Histology Flashcards
Adventitia of gut may be lined by…
Serosa - layer of mesothelial cells resting on a basement membrane comprising the peritoneum
Oral cavity lined with…
Stratified squamous epithelium (robust so won’t tear away from sharp food)
Salivary glands lined by…
Secretory glandular epithelium
Sjorgen’s syndrome
Autoimmune disease where glandular epithelium are attacked by body lymphocytes resulting in no saliva (dry mouth)
Oesophagus lined by…
Squamous epithelium
Beneath it has submucosal glands which secrete mucous into lumen
Stomach lined by…
Gastric fundic mucosa (produce mucus)
Gastric body mucosa (contains parietal cells, chief cells
Gastric antral mucosa (less specialised and again produces mucus)
Small and large intestine lined by…
Glandular epithelium interspersed with endocrine cells
Layers of Bowel
Mucosa (glandular epithelium)
Submucosa (loose collagen connective tissue containing blood vessels)
Muscularis propria (2 layers, all smooth muscle, ganglion nerve cells sit between longitudinal and circular layers)
Serosal surface (mesothelial cells)
Interstitial cells of Cajal
Pacemaker cells of the muscular wall in the small intestine
Progenitors of gastrointestinal stromal tumours (GIST)
Crypts of the gut
U-shaped column like structures in the gut lining
Bottom of U - Stem cells divide keeping a copy of themselves at the bottom and the division creates a transit cell which is sent up to become a normal columnar epithelial cell lining the gut (apoptose eventually at top)
What is a crypt?
U-shaped “valley” between villi
What is MALT?
Mucosa-associated lymphoid tissue (found in mucosa of small intestine)
What are Giardia lamblia?
Bugs/parasites that sit on the mucosa of the small intestine giving people diarrhoea as absorption is harder
What occurs in the mucosa in coeliac’s disease?
Villus atrophy and crypt hyperplasia
Mucosa of colon?
Glandular, flat mucosa (no villi)
What comprises the liver epithelium?
Hepatocytes arranged in cords with intervening specialised blood vessels (sinusoids)
Portal tracts comprise…
Branches of portal vein, hepatic artery and the bile duct
And central veins
What is a classic lobule of the liver?
Area of the liver drained by one central hepatic venule (roughly hexagonal due to being surrounded by 6 portal tracts comprising bile duct, portal vein and hepatic artery branch)
What is an acinus of the liver
Area based around blood supply rather than blood drainage
Diamond shape (portal tracts at either end of the short axis and central veins at either end of the long axis)
What hepatocytes in the liver lobule are more richly supplied with oxygen?
Hepatocytes nearer the portal tracts (portal vein and hepatic artery) as blood from portal tracts travels through sinusoids to the central veins so hepatocytes closer to the central veins are more oxygen deprived
Features of hepatocytes in the liver
Polyhedral epithelial cells
Lots of mitochondria, large central spherical nuclei, prominent nucleoli,
3 important surfaces of hepatocyte
Sinusoidal (70%)
Canalicular (15%) (lies between hepatocyte and a bile canaliculus which drains bile secreted by hepatocyte into bile duct)
Intercellular (15%) (between adjacent hepatocytes)
What is contained within the Space of Disse?
Reticulin fibres and Ito cells (stem cell population in liver)
Sinusoids of liver structure
Fenestrated blood vessels lined with a thin vascular endothelium and no basement membrane
Contain phagocytic Kupffer cells (derived from blood monocytes)
Hepatocytes produce bile, what is then the path to the bile ducts?
Into canaliculi -> Bile ductules -> Fuse to form trabecular ducts -> Fuse to form bile ducts
What lines bile ducts? How does it change?
Simple cuboidal to columnar epithelium resting on a basement membrane (height of biliary epithelium increases as size of duct increases so extrahepatic duct epithelium longer than intrahepatic duct epithelium)
Gallbladder Function
Concentrate and store bile (absorbs water due to villi/microvilli)
Expel bile into duodenum via common bile duct
Gallbladder wall structure
Simple columnar epithelium resting on a basement membrane
Beneath is a mucosa of loose fibrous connective tissue
Beneath is a smooth muscle muscularis propria
Beneath is another layer of loose fibrous connective tissue (adventitia)
Exocrine Pancreas Role
Synthesise/secrete enzymes and bicarbonate-rich fluid into duodenum
What separates the pancreas into lobules?
A poorly defined fibrous capsule with septa which penetrate into the gland and separate it into lobules
Pancreatic epithelial cells arranged into…
Acini (containing acinar cells, centroacinar cells, cut cells)
Secretions of pancreatic acinar cells drain into duct system beginning with…
CENTROACINAR CELLS (located in centre of acini) which give rise to INTERCALATED DUCTS which fuse forming INTERLOBULAR DUCTS and then form the MAIN PANCREATIC DUCT
What are acinar epithelial cells?
Contained within acini of the liver
Pyramidal shape
Rich in RER
Contain lots of zymogens in the apex of the cell
How does the epithelium change from the interlobular ducts and the main pancreatic duct?
Goes from cuboidal to columnar
Approx how many nephrons in the kidney?
1 million
Myofibrils of skeletal muscle are arranged into…
Fascicles
Perimysium is…
Connective tissue surrounding fascicles of skeletal muscle tissue
Endomysium is…
Connective tissues lying between each fascicle
Epimysium is…
Connective tissue surrounding the muscle itself
Features of type 1 muscle fibres
Slow twitch (red fibres) Oxidative, fatigue, resistant
Features of type 2 muscle fibres
Fast twitch - fatigue rapidly but generate a large peak of muscle tension
2A - glycolytic and oxidative (intermediate)
2B - glycolytic (white)
What gives the mosaic pattern on a slide of skeletal cells (from an oxidative stain)?
Some cells appear darker when stained with oxidative stain as they’re more oxidative than glycolytic so produce more NADH
This is because different muscle cells in the same slide are supplied by different neurones
Energy for contraction
Comes from ATP
Immediate source of replenishment comes from a short term energy source: Creatine Phosphate
CP replenished by Creatine kinase (CK)
CK released on muscle fibre damage
What connects the actin-myosin complex to extracellular matrix proteins? (anchoring muscle fibre for stability)
Merosin (extracellular protein) linked to dystoglycan (transmembrane protein) which is linked to sarcoglycans also in the membrane
The membrane complex links to dystrophin inside the cell which connects to actin
Dystrophin function
Confer stability to muscle fibre membrane
