Trans - GI Histology Flashcards
Germ layer origin of the proctodeum and stomodeum
Ectoderm
Germ layer origin of the gut
Endoderm, except for proctodeum and stomodeum
Area of referred pain from the foregut
Epigastric region
Area of referred pain from the midgut
Periumbilical region
Area of referred pain from the hindgut
Hypogastric region
Embryonic precursor of foregut
Preenteron
Embryonic precursor of midgut
Mesenteron
Embryonic precursor of hindgut
Metenteron
Layers of the gut from internal to external
- Mucosa
- Submucosa
- Muscularis externa / tunica muscularis
- Serosa / adventitia
Meissner’s plexus is located in the:
Submucosa
Meissner’s plexus: function
Parasympathetic innervation to control contraction of the GIT
Auerbach’s plexus is located in the:
Tunica muscularis
Auerbach’s plexus: function
Sympathetic and parasympathetic motor innervation to tunica muscularis
Difference of serosa and adventitia
Serosa – with mesothelium (peritoneal or mesothelial pleura)
Adventitia – without mesothelium, lining is continuous with tissues or organs
Most numerous tongue papillae
Filiform
Least numerous tongue papillae
Circumvallate
Separates anterior and posterior tongue
Sulcus terminalis
What glands are associated with the circumvallate papillae?
Glands of von Ebner
Glands of von Ebner: function
Lubrication, solvent for dissolving food
Epithelium of oropharynx
Stratified squamous nonkeratinizing
Epithelium of esophagus
Stratified squamous thinly keratinized epithelium
Composition of muscularis externa in esophagus
Varying depending on segment
Upper 1/3 – purely striated
Middle 1/3 – mixed striated and smooth
Lower 1/3 – purely smooth
Process by which undamaged cells from the bottom of the gastric pits migrate to denuded basal lamina
Mucosal restitution
How to histologically differentiate the different parts of the stomach
The different parts of the stomach vary only in mucosal glands
Longitudinal folds in stomach
Rugae
Depressions in rugae lining the entire stomach
Gastric pits / foveolae
Epithelium of stomach
Simple columnar
3 layers of muscularis externa in stomach
- Longitudinal – outermost, complete at pylorus
- Circular – middle, complete, forms pyloric sphincter
- Oblique – innermost, incomplete, thickest at cardia
Where are the gastric oxyntic glands found?
Gastric fundus and body
Cells in gastric oxyntic glands
- Mucus neck cells
- Chief cells
- Parietal / oxyntic cells
- Enteroendocrine / GI endocrine cells / APUD cells
- Stem cells
Mucus neck cells: function
Secrete mucus for protection and lubrication
Chief cells: function
Secrete pepsinogen
Parietal cells: function
Secrete HCl and gastric intrinsic factor (for absorption of Vit. B12)
APUD cells: function
Produce hormones which influence activity of other cells in the stomach
APUD stands for
APUD – Amine Precursor Uptake Decarboxylase
Most numerous cells in gastric oxyntic glands
Chief cells
Most conspicuous cells in gastric oxyntic glands
Parietal cells
Cardiac glands: appearance, location
Slender, tubular, branched at lower end
Located near gastroesophageal junction
Pyloric glands: appearance, location, function
Tortuous, branched, larger lumen
Found in deep foveolae of pylorus
Secrete mucus and lysozyme
Crescentic folds of mucosa and submucosa in intestine
Plicae circulares / Valves of Kerkring
Plicae circulares are most abundant in ________ and least in ______
Most abundant – jejunum
Least abundant – ileum
Structure of villi
Mucosal projections with a core of lamina propria, smooth muscle, central lamina
Villi are most numerous in ________
Duodenum and proximal jejunum
Striated border of absorptive cells
Microvilli
Special features of adluminal surface of absorptive cells
Secrete protein hydrolases, disscaccharidases, carrier proteins
Special features of basolateral surface of absorptive cells
Na-K ATPase, receptors
Invaginations between bases of villi extending to muscularis mucosa
Crypts of Lieberkuhn
Part of the intestine with the highest turnover rate
Jejunum (3-6 days)
The upper half of the crypts of Lieberkuhn is (a)________, while the lower half contains (b)________
Continuous with villi epithelium
Stem cells and Paneth cells
Paneth cell – function
Immunological due to presence of lysosomes
Confluent lymphoid follicles in the terminal ileum
Peyer’s patches
Specialized epithelial cells overlying lymphoid follicles
M cells
Brunner’s gland – location, function
Located in duodenum, secrete alkaline mucus and epithelial growth factor (modulates parietal cell secretion and rate of cell proliferation)
The muscularis externa is thickened at the terminal ileum to form the:
Ileocecal sphincter
Only beneficial substances in the large intestine
Water, electrolytes, vitamin K
T/F: There is an increase in the number of goblet cells in the more distal portions of the large intestine
T
Shallow sacculations in the colon
Haustrae
T/F: The longitudinal muscle layers of the ascending, transverse, and descending colons are incomplete
T. It is concentrated into the taenia coli
Enumerate the taenia coli
- Free
- Mesenteric
- Omental
Accumulations of adipose tissue in the serosa/adventitia of the colon
Appendices epiploicae
Serosa is found in which regions of the colon
Anterior regions of the ascending, descending, and transverse colons
Dilated lower portion of the rectum
Rectal ampullae
T/F: The longitudinal muscle layer of the entire large intestine is incomplete
F. Taenia coli disappear at the level of the rectum
T/F: Rectum has more serosa than adventitia
F
Longitudinal mucosal folds in the anus
Columns of Morgagni
What anal sphincter is voluntary?
External anal sphincter
What anal sphincter is involuntary?
Internal anal sphincter
Most common location of the appendix
Retrocecal
The appendix has a (thick/thin) submucosa, and a (thick/thin) muscularis
Thick submucosa
Thin muscularis
Fibrous tissue capsule around the liver
Glisson’s capsule
Von Kupffer cells – function
Phagocytic cells that eliminate damaged RBCs and bacteria
Beginning of bile drainage system
Bile canaliculus
Space between hepatocyte and sinusoid
Space of Disse
Space of Disse – function
Space where non bile products such as albumin and fibrinogen are released
Classical lobule
Anatomic concept:
Hexagonal structure
Central point is central vein
Portal triad is found in corners
Portal lobule
Physiologic concept
Triangular structure
Center is portal triad
Central veins found in corners
Special features of zone 1 and zone 3 of hepatic acinus
Zone 1 receives most oxygenated blood
Zone 3 most affected by drugs, lipid accumulation
Diverticulum of common hepatic duct on visceral surface of the liver
Gallbladder
Folding of mucous membrane at the junction of the neck of the gallbladder and the cystic duct
Spiral valve of Heister
Outpocketings near the neck of the gallbladder that may be a consequence of inflammation, absent in newborns
Rokitansky-Aschkoff sinuses
T/F: The gallbladder has no muscularis mucosa but has a distinct submucosa
F. It has no muscularis mucosa and no distinct submucosa
Function of the pancreas
Exocrine – secretion of pancreatic juice
Endocrine – secretion of insulin and glucagon
Initial portion of pancreatic ductal system
Centroacinar cells
T/F: Pancreatic cells are highly eosinophilic
F. They are mostly basophilic
Pathway of pancreatic juice from acinus to pancreatic duct
Acinus –> intercalated duct –> intralobular duct –> interlobular duct –> pancreatic duct
T/F: The pancreas has no striated ducts
T
Salivary duct of parotid
Stensen’s duct
Salivary duct of submandibular gland
Wharton’s duct
Salivary duct of sublingual gland
Duct of Rivinus
Where does the Stensen’s duct open
Opposite 2nd upper molar
Where do the duct of Rivinus and the Wharton’s duct open
Mouth floor
Type of secretion: parotid
Mucous
Type of secretion: submandibular
Mixed
Type of secretion: sublingual
Serous
Histological appearance of mucous salivary gland
Single layer of plump pyramidal cells, nucleus displaced to base due to mucin
Histological appearance of serous salivary gland
Columnar/truncated pyramidal cells, apical cytoplasm filled with secretory granules
Histological appearance of mixed salivary gland
Proximal mucous cells covered with a distal crescentic cap of dark staining serous demilunes
Path of saliva through salivary ducts (from inside to out)
Intercalated –> striated –> interlobular –> main
Intercalated salivary duct – epithelium
Low cuboidal
Main salivary duct – epithelium
Stratified columnar
Striated salivary ducts – cause of striations
Vertically oriented mitochondria of cells
Striated salivary ducts – epithelium
Tall columnar epithelium