glucose enters the cell via SGLT-1, which utilizes the sodium gradient maintained by the Na/K ATPase.

Question 40

The alkaline tide refers to:

Accepted Answer

The rise in blood pH after a meal due to HCl secretion into the stomach — When parietal cells secrete H+ into the stomach, they secrete HCO3- into the blood, temporarily raising the systemic pH.

Question 41

Which peptide is produced by the G-cells in the antrum of the stomach?

Accepted Answer

Gastrin — Gastrin is the primary hormone produced by G-cells.

Question 42

The effect of Acetylcholine on the GIT is generally:

Accepted Answer

Excitatory to motility and secretion — ACh is the primary neurotransmitter of the parasympathetic system and the excitatory neurons of the ENS.

Question 43

Which of the following is a function of the liver?

Accepted Answer

Synthesis of plasma proteins and bile acids — The liver synthesizes albumin, clotting factors, and bile acids.

Question 44

What is the primary stimulus for the intestinal phase of gastric secretion?

Accepted Answer

Presence of amino acids/peptides in the duodenum — The intestinal phase accounts for a small amount of gastric secretion, triggered largely by peptides in the duodenum.

Question 45

The primary component of the Migrating Motor Complex (MMC) is:

Accepted Answer

The hormone Motilin — Motilin levels cycle during fasting and trigger the MMC waves.

Question 46

Bicarbonate secretion by the pancreas is primarily regulated by:

Accepted Answer

Secretin — Secretin specifically targets the pancreatic duct cells to release water and bicarbonate.

Question 47

Fatty acids are absorbed from the lumen into the enterocyte via:

Accepted Answer

Simple diffusion — Once micelles release fatty acids at the brush border, they cross the lipid membrane via simple diffusion.

Question 48

Which of the following describes the gastrocolic reflex?

Accepted Answer

Distension of the stomach increases motility of the colon — The gastrocolic reflex is the increase in colonic mass movements following the entry of food into the stomach.

Question 49

Which enzyme is NOT a proteolytic enzyme secreted by the pancreas?

Accepted Answer

Pepsin — Pepsin is a gastric protease, not a pancreatic one.

Question 50

The primary role of the Brunner's glands is to:

Accepted Answer

Secrete alkaline mucus in the duodenum — Brunner's glands (in the duodenum) secrete bicarbonate-rich mucus to protect the mucosa from acidic chyme.

Weekly Year 2: GIT Physiology Exam - March 13, 2026 (Section

Questions, Answers & Explanations