Histology Testbank: Gastrointestinal System 5a

Instructions: For each histology question, pick the one best answer. This histology test bank is also useful for the histology questions on the USMLE (USMLE step 1).

1.
Which layer of the gastrointestinal tract contains the gut associated lymphatic
tissue?
a. Mucosa
b. Submucosa
c. Muscularis externa
d. Muscularis mucosae
e. Serosa

Answer: a

The layers of the GI tract are: mucosa, submucosa, muscularis externa, and serosa or adventitia.

The mucosa is the innermost layer of the GI tract. The mucosa consists of a lining epithelium, lamina propria and muscularis mucosae. Gut associated lymphatic tissue (GALT) is found in the mucosa and sometimes extends into the submucosa.

The submucosa is comprised of dense irregular connective tissue. Within the submucosa are lymphatic vessels and nerve plexuses. Meissner's plexus is located in the submucosa.

The muscularis externa consists of thick layers of smooth muscle. The myenteric plexus of Auerbach is located in the muscularis externa.

The outer layer of the GI tract is either an adventitia or serosa. The serosa consists of only a single layer of epithelial cells (mesothelium) and underlying connective tissue. The adventitia is the outer layer of the GI tract when it is abutting another organ the posterior abdominal wall.

2.
Which cells secrete pepsinogen?
a. Parietal cells
b. Oxyntic cells
c. Chief cells
d. Mucous neck cells
e. Both a and b

Answer: c

Chief cells secrete pepsinogen. Pepsinogen is the precursor for pepsin. Parietal cells are also called oxyntic cells. They secrete hydrochloric acid and intrinsic factor. Mucous neck cells contain mucinogen granules.

3.
Which layer contains Meissner's plexus?
a. Mucosa
b. Sub mucosa
c. Muscularis externa
d. Serosa
e. Adventitia

Answer: b

The mucosa is the innermost layer of the GI tract. It consists of epithelium, lamina propria, and muscularis mucosa.

The submucosa is connective tissue. Within it are lymphatic vessels and nerve plexuses. Meissner's plexus is located in the submucosa.

The muscularis externa consists of thick layers of smooth muscle. It contains Auerbach's plexus.

The outer layer of the GI tract is either an adventitia or serosa. The serosa consists of only a single layer of epithelial cells and underlying connective tissue. The adventitia is the outer layer of the GI tract when it is abutting another organ the posterior abdominal wall.

4.
What type of tissue lines most of the gastrointestinal tract?
a. Simple squamous epithelium
b. Simple cuboidal epithelium
c. Simple columnar epithelium
d. Stratified squamous epithelium
e. Transitional epithelium

Answer: c

The lining of the gastrointestinal tract is simple columnar epithelium. Epithelium lines body cavities and surfaces. Simple columnar epithelium is "simple" because it is one cell thick. "Columnar" cells are taller than they are wide and have an oval nucleus.

5.
What type of tissue lines the upper esophagus?
a. Simple squamous epithelium
b. Simple cuboidal epithelium
c. Simple columnar epithelium
d. Stratified squamous epithelium
e. Transitional epithelium

Answer: d

The lining of the upper esophagus is stratified squamous epithelium. Epithelium lines body cavities and surfaces. Stratified squamous epithelium is "stratified" because it is more than one cell layer thick. "Squamous" refers to the fact that the surface cells of the layer are flat.

6.
What are the modifications of the muscularis externa that is seen on the large intestine?
a. Teniae coli
b. Crypts of Lieberkuhn
c. Plicae circulares
d. Striated border
e. Villi

Answer: a

The modifications of the muscularis externa seen on the large intestine are called teniae coli.

The lymphatic capillary within a villus of the small intestine is a lacteal.

Crypts of Lieberkuhn are the intestinal glands.

The plicae circulares is a projection with a core of submucosa. The plicae circulares is also called the valve of Kerckring.

Microvilli that are seen on the epithelial cells in the small intestine form the brush
border or striated border.

Villi are finger like projections of mucosa seen in the small intestine.

7.
Where are Brunner's glands located?
a. Esophagus
b. Stomach
c. Small intestine
d. Large intestine
e. Rectum

Answer: c

Brunner's glands are glands in the submucosa of the small intestine.

8.
What is the primary cell of the intestinal epithelium of the large intestine?
a. Columnar absorptive cell
b. Goblet cell
c. Parietal cells
d. Paneth cells
e. Chief cells

Answer: a

The major cell of the lining epithelium of the large intestine is the columnar absorptive cell.

9.
Which region are goblet cells most numerous?
a. Esophagus
b. Stomach
c. Small intestine
d. Large intestine
e. Anus

Answer: d

Goblet cells are most numerous in the large intestine

10.
Where is mesothelium found?
a. Mucosa
b. Sub mucosa
c. Muscularis externa
d. Serosa
e. Adventitia

Answer: d

The layers of the GI tract are: mucosa, submucosa, muscularis externa, and serosa or adventitia.

The mucosa is the innermost layer of the GI tract. The mucosa consists of a lining epithelium, lamina propria and muscularis mucosae. Gut associated lymphatic tissue (GALT) is found in the mucosa and sometimes extends into the submucosa.

The submucosa is comprised of dense irregular connective tissue. Within the submucosa are lymphatic vessels and nerve plexuses. Meissner's plexus is located in the submucosa.

The muscularis externa consists of thick layers of smooth muscle. The myenteric plexus of Auerbach is located in the muscularis externa.

The outer layer of the GI tract is either an adventitia or serosa. The serosa consists of only a single layer of epithelial cells (mesothelium) and underlying connective tissue. The adventitia is the outer layer of the GI tract when it is abutting another organ the posterior abdominal wall.