Block 7 Histology

Question 1

What are the three types of mucosa in the oral cavity and where are they located?

Answer 1

1. Non-keratinized stratified squamous epithelium (inner surface of lips, cheeks, soft palate, surface of tongue, floor of mouth)
2. Keratinized stratified squamous epithelium (gingiva and hard palate)
3. Specialized mucosa with papillae (anterior 2/3 of tongue)

Question 2

What are the 4 broad layers of all components of the digestive tract?

Answer 2

1. Mucosa
2. Submucosa
3. Muscularis externa
4. Serosa/adventitia

Question 3

What are the components of the mucosa of the digestive tract?

Answer 3

1. Epithelium
2. Lamina propria
3. Muscularis mucosa

Question 4

What type of epithelium is found in the digestive tract?

Answer 4

Simple columnar, except for the esophagus and anal canal, which have stratified squamous cells

Question 5

What are the components of the submucosa of the digestive tract?

Answer 5

1. Connective tissue
2. Vessels
3. Meissners plexus
4. Mucus glands (sometimes)

Question 6

What are the components of the muscularis externa of the digestive tract?

Answer 6

1. 2-3 layers of smooth muscle (plus skeletal muscle in esophagus)
2. Myenteric (Auerbach) plexus between muscle layers

Question 7

What is the difference between the serosa and adventitia?

Answer 7

Serosa is covered by mesothelium and is intraperitoneal

Adventitia is not covered by mesothelium and is retroperitoneal

Question 8

What happens at the GEJ?

Answer 8

Change from stratified squamous epithelium to simple columnar epithelium

Question 9

Describe the components of the cardia of the stomach.

Answer 9

Glands contain mucus-secreting cells, stem cells, enteroendocrine cells, and occasional parietal cells

Question 10

Describe the components of the fundus and body of the stomach.

Answer 10

Fundic/gastric glands contain parietal cells and chief cells with some stem cells, mucus cells, and enteroendocrine cells

Question 11

Describe the components of the pylorus of the stomach?

Answer 11

Glands primarily contain mucus-secreting cells and 2 endocrine cells (gastrin-secreting G-cells and somatostatin-secreting D-cells)

Question 12

What is secreted by parietal cells? What do they look like?

Answer 12

HCl; large, round cells with centrally positioned nuclei, fried egg appearance, pale cytoplasm; more numerous in superior half of fundic glands

Question 13

What is secreted by chief cells? What do they look like?

Answer 13

Zymogen granules containing pepsinogen; small, columnar cells, darkly stained cytoplasm, nuclei located at base of cells, more numerous in inferior half of fundic glands

Question 14

What are the components of the small intestine?

Answer 14

Villi, microvilli, glands/crypts of Lieberkuhn, paneth cells, submucosa, Meissner plexus, etc.

Question 15

Where are the glands/crypts of Lieberkuhn in the SI and what do they contain?

Answer 15

Lamina propria, open into the mucosa at the base of the villi

Contain paneth cells, which contain pink granules and secrete lysozymes, TNF-alpha, and defensins

Question 16

What are the three sections of the SI and what are their unique components?

Answer 16

1. Duodenum: Brunner glands
2. Jejunum: long villi, increased goblet cells, NO Brunner glands, NO Peyer patches
3. Ileum: short villi, many goblet cells, Peyer patches

Question 17

What is the role of Brunner’s glands?

Answer 17

Produce mucus to protect the duodenal wall form stomach acid; also secrete HCO3- ions

Question 18

What are the three level of folds in the SI?

Answer 18

1. Plica circularis (gross folds)
2. Villi
3. Microvilli

Question 19

Describe the components of the large intestine.

Answer 19

Mucosa: large lumen, no villi, glands of Lieberkuhn, many goblet cells, no paneth cells
Submucosa: no glands
Muscularis externa: inner circular muscle + outer longitudinal muscle with Auerbach plexus

Question 20

What is the tenia coli?

Answer 20

The outer longitudinal muscle of the LI that forms three narrow bands

Question 21

What are unique features of the appendix?

Answer 21

Small, irregular lumen

Many lymphatic nodules in the mucosa

Question 22

Describe the epithelial shift at the anal-rectal junction.

Answer 22

Simple columnar to stratified squamous

Question 23

Describe the exocrine pancreas.

Answer 23

Contains many serous secretory pancreatic acinar cells; secretions are carried by the main duct to join the bile duct at the ampulla in the duodenum; contain zymogen granules

Question 24

Describe the endocrine pancreas.

Answer 24

Contains islets of Langerhans, which produce insulin and glucagon, which are released directly into the bloodstream (no duct system)

Question 25

Describe the liver in terms of lobules.

Answer 25

Hexagon with central vein in the center, hepatocytes radiating outward, portal tracts (PV, HA, BD) at the vertices

Question 26

Describe the liver in terms of acini.

Answer 26

Contains the hepatocytes served by a single branch of the hepatic artery; zone 1 contains hepatocytes closest to the hepatic artery and zone 3 contains hepatocytes closest to the central vein

Question 27

How can you distinguish between the portal vein, hepatic artery, and bile duct?

Answer 27

Portal vein: larger
Hepatic artery: thicker wall with more smooth muscle
Bile duct: lined by cuboidal epithelium

Question 28

Hepatocytes lie in ___ cords with sinusoids between them. What are sinusoids?

Answer 28

Anastomosing; vascular spaces lined by fenestrated endothelium

Question 29

What are Kupffer cells?

Answer 29

Macrophages of the liver found in the sinusoids

Question 30

What is the space of Disse?

Answer 30

Space between hepatocyte and sinusoid; contains connective tissue and reticulin fibers, as well as stellated cells, which store vitamin A

Question 31

Describe the biliary tract.

Answer 31

Bile caniliculi form bile ducts, which form the R and L hepatic duct. These form the common hepatic duct. From here, bile, can go to the cystic duct (to the gallbladder) or to the common bile duct