GI Flashcards
Why do stem cells stain darker?
Bigger and more active nuclei
Describe the muscle of the oesophagus
Top 1/3 is voluntary muscle in fascicles
Middle 1/3 is mixed
Distal 1/3 is involuntary smooth muscle
Where are mucous glands found?
Submucosa= submucosal glands
Lamina propria= superficial glands
List the cells found in the lamina propria
Fibroblasts, lymphocytes, plasma cells, macrophages, eosinophils, mast cells
What is found in the sub mucosa?
Blood vessels, lymph vessels, nerves
What is the mucosa?
Epithelium + lamina propria+ muscularis mucosa
What is Barrett’s oesophagus?
Epithelial metaplasia of the oesophagus
Injury to the mucosa from GORD leads to a change from non keratinised strat squamous epithelia to glandular simple columnar
What is Barrett’s oesophagus?
Epithelial metaplasia of the oesophagus
Injury to the mucosa from GORD leads to a change from non keratinised strat squamous epithelia to glandular simple columnar
What are the 4 areas of the stomach called?
Cardia, fundus, body and pylorus
What cell types are found in stomach glands?
Epithelial cells, parietal cells (HCl and intrinsic factor) chief cells (pepsinogen and gastric lipase) enteroendocrine cell
How do you identify parietal cells and chief cells?
Parietal- lumpy, paler cells
Chief- look columnar like epithelium but dark with granules
How do you identify parietal cells and chief cells?
Parietal- lumpy, paler cells
Chief- look columnar like epithelium but dark
What factors can lead to ulcer formation?
Increased acidity
decreased mucous
diet
decreased prostglandins (due to NSAIDs?)
What factors can lead to ulcer formation?
Increased acidity
decreased mucous
diet
decreased prostaglandins (due to NSAIDs?)
Describe the villi of the small intestine
Duodenum- leaf like villi
Jejunum- fine tall villi
Ileum- finger like villi
What are the 3 features of the small intestine to increase absorption
Villil microvilli, circular folds (plicae circulares)
What are the intestinal crypts also called?
Crypts of Lieberkuhn
Function of paneth cells?
Contain antimicrobial granules (of defensins) and contribute to host-defence and the maintenance of the GI barrier. Found at base of crypts. Stain darkly eosinophilic
Name the cells of the epithelium of the small intestine
Goblet cells, enterocytes, enteroendocrine cells and paneth cells.
What is a Peyer’s patch?
Aggregation of lymphoid tissue, found in ileum and appendix (nodules of lymphoid follicles)
Lymphoid aggregates and the darker stained B cell aggregates
How does the pyloric region of the stomach differ from the fundic region of the stomach?
Fundus- long narrow glands Pylorus- deeper pits, shorter more branched glands, fewer parietal cells, mainly mucous secreting cells G cells (gastrin) and serotonin and somatostatin secreting cells
What are G-cells? + function
G-cells are enteroendocrine cells of the pyloric region of the stomach
Gastrin secreting cells
What are Brunner’s glands?
Submucosal glands of the proximal duodenum, secrete alkaline mucus to counteract acidity of chyme and lubricate walls
What is a Peyer’s patch?
Aggregation of lymphoid tissue, found in ileum and appendix
Lymphoid aggregates and the darker stained B cell aggregates
How does the pyloric region of the stomach differ from the fundic region of the stomach?
Fundus- long narrow glands
Pylorus- deeper pits, shorter more branched glands, fewer parietal cells
What are G-cells? + function
G-cells are enteroendocrine cells of the pyloric region of the stomach
Gastrin secreting cells
Difference between colon and rectum?
Rectum’s crypts are much longer and are almost entirely formed of goblet cells
Why is less mucus produced in the colon?
Less acid so less damage, don’t need mucus protection
Function of colon is mainly water absorption
Difference between Crohn’s and ulcerative colitis ulcers?
Croh’s- transmural
UC- only mucosal
What is the appendix?
Blind ended diverticulum extending from caecum
Difference between colon and rectum?
Rectum’s crypts are much longer and are almost entirely formed of goblet cells
What do myoepithelial cells do in glands?
Surround the gland and squeeze it to aid in secretion
Why are liver lobules split into zones?
Based on distance from portal triad
Zone 3 is furthest from blood supply and closest to central vein so more susceptible to hypoxia
What salivary gland is both mucous and serous secreting?
Submandibular
What are the main functions of zone 1 hepatocytes?
Gluconeogenesis, B-oxidation of fatty acids, bile acid secretion
What is the space surrounding the sinusoids of the liver called? What does it contain?
Space of Disse, contains collagen, fibrin and stellate cells
Why are liver lobules split into zones?
Based on distance from portal triad
Zone 3 is furthest from blood supply and closest to central vein so more susceptible to hypoxia
How do you identify the endocrine parts of the pancreas?
Islet of langerhans stain more paley
What are the main functions of zone 1 hepatocytes?
Gluconeogenesis, B-oxidation of fatty acids, bile acid secretion
Where in the liver does paracetamol injury and alcohol induced fibrosis occur?
Zone 3
What is the function of most of the pancreas?
Exocrine secretions of digestive proenzymes- pancreatic lipase, DNase, trypsinogen, elastase etc
How do you identify the endocrine parts of the pancreas?
Islet of langerhans stain more paley
What are trefoil factors?
Proteins that aid barrier repair and would healing
What cells are found above peyer’s patches?
M-cells (microfold cells)
Transport proteins, viruses and bacteria from gut lumen to antigen presenting cells in basal layer
Name the 2 lines that reflect a change in the epithelium in the rectum and anal canal
Dentate/pectinate line and Hilton’s white line
Function of anal sinuses
Secrete mucus, found just above anal valves
What is the dentate line also called? What does it signify?
Pectinate line
Divides the upper two thirds and lower third of the anal canal. Developmentally, this line represents the hindgut-proctodeum junction (non kerat->kerat st sq epithelium)
What is Hilton’s white line?
Hilton’s white line is slightly below the pectinate line, a landmark for the intermuscular border between internal and external anal sphincter muscles.
What is the innervation of each anal sphincter?
Internal= pelvic splanchnic nerves (S4) symp+parasym External= S4 + pudendal nerve
Describe the parts of the GI tract with ‘abnormal’ muscularis externa
Oesophagus= longitudinal only Stomach= inner oblique->circular->outerlongitudinal
Describe the parts of the GI tract with ‘abnormal’ muscularis externa
Oesophagus= longitudinal only Stomach= inner oblique->circular->outerlongitudinal
What can enteroendocrine cells produce? Where are they secreted?
Glucagon, somatostatin, serotonin, substance P, histamine, gastrin, CCK, GIP, VIP, neurotensin, secretin
Secreted into lamina propria
What do chief cells produce?
Pepsinogen, renin and gastric lipase
Name the 2 lines that reflect a change in the epithelium in the rectum and anal canal
Dentate/pectinate line and Hilton’s white line
What do chief cells produce?
Pepsinogen, renin and gastric lipase
How do you tell if glands are mucous or serous secreting?
Mucous is lightly stained, serous is darkly stained
What 4 vessels are you looking for in a liver slide?
Hepatic portal vein, bile duct and hepatic artery = triad
Central vein
Cell type of gall bladder wall?
Simple columnar with abundant microvilli
Cell type of gall bladder wall?
Simple columnar with abundant microvilli
Risk factors for gall stones?
Fat, fair, forty, fertile, female
What stains basophilic in pancreatic exocrine cells?
The zymogen granules near the nucleus
What is the function of exocrine pancreatic secretions?
Enzyme rich alkaline fluid to digest proteins, carbs, lipids and nucleic acids
How can gallstones cause pancreatitis?
Bile duct goes through pancreas and pancreatic duct and bile duct meet, could obstruct both with gall stones
Whats the most common cause of pancreatitis?
Excessive alcohol consumption
What do the endocrine cells of the pancreas produce?
ß cells- insulin α cells- glucagon ∂ cells- somatostatin G cells- gastrin PP cells- pancreatic polypeptide
How are the hepatocytes separated from thr sinusoidal lining cells?
By the perisinusoidal space= space of Disse
What are the macrophages of the liver called?
Kupffer cells
