A&P 1 101 - Portage Learning
Module 3 Exam: The Digestive System
Questions & Rationale
Q1: Which layer of the digestive tract wall contains the blood vessels, lymphatic vessels,
and nerve fibers that supply the surrounding tissues?
A. Mucosa
B. Submucosa
C. Muscularis externa [CORRECT]
D. Serosa
Correct Answer: B
Rationale: The submucosa is the connective tissue layer deep to the mucosa that
houses the submucosal nerve plexus (Meissner's plexus), blood vessels, and lymphatic
vessels supplying the digestive tract wall. The mucosa (A) is the innermost epithelial
layer responsible for secretion and absorption. The muscularis externa (C) contains the
smooth muscle layers responsible for peristalsis and segmentation. The serosa (D) is
the outermost protective layer.
Q2: The peritoneal fold that suspends the small intestine from the posterior abdominal
wall and contains blood vessels, lymphatics, and nerves is called the:
A. Greater omentum
,B. Lesser omentum
C. Mesentery proper [CORRECT]
D. Falciform ligament
Correct Answer: C
Rationale: The mesentery proper specifically refers to the fan-shaped peritoneal fold
that attaches the jejunum and ileum of the small intestine to the posterior abdominal
wall, carrying the neurovascular supply. The greater omentum (A) drapes from the
stomach over the intestines like an apron. The lesser omentum (B) connects the
stomach and duodenum to the liver. The falciform ligament (D) attaches the liver to the
anterior abdominal wall and diaphragm.
Q3: Which structure prevents the reflux of stomach contents into the esophagus?
A. Pyloric sphincter
B. Lower esophageal sphincter (cardiac sphincter) [CORRECT]
C. Ileocecal valve
D. Upper esophageal sphincter
Correct Answer: B
Rationale: The lower esophageal sphincter (LES), also called the cardiac sphincter, is a
physiological sphincter at the gastroesophageal junction that prevents acidic stomach
contents from refluxing into the esophagus. Weakness of the LES causes
gastroesophageal reflux disease (GERD). The pyloric sphincter (A) controls gastric
, emptying into the duodenum. The ileocecal valve (C) prevents backflow from the large
intestine into the ileum.
Q4: Mechanical digestion through mastication is performed by which structures?
A. Tongue and soft palate
B. Teeth and tongue [CORRECT]
C. Pharynx and esophagus
D. Salivary glands and teeth
Correct Answer: B
Rationale: Mechanical digestion in the oral cavity involves teeth (cutting, tearing, and
grinding food into smaller particles) and the tongue (manipulating food into a bolus and
positioning it for swallowing). While salivary glands (D) contribute to chemical digestion
through enzyme secretion, they do not perform mechanical breakdown. The pharynx
and esophagus (C) are primarily conduits for food transport.
Q5: Salivary amylase (ptyalin) begins the chemical digestion of which macronutrient?
A. Proteins
B. Lipids
C. Carbohydrates [CORRECT]
D. Nucleic acids
Correct Answer: C
Module 3 Exam: The Digestive System
Questions & Rationale
Q1: Which layer of the digestive tract wall contains the blood vessels, lymphatic vessels,
and nerve fibers that supply the surrounding tissues?
A. Mucosa
B. Submucosa
C. Muscularis externa [CORRECT]
D. Serosa
Correct Answer: B
Rationale: The submucosa is the connective tissue layer deep to the mucosa that
houses the submucosal nerve plexus (Meissner's plexus), blood vessels, and lymphatic
vessels supplying the digestive tract wall. The mucosa (A) is the innermost epithelial
layer responsible for secretion and absorption. The muscularis externa (C) contains the
smooth muscle layers responsible for peristalsis and segmentation. The serosa (D) is
the outermost protective layer.
Q2: The peritoneal fold that suspends the small intestine from the posterior abdominal
wall and contains blood vessels, lymphatics, and nerves is called the:
A. Greater omentum
,B. Lesser omentum
C. Mesentery proper [CORRECT]
D. Falciform ligament
Correct Answer: C
Rationale: The mesentery proper specifically refers to the fan-shaped peritoneal fold
that attaches the jejunum and ileum of the small intestine to the posterior abdominal
wall, carrying the neurovascular supply. The greater omentum (A) drapes from the
stomach over the intestines like an apron. The lesser omentum (B) connects the
stomach and duodenum to the liver. The falciform ligament (D) attaches the liver to the
anterior abdominal wall and diaphragm.
Q3: Which structure prevents the reflux of stomach contents into the esophagus?
A. Pyloric sphincter
B. Lower esophageal sphincter (cardiac sphincter) [CORRECT]
C. Ileocecal valve
D. Upper esophageal sphincter
Correct Answer: B
Rationale: The lower esophageal sphincter (LES), also called the cardiac sphincter, is a
physiological sphincter at the gastroesophageal junction that prevents acidic stomach
contents from refluxing into the esophagus. Weakness of the LES causes
gastroesophageal reflux disease (GERD). The pyloric sphincter (A) controls gastric
, emptying into the duodenum. The ileocecal valve (C) prevents backflow from the large
intestine into the ileum.
Q4: Mechanical digestion through mastication is performed by which structures?
A. Tongue and soft palate
B. Teeth and tongue [CORRECT]
C. Pharynx and esophagus
D. Salivary glands and teeth
Correct Answer: B
Rationale: Mechanical digestion in the oral cavity involves teeth (cutting, tearing, and
grinding food into smaller particles) and the tongue (manipulating food into a bolus and
positioning it for swallowing). While salivary glands (D) contribute to chemical digestion
through enzyme secretion, they do not perform mechanical breakdown. The pharynx
and esophagus (C) are primarily conduits for food transport.
Q5: Salivary amylase (ptyalin) begins the chemical digestion of which macronutrient?
A. Proteins
B. Lipids
C. Carbohydrates [CORRECT]
D. Nucleic acids
Correct Answer: C
