GI/Liver: Histology

Question 1

Describe the epithelium of the oral cavity.

Answer 1

Stratified squamous epithelium; keratinised or non-keratinised depending on if exposed to friction.

Question 2

Which parts of the oral cavity are non-keratinised?

Answer 2

Buccal mucosa (cheeks), floor of mouth, and ventral tongue (underside).

Question 3

What are the most common type of papillae on the tongue? What do they do to the surface of the tongue?

Answer 3

Filiform papillae (pointy).
Roughen the surface of the tongue.

Question 4

What sort of epithelium lines the ducts of the salivary glands?

Answer 4

Simple cuboidal epithelium (can become stratified at distal end or in larger ducts).

Question 5

What histological layers make up the mucosa of the gut?

Answer 5

Epithelium, lamina propria, and muscularis mucosae.

Question 6

What is the muscularis mucosae?

Answer 6

Layer of smooth muscle cells, makes up part of the mucosa of the gut/stomach.

Question 7

Why is the stomach’s muscularis propria layer different to the rest of the GI tract muscularis propria?

Answer 7

It has 3 layers of muscle instead of 2.

Question 8

What sort of epithelium lines the oesophagus?

Answer 8

Stratified squamous non-keratinising epithelium.

Question 9

What sort of epithelium lines the stomach/intestines?

Answer 9

Simple cuboidal epithelium

Question 10

Which part of the stomach produces HCl and enzymes?

Answer 10

Fundus and body (not antrum!)

Question 11

What is the name of the absorptive cells in the intestine?

Answer 11

Enterocytes.

Question 12

Name the two nerve plexuses which run from the oesophagus to the rectum.

Answer 12

Meissener’s (submucosal) plexus and Auerbach’s (myenteric) plexus.

Question 13

How can you tell the difference between duodenum, jejunum, and ileum histologically?

Answer 13

Presence of Brunner’s glands (duodenum has them, jejunum and ileum do not).
Presence of Peyer’s patches (ileum has them, duodenum and jejunum do not).

Question 14

Why are Brunner’s glands important in the duodenum?

Answer 14

To produce alkaline secretion to neutralise chyme coming from the stomach.

Question 15

What are Paneth cells?

Answer 15

Cells in the small intestine which secrete lysozyme to break down bacteria, regulating bacteria flora of the gut. Stain bright pink in H&E.

Question 16

What are Peyer’s patches?

Answer 16

Lymphoid tissue in submucosa of ileum, can erupt through the muscularis mucosa.

Question 17

Does the appendix have a muscularis mucosa?

Answer 17

No.

Question 18

What is the difference between the epithelium of the rectum and the anal canal?

Answer 18

Rectum = simple columnar epithelium.
Anal canal = stratified squamous keratinising epithelium.

Question 19

What are the three key components of a portal tract?

Answer 19

Portal vein branches
Hepatic artery branches
Bile ducts

Question 20

What is a classic lobule of the liver?

Answer 20

A polygonal/hexagonal area of the liver drained by one central hepatic venule (artificial construct).

Question 21

What is an acinus of the liver?

Answer 21

A diamond-shaped area of the liver, supplied by two portal tracts, with the points of the diamond as two hepatic venules (artificial construct).

Question 22

Where in a classic lobule are hepatocytes that are more richly oxygenated?

Answer 22

Heptaocytes more distal to the central vein (therefore closer to the portal ducts on the outside edge).

Question 23

What are sinusoids?

Answer 23

Thin-walled wide-lumen fenestrated capillaries in the liver, running in between cords of hepatocytes.

Question 24

Describe a hepatocyte histologically.

Answer 24

Polyhedral epithelial cell with abundant mitochondria causing granulated cytoplasm.
Large central spherical nuclei with often prominent nucleoli, and can be binucleate.

Question 25

Where would you find reticulin fibres that make up the scaffold of the liver?

Answer 25

The space of Disse (the space in between sinusoidal endothelial cell and hepatocyte).

Question 26

What are the three surfaces of a hepatocyte membrane? Which is the largest surface area?

Answer 26

Sinusoidal - the largest! 70%
Canalicular
Intercellular

Question 27

What is the function of the canalicular surface?

Answer 27

To allow the hepatocyte to secrete bile into the canaliculi (first part of the bile system).

Question 28

Where would you find Kupffer cells?

Answer 28

In the endothelium of the sinusoids in the liver.

Question 29

What are two key functions of Kupffer cells?

Answer 29

Phagocytose and destroy blood borne pathogens.
Breakdown old erythrocytes, producing bilirubin.

Question 30

Describe the epithelium of bile ductules.

Answer 30

Simple cuboidal epithelium.

Question 31

What are the four parts of the intrahepatic biliary tree?

Answer 31

Canaliculi -> bile ductules -> trabecular ducts -> bile ducts.

Question 32

Why does the gallbladder have a simple columnar epithelium with microvilli and folds?

Answer 32

To increase surface area for reabsorption of water and salts, to concentrate bile.

Question 33

What do centroacinar and small duct cells of the pancreas produce when stimulated by secretin?

Answer 33

An alkaline fluid.

Question 34

What does stimulation with cholecystokinin cause in the pancreas?

Answer 34

Exocytosis/release of zymogen granules (containing digestive enzymes) from cells of the pancreas.

Question 35

What shape are pancreatic acinar cells?

Answer 35

Pyramidal.

Question 36

Describe the four parts of the pancreatic duct system.

Answer 36

Centroacinar cells -> intercalated ducts -> interlobular ducts -> main pancreatic duct.

Question 37

How does the transverse colon differentiate histologically from the caecum?

Answer 37

It doesn’t, can’t tell the difference between different parts of the colon histologically.