Histology - Gastrointestinal Block Flashcards
What type(s) of epithelia is(are) found in the oral cavity?
(1) Non-keratinized stratified squamous (lining mucosa)
(2) Keratinized or para-keratinized stratified squamous (lining gingiva and hard palate)
(3) Specialized papillae and taste buds (dorsal tongue)
What are the three histological sections of the oral lip?
Describe each.
(1) Cutaneous, (2) vermillion/red, (3) oral mucosa
What muscle group is found in the lips?
Orbicularis oris
Name the histological lip region described: thin skin with tall dermal papillae (keratinized stratified squamous epithelium with hair follicles and sebaceous and sweat glands).
Cutaneous region
Name the histological lip region described: a stratified squamous epithelium supported by connective tissue containing blood vessels responsible for the red color of this region; no salivary glands
Vermillion/red region
Name the histological lip region described: stratified squamous epithelium, supported by a dense lamina propria and a submucosa, closely bound by connective tissue fibers to the underlying skeletal muscles.
Oral mucosa region
Name and describe the papillae of the tongue.
Filiform (most numerous) - covered by keratinized stratified squamous epithelium
Fungiform - same covering as filiform, mushroom-shaped, taste buds
Circumvallate - ducts of glands of von Ebner, side taste buds
Where are taste buds found in relation to the papillae of the tongue?
Within the circular cleft
Gustatory cells contact masticated food through:
Taste pores
What are the three types of cell in the tongue related to taste?
Gustatory
Supportive
Stem (basal)
What three precusor cells give rise to the teeth?
Ameloblast (enamel)
Odontoblast (dentin)
Cementoblast (cementum)
Name the respective product of each of the following cells:
Cementoblast
Ameloblast
Odontoblast
Cementum
Enamel
Dentin
What is the hard, outer layer of the tooth?
What lies just deep to this layer?
Enamel;
dentin
The _________ ligament secures the tooth to alveolar bone via the ligament’s interface with the tooth through ___________.
Periodontal;
cementum
Name the layers of the esophagus from the inner mucosa to the outermost layer (assume above the diaphragm).
Mucosa
- Epithelium*
- Lamina propria*
- Muscularis mucosa*
Submucosa
- Glands, blood vessels*
- Meissner’s plexus*
Muscularis externa
- Inner circular layer*
- Auerbach’s plexus*
- Outer longitudinal layer*
Adventitia
Serosa (below diaphragm)
What esophageal covering is only present below the diaphragm?
Serosa
True/False.
Contraction of the muscularis mucosae produces ___________ folds in the esophagus.
Longitudinal
What type of epithelium lines the esophageal lumen in a healthy esophagus?
Non-keratinized stratified squamous epithelium
The muscularis of the upper 1/3 of the esophagus is made of _________ muscle.
The muscularis of the upper 2/3 of the esophagus is made of _________ muscle.
The muscularis of the upper 3/3 of the esophagus is made of _________ muscle.
Striated;
striated + smooth;
smooth
Describe the glands of the esophagus.
Tubuloacinar glands arranged in small lobules that drain into a single duct
What type of gland is found in the esophageal mucosa?
What type of gland is found in the esophageal submucosa?
Cardiac mucus glands (lamina propria);
esophageal glands
From proximal to distal, what are the four general regions of the stomach?
Cardia,
fundus,
body,
pyloric antrum
The stomach lumen is lined by longitudinal folds called:
Rugae
Describe the three regions of the general anatomy of a gastric gland.
The pit (surface mucous cells),
the neck (pinch point),
the body (parietal, chief, neuroendocrine, and stem cells)
Describe the histology of a gastric gland.
Describe the histology and function of a gastric parietal cell.
Histology: microvillous, numerous cannaliculi and mitochondria
Function: secrete HCl and intrinsic factor
Describe the histology and function of a gastric chief cell.
Histology: apical zymogen granules, basal RER, supranuclear Gogli
Function: secrete pepsinogen
What are the four general layers found throughout the GI tract?
Mucosa,
submucosa,
muscularis externa,
serosa
From anatomically largest to smallest, name four mechanisms by which the small intestine increases its surface area.
Plicae circularis
Villi
Crypts of Lieberkuhn
Microvilli
Define: crypts of Lieberkuhn.
Invaginations of intestinal mucosa extending deep between villi
(at times, all the way down to the muscularis mucosae)
Describe the gastric epithelium.
Simple columnar
What is the difference between gastric mucous cells found on the luminal epithelium and those found in the neck of gastric glands?
Surface - insoluble mucus production
Glandular neck - soluble mucus production
What are some of the products secreted by enteroendocrine cells found in the body of gastric glands?
Cholecsytokinin,
secretin,
gastrin
True/False.
Both the gastric epithelium and the small intestinal epithelium are simple columnar.
True.
What are the five main cells of the small intestine?
Enterocytes
Goblet cells
Enteroendocrine cells
Paneth cells
Stem cells
What main function(s) do Paneth cells of the small intestine serve?
Release lysozymes, defensins, phospholipase A2;
regulate gut flora
What structure innervates/causes villous movement in the small intestine?
Central lacteals are located in what tissue layer?
The submucosal (Meissner’s) plexus;
the lamina propria
True/False.
Most small intestine lymphatics are in the lamina propria, and the central lacteals are located in the submucosa.
False.
Most small intestine lymphatics are in the submucosa, and the central lacteals are located in the lamina propria.
What function(s) is(are) regulated by the submucosal (Meissner’s) nerve plexus?
Mucosal / submucosal glands;
the muscularis mucosa
What function(s) is(are) regulated by the myenteric (Auerbach’s) nerve plexus?
Peristalsis
Describe the differences in villi shapes between the duodenum, jejunum, and ileum.
D: Leaf-like at apex
J: finger-like
I: shortest
Describe the differences in distinctive structures between the supportive networks of the duodenum, jejunum, and ileum.
D: Brunner’s glands (submucosa)
J: none
I: Peyer’s patches (lamina propria and submocusa)
What type of gland is found only in the duodenum?
Brunner’s glands
What type structure is found only in the ileum?
Peyer’s patches
(also, M cells)
What are M cells of the small intestine?
APCs of the ileal epithelium
Describe the relationship between M cells and Peyer’s patches.
What type of epithelium is found in the large intestine?
Simple columnar
What are the four cell types of the large intestine?
Enterocytes
Goblet cells
Enteroendocrine cells
Stem cells
What visible external structures are formed on the large intestine by the longitudinal layer of the muscularis externa?
The teniae coli
Identify which of the following are present in the large intestine:
Plicae circularis
Villi
Microvilli
Crypts of Lieberkuhn
Goblet cells
Plicae circularis
Villi
Crypts of Lieberkuhn
Microvilli
Goblet cells (in large number)
Besides the colon (ascending, transverse, descending, and sigmoid), what are the other portions of the large intestine?
The appendix,
the rectum,
the anal canal
At the base of what distal structure of the large intestine do the teniae coli converge and end?
The appendix
(note: they end at the base and do not extend onto the appendix)
Describe the lymphoid portion of the appendix.
Large aggregations in the lamina propria and submucosa
Describe the epithelium of the anal canal.
A transition from simple columnar to stratified squamous (with hair follicles and sebaceous glands)
Describe the general histological changes from the esophagus to the colon.
What form of vitamin D comes from the skin upon sun exposure?
D3
How does parathyroid hormone have an effect on vitamin D protein production?
Upregulation of 1-α-hydroxylase in the PCT
After calcium absorption is increased by vitamin D, what protein modulates calcium channels and pumps to prevent cytosolic buildup of calcium within the enterocytes?
Calbindin
What are our main sources of 25-hydroxy vitamin D?
Sun exposure;
diet
Vitamin D acts on what organ systems?
Bones;
the gut
What protein is secreted in the oral cavity and is necessary for vitamin B12 absorption?
Transcobalamin-1
(haptocorrin)
(R-factor)
What two substances must bind B12 in order for it to be properly carried to the absorption site?
What substance is necessary to cleave one of these substances and allow the B12 complex to be absorbed?
Transcobalamin-1 (oral cavity),
intrinsic factor (gastric body);
pancreatic lipases (cleave TC-1)
Vitamin B12 absorption occurs at:
Peyer’s patches (the terminal ileum)
True/False.
B12 deficiencies virtually only occur when there is either an insufficient diet or gastric damage.
False.
There are several other causes (see image).
What four layers are found throughout the digestive tract?
Mucosa
Submucosa
Muscularis externa
Adventitia/Serosa
What are the three portions of the gut mucosa?
Epithelium, lamina propria, muscularis mucosa
True/False.
Many small salivary glands and APCs can be found in the soft mucosa of the cheeks.
False.
Many small salivary glands and APCs can be found in the soft sub__mucosa of the cheeks.
In what directions do the intrinsic muscle fibers of the tongue project?
Where do they attach?
In various crisscrossing directions;
a central septum
Which type(s) of lingual papillae lack(s) taste buds?
Filiform
What type of lingual papilla is not abundant in adult humans?
Foliate
True/False.
The lingual circumvallate papillae contain mucinous secretions.
False.
The lingual circumvallate papillae contain serous secretions.
What are the three largest salivary glands?
Parotid, sublingual, and submandibular
What are the four smaller salivary glands?
Lingual, labial, buccal, palatine
The ___________ gland has many bilateral ducts beneath the tongue.
The ___________ gland has 1-2 ducts beneath the tongue.
Sublingual;
submandibular
True/False.
Salivary glands are often bunches of glands leading into a single duct.
True.
(Similar to a bunch of grapes on a stalk)
Cells secreting serous fluids are _______ly colored.
Cells secreting mucinous fluids are _______ly colored.
Dark;
light
The parotid gland is a completely _________ (serous/mucinous) gland.
Serous
The submandibular gland is a predominantly _________ (serous/mucinous) gland.
Serous
The sublingual gland is a predominantly _________ (serous/mucinous) gland.
Mucinous
What term describes diminished salivary secretion?
Xerostomia
Describe the chemical/substrate makeup of saliva.
Water,
calcium,
phosphate,
amylase (and other proteins),
IgA,
electrolytes
Mumps
The gastric cardia contains ________ glands.
The gastric fundus contains ________ glands.
The pyloric region contains ________ glands.
Cardiac;
gastric;
pyloric
What enzyme allows h. pylori to resist the acidic gastric pH?
Urease
What effect does acetylcholine (parasympathetic stimulation) have on gastric glands?
Increased parietal cell secretion (HCl and intrinsic factor);
increased enteroendocrine secretion (histamine and gastrin)
Describe the differences in histological appearance between neck mucus cells, parietal cells, and chief cells.
Neck mucus cells - flat, pale, near gland neck;
parietal cells - eosinophilic, round, cannalicular;
chief cells - basophilic, round, towards deepest portion of gland
True/False.
Enteroendocrine cells of the stomach can secrete a variety of hormones, including the following:
gastrin, histamine, glucagon, serotonin, somatostatin
True.
What is the difference between a ‘closed’ and an ‘open’ enteroendocrine cell of the stomach?
Closed do not reach the gastric lumen (contacting the blood vessels only);
open reach the lumen
What substance plays a major role in alkalizing gastric mucus?
Bicarbonate
Besides pepsinogen, what do gastric chief cells also produce?
Gastric lipase
How often do surface mucus cells of the stomach regenerate from stem cells?
Every 3 - 5 days
What segments of the GI tract contain paneth cells?
Mainly the jejunum
Describe the appearance of Paneth cells (found in the jejunum).
What type of cell is found only in the jejunum and helps regulate gut flora?
Paneth cells
True/False.
If you see a section of small intestine with abundant lymphocytes, that must be the ileum.
False.
Abundant GALT with germinal centers is more indicative of Peyer’s patches.
Which section of the small intestine contains abundant submucosal glands?
Which section of the small intestine contains abundant, very prominent GALT in the lamina propria?
Which section of the small intestine has no submucosal glands or very prominent GALT?
Duodenum (Brunner’s glands);
ileum (Peyer’s patches);
jejunum
What types of cell are found in the colon?
Abundant goblet cells;
colonocytes;
some enteroendocrine;
stem cells
What two locations in the gut have large, circular aggregations of GALT, often with germinal centers?
The ileum (Peyer’s patches);
the appendix
What type of epithelium covers the anal canal?
Keratinized stratified squamous epithelia
What section of the GI tract is this?
Jejunum
D.
(appendix)
While looking at a slide showing a section of the GI tract, you notice an abundance of lymphocytes.
What section of the tract is this?
Inconclusive information given
(80% of body lymphocytes are found in the GALT. More information needed.)
Which of the following does the large intestine not have:
Villi
Microvilli
Crypts
Villi
What are the three major salivary glands?
Parotid,
submandibular,
sublingual
Describe the following three salivary glands with respect to secretion (serous vs. mucous):
Parotid
Sublingual
Submandibular
Parotid - Serous
Sublingual - Mixed (majority mucous)
Submandibular - Mixed (majority serous)
From smallest to largest, what are the three stages of duct in salivary glands?
Intercalated –> Striated –> Interlobular
Describe the histological characteristics of the following three duct ‘levels’ of a salivary gland:
Intercalated
Striated
Interlobular
Intercalated - flattened cuboidal
Striated - eosinophilic; aligned basal mitochondria
Lobular - pseudostratified or simple columnar
Are any contractile cells present in salivary glands?
Myoepithelial cells
Are the myoepithelial cells of the salivary glands within or outside the basal lamina of the ductal cells?
Within
True/False.
The exocrine pancreas has myoepithelial cells around its acini.
False.
What are the three ‘stages’ of pancreatic duct segments from the acini to the main pancreatic duct?
Centroacinar cells –>
Intercalated ducts –>
Intralobular ducts
Describe the histological characteristics of the following three duct ‘levels’ of a given pancreatic exocrine gland:
Centroacinar
Intercalated
Intralobular
Centroacinar - pale, small
Intercalated - very short / simple cuboidal
Intralobular - simple cuboidal
True/False.
The gallbladder has no goblet cells.
True.
What type of necrosis is present in acute pancreatitis?
Fat necrosis
What is in the center of a liver lobule?
What are at the hexagonal corners?
A central vein;
the portal triad
What are the portions of the portal triads found in the liver?
Hepatic artery branch
Portal vein branch
Bile duct branch
What type of vessel is a liver sinusoid?
A discontinuous (sinusoidal) capillary
Where is the perisinusoidal space (space of Disse)?
Between the sinusoidal epithelium and the hepatocytes
What cellular structure in the space of Disse (perisinusoidal space) can be visualized via EM?
Hepatocyte microvilli
True/False.
The hepatic venous blood flow and bile flow within the portal triads is in the same direction, towards the central vein.
False.
The hepatic venous blood flow and bile flow within the portal triads are in opposite directions, venous blood towards the central vein and bile flow away.
What immune cell is found in the endothelial lining of the hepatic sinusoids?
Kupffer cells
What myofibroblast precursor is found in the perisinusoidal space (of Disse)?
What substance does it store?
Ito cells;
vitamin A
______ cells are highly involved in the collagen deposition in liver fibrosis and/or portal hypertension.
Ito (stellate)
What epithelium lines the gallbladder lumen?
Simple columnar
(tallest in the body)
What are the two roles of the gallbladder?
Store bile;
concentrate bile (reabsorb water)
Glisson’s capsule surrounds the ________.
Liver
What two substances are often found in hepatocyte granules?
(Hint: one is a storage unit; one is a sign of wear-and-tear.)
Glycogen;
lipofuscin
Bile ductal cells have ______________________ epithelia.
Simple cuboidal
What are the three zones of a hepatic acinus?
Zone 1 - close to lobule artery
Zone 2 - in the middle
Zone 3 - close to central vein
What is the importance of the three hepatic zones in regards to oxygenation?
Zone 1 - most oxygenated
Zone 2
Zone 3 - least oxygenated
What is the importance of the three hepatic zones in regards to metabolism?
Zone 1 - primary site of gluconeogenesis
Zone 2
Zone 3 - primary site of detoxification / glycolysis
Which zone of the liver has the lowest oxygenation?
Zone 3
Which zone of the liver is the primary source of gluconeogenesis?
Zone 1
Which zone of the liver is the primary source of detoxification?
Zone 3
Which zone of the liver is the primary source of glycolysis?
Zone 3
C.
A.
What are the two ducts on the left?
What is the duct on the right?
Striated;
intercalated
(parotid gland)
D.
(smaller than size of acinus; low cuboidal)
D.
(Interlobar would be wayyy bigger)
Describe the general cellular structure of a salivary gland.
Describe the order of duct types.
Describe mucinous and serous acini.
What layer of cells surrounds mucous cells in a salivary gland mucous acinus?
A serous demilunes
Describe the biliary/pancreatic duct and sphincter system anatomy.
Describe pancreatic acinar cells according to their apical and basolateral sides.
Pyramid shaped;
apical - zymogen granules
basolateral - RER
Describe the general structure of a pancreatic acinus.
Describe the structure of a pancreatic duct leading off an acinus (in terms of unique cells found in the acinus and duct).
Which of the following does not have a striated duct?
Parotid glands
Pancreatic glands
Pancreatic glands
D. (pancreatic islets)
What part of a hepatic lobule provides the venous drainage to the lobule?
The central vein
(not the portal veins branches on the hexagonal points)
True/False.
Hepatocytes have microvilli on their apical surfaces and bile canaliculi on their basolateral surfaces.
False.
Hepatocytes have microvilli on their basolateral surfaces and bile canaliculi on their apical surfaces.
True/False.
Hepatocytes have cilia on their basolateral surfaces (in the perisinusoidal space of Disse).
False.
Hepatocytes have microvilli on their basolateral surfaces (in the perisinusoidal space of Disse).
What histological layer is present in most of the GI tract but not in the gallbladder?
The muscularis mucosae
Does the gallbladder have microvilli?
Yes.
What organ is this slide taken from?
Gallbladder
(note: tall simple columnar epithelia with microvilli, no clear muscularis mucosae)
B.
D.
D.
B.
Describe the three zones of hepatic lobules based on oxygenation.
Describe the three zones of hepatic lobules based on oxygenation levels.
What structure is shown here?
The gastro-esophageal junction
What is wrong with this esophagus?
Metaplasia (Barrett’s esophagus)
What are two different names for the vitamin A-storing fibroblast precursors found in the perisinusoidal space (of Disse) in the liver?
Ito cells
(stellate cells)
Name the most common locations for peptic ulcers according to decreasing frequency.
Duodenum –>
gastric antrum –>
within Barrett’s esophagus –>
margins of prior gastric surgery
What percentage of peptic ulcers have bleeding as a complication?
30%
Are peptic ulcers usually multiple or solitary?
What size are they normally?
Solitary;
< 4 cm
___% of GI polyps are non-neoplastic.
90
__% of gastric malignancies are gastric carcinomas.
90
What is the 5-year survival rate for gastric carcinoma?
10%
What are two major forms of inflammatory bowel disease?
Crohn’s disease;
ulcerative colitis
What is a potential cause for inflammatory bowel disease?
Post-viral autoimmune attack
(mimicry - maybe some specific body proteins look like the viral proteins)
Describe the lesions of Crohn’s disease.
Intermittent (‘skip’) lesions; strictures; linear ulcers; fissures/perforations
Describe the lesions of ulcerative colitis.
Extends continuously from rectum in proximal direction
What layers are involved in Crohn’s disease.
Are granulomas present?
Transmural;
yes (noncaseating)
What layers are involved in ulcerative colitis.
Are granulomas present?
Mucosa (sometimes submucosa);
no
