,BIOL331/BIOL 331 Module 7
Pathophysiology | Portage |Q&A| 26/27
Actual (PDF)
1. A physiologist is studying the structural organization of the gastrointestinal tract. Which layer of the
GI wall is responsible for peristalsis and segmentation?
A) Mucosa
B) Submucosa
C) Muscularis externa
D) Serosa
Correct Answer: Muscularis externa
Rationale: The muscularis externa contains the circular and longitudinal smooth muscle layers that
generate peristalsis and segmentation. The mucosa is the innermost lining for absorption and
secretion, the submucosa contains blood vessels and the submucosal plexus, and the serosa is the
outer covering, making them incorrect.
2. A researcher is examining the enteric nervous system and its role in controlling GI motility. Which
plexus is located between the circular and longitudinal muscle layers and primarily controls motility?
A) Submucosal plexus
B) Myenteric plexus
C) Celiac plexus
,D) Hypogastric plexus
Correct Answer: Myenteric plexus
Rationale: The myenteric plexus (Auerbach's plexus) lies between the circular and longitudinal muscle
layers and primarily controls GI motility. The submucosal plexus (Meissner's plexus) controls
secretions and absorption, while the celiac and hypogastric plexuses are autonomic ganglia outside
the GI wall.
3. A student is examining the hormone that stimulates gastric acid secretion by parietal cells. Which
hormone performs this function?
A) Secretin
B) Gastrin
C) Cholecystokinin
D) Ghrelin
Correct Answer: Gastrin
Rationale: Gastrin is secreted by G cells in the stomach antrum and stimulates parietal cells to secrete
hydrochloric acid. Secretin stimulates bicarbonate secretion from the pancreas, cholecystokinin
stimulates gallbladder contraction and pancreatic enzyme secretion, and ghrelin stimulates food
intake.
4. A researcher is studying the hormone that stimulates the pancreas to release bicarbonate to
neutralize chyme. Which hormone is being examined?
A) Gastrin
, B) Secretin
C) Cholecystokinin
D) Motilin
Correct Answer: Secretin
Rationale: Secretin is released by the duodenum in response to acidic chyme and stimulates the
pancreas to secrete bicarbonate. Gastrin stimulates acid secretion, cholecystokinin stimulates enzyme
secretion and gallbladder contraction, and motilin regulates the migrating motor complex.
5. A physiologist is studying the hormone that stimulates gallbladder contraction and pancreatic
enzyme secretion. Which hormone performs these functions?
A) Secretin
B) Gastrin
C) Cholecystokinin
D) Ghrelin
Correct Answer: Cholecystokinin
Rationale: Cholecystokinin is released by the duodenum in response to fats and proteins and
stimulates gallbladder contraction and pancreatic enzyme secretion. Secretin stimulates bicarbonate
secretion, gastrin stimulates acid secretion, and ghrelin stimulates appetite.
Pathophysiology | Portage |Q&A| 26/27
Actual (PDF)
1. A physiologist is studying the structural organization of the gastrointestinal tract. Which layer of the
GI wall is responsible for peristalsis and segmentation?
A) Mucosa
B) Submucosa
C) Muscularis externa
D) Serosa
Correct Answer: Muscularis externa
Rationale: The muscularis externa contains the circular and longitudinal smooth muscle layers that
generate peristalsis and segmentation. The mucosa is the innermost lining for absorption and
secretion, the submucosa contains blood vessels and the submucosal plexus, and the serosa is the
outer covering, making them incorrect.
2. A researcher is examining the enteric nervous system and its role in controlling GI motility. Which
plexus is located between the circular and longitudinal muscle layers and primarily controls motility?
A) Submucosal plexus
B) Myenteric plexus
C) Celiac plexus
,D) Hypogastric plexus
Correct Answer: Myenteric plexus
Rationale: The myenteric plexus (Auerbach's plexus) lies between the circular and longitudinal muscle
layers and primarily controls GI motility. The submucosal plexus (Meissner's plexus) controls
secretions and absorption, while the celiac and hypogastric plexuses are autonomic ganglia outside
the GI wall.
3. A student is examining the hormone that stimulates gastric acid secretion by parietal cells. Which
hormone performs this function?
A) Secretin
B) Gastrin
C) Cholecystokinin
D) Ghrelin
Correct Answer: Gastrin
Rationale: Gastrin is secreted by G cells in the stomach antrum and stimulates parietal cells to secrete
hydrochloric acid. Secretin stimulates bicarbonate secretion from the pancreas, cholecystokinin
stimulates gallbladder contraction and pancreatic enzyme secretion, and ghrelin stimulates food
intake.
4. A researcher is studying the hormone that stimulates the pancreas to release bicarbonate to
neutralize chyme. Which hormone is being examined?
A) Gastrin
, B) Secretin
C) Cholecystokinin
D) Motilin
Correct Answer: Secretin
Rationale: Secretin is released by the duodenum in response to acidic chyme and stimulates the
pancreas to secrete bicarbonate. Gastrin stimulates acid secretion, cholecystokinin stimulates enzyme
secretion and gallbladder contraction, and motilin regulates the migrating motor complex.
5. A physiologist is studying the hormone that stimulates gallbladder contraction and pancreatic
enzyme secretion. Which hormone performs these functions?
A) Secretin
B) Gastrin
C) Cholecystokinin
D) Ghrelin
Correct Answer: Cholecystokinin
Rationale: Cholecystokinin is released by the duodenum in response to fats and proteins and
stimulates gallbladder contraction and pancreatic enzyme secretion. Secretin stimulates bicarbonate
secretion, gastrin stimulates acid secretion, and ghrelin stimulates appetite.
