GI/Liver: Histology Flashcards
Describe the epithelium of the oral cavity.
Stratified squamous epithelium; keratinised or non-keratinised depending on if exposed to friction.
Which parts of the oral cavity are non-keratinised?
Buccal mucosa (cheeks), floor of mouth, and ventral tongue (underside).
What are the most common type of papillae on the tongue? What do they do to the surface of the tongue?
Filiform papillae (pointy).
Roughen the surface of the tongue.
What sort of epithelium lines the ducts of the salivary glands?
Simple cuboidal epithelium (can become stratified at distal end or in larger ducts).
What histological layers make up the mucosa of the gut?
Epithelium, lamina propria, and muscularis mucosae.
What is the muscularis mucosae?
Layer of smooth muscle cells, makes up part of the mucosa of the gut/stomach.
Why is the stomach’s muscularis propria layer different to the rest of the GI tract muscularis propria?
It has 3 layers of muscle instead of 2.
What sort of epithelium lines the oesophagus?
Stratified squamous non-keratinising epithelium.
What sort of epithelium lines the stomach/intestines?
Simple cuboidal epithelium
Which part of the stomach produces HCl and enzymes?
Fundus and body (not antrum!)
What is the name of the absorptive cells in the intestine?
Enterocytes.
Name the two nerve plexuses which run from the oesophagus to the rectum.
Meissener’s (submucosal) plexus and Auerbach’s (myenteric) plexus.
How can you tell the difference between duodenum, jejunum, and ileum histologically?
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).
Why are Brunner’s glands important in the duodenum?
To produce alkaline secretion to neutralise chyme coming from the stomach.
What are Paneth cells?
Cells in the small intestine which secrete lysozyme to break down bacteria, regulating bacteria flora of the gut. Stain bright pink in H&E.
What are Peyer’s patches?
Lymphoid tissue in submucosa of ileum, can erupt through the muscularis mucosa.
Does the appendix have a muscularis mucosa?
No.
What is the difference between the epithelium of the rectum and the anal canal?
Rectum = simple columnar epithelium.
Anal canal = stratified squamous keratinising epithelium.
What are the three key components of a portal tract?
Portal vein branches
Hepatic artery branches
Bile ducts
What is a classic lobule of the liver?
A polygonal/hexagonal area of the liver drained by one central hepatic venule (artificial construct).
What is an acinus of the liver?
A diamond-shaped area of the liver, supplied by two portal tracts, with the points of the diamond as two hepatic venules (artificial construct).
Where in a classic lobule are hepatocytes that are more richly oxygenated?
Heptaocytes more distal to the central vein (therefore closer to the portal ducts on the outside edge).
What are sinusoids?
Thin-walled wide-lumen fenestrated capillaries in the liver, running in between cords of hepatocytes.
Describe a hepatocyte histologically.
Polyhedral epithelial cell with abundant mitochondria causing granulated cytoplasm.
Large central spherical nuclei with often prominent nucleoli, and can be binucleate.
Where would you find reticulin fibres that make up the scaffold of the liver?
The space of Disse (the space in between sinusoidal endothelial cell and hepatocyte).
What are the three surfaces of a hepatocyte membrane? Which is the largest surface area?
Sinusoidal - the largest! 70%
Canalicular
Intercellular
What is the function of the canalicular surface?
To allow the hepatocyte to secrete bile into the canaliculi (first part of the bile system).
Where would you find Kupffer cells?
In the endothelium of the sinusoids in the liver.
What are two key functions of Kupffer cells?
Phagocytose and destroy blood borne pathogens.
Breakdown old erythrocytes, producing bilirubin.
Describe the epithelium of bile ductules.
Simple cuboidal epithelium.
What are the four parts of the intrahepatic biliary tree?
Canaliculi -> bile ductules -> trabecular ducts -> bile ducts.
Why does the gallbladder have a simple columnar epithelium with microvilli and folds?
To increase surface area for reabsorption of water and salts, to concentrate bile.
What do centroacinar and small duct cells of the pancreas produce when stimulated by secretin?
An alkaline fluid containing bicarbonate ions.
What does stimulation with cholecystokinin cause in the pancreas?
Exocytosis/release of zymogen granules (containing digestive enzymes) from cells of the pancreas.
What shape are pancreatic acinar cells?
Pyramidal.
Describe the four parts of the pancreatic duct system.
Centroacinar cells -> intercalated ducts -> interlobular ducts -> main pancreatic duct.
How does the transverse colon differentiate histologically from the caecum?
It doesn’t, can’t tell the difference between different parts of the colon histologically.
In haemochromatosis, Kuppfer cells accumulate the pigment haemosiderin, which contains iron. What stain will show this as bright blue?
Perl’s stain (Prussian blue).
