associated glands of GI tract histology 2006

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what's the range in size of glands of intestine?: from single-celled to entire organ like pancreas
where are the associated glands of the GI tract?: all over the place
what do the associated glands of the GI tract typically secrete?: nothing general can be said about them, they differ
what are the salivary glands?: 3 of them
1. parotid
2. submandibular
3. sublingual
what subdivisions is the pancreas broken up into?: exocrine pancreas
endocrine pancreas
what are the main cells of the liver?: hepatocytes
what do hepatocytes do?: 1. make bile
2. control carb reserves
3. metabolize blood lipids
4. make plasma proteins
what are important structures to know in the liver?: 1. Space of Disse
2. bile canaliculus
what vasculature is important to know about in liver?: 1. hepatic artery and portal vein
2. hepatic vein
3. bile canaliculi
4. lymphatics
5. liver lobule
what is an example of fat cells in the liver and what do they do besides store fat?: example: perisinusoidal
function: vitamin A storage as well as fat
what's important to know about Kupfer cells - where are they, what do they do?: location: intrasinusoidal
function:
1. monitor intestinal pathogens
2. make bile
what kind of tissue makes up the mucosa of the gall bladder?: simple columnar epithelium, like entire GI tract except for very beginning and very end
how many salivary glands are there?: there are NOT 3!
there are much more than 3, but there are only 3 huge ones
there are a lot of minor unnamed salivary glands in submucosa of oral cavity
where are most salivary glands?: in submucosa of oral cavity
what's a clinical correlate of the salivary glands?: can get occluded
this results in small fluid-filled cyst in oral mucosa
when do the three major salivary glands secrete saliva?: when stimulated by food, either in mouth, or aroma of
what are a set of named glands in oral cavity i should know besides salivary?: serous glands of Von Ebner in tongue
where are the serous glands of Von Ebner?: in tongue
what are the glands in the tongue called?: serous glands of Von Ebner
how much saliva is made per day?: about 1.2 liters
what's Sjogren's syndrome?: is failure in both salivary glands and lacrimal glands that result in dry mouth and dry eye
what's the name of the syndrome with symptoms of dry mouth and dry eye?: Sjogren's syndrome
what causes Sjogren's syndrome?: failure of salivary glands and lacrimal glands
what are the functions of saliva?: 1. moisten food
2. adds lysozyme to mouth to keep oral bacteria under control
3. starts carb digestion with alpha amylase - also adds to lubrication
4. secretes IgA that neutralizes pathogens
5. secretes bicarbonate - this buffers things for esophagus to prevent any damage from stomach acid that might bubble up
could also help preserve enamel integrity as well
what does lysozyme do?: is bacteriolytic enzyme
what enzyme in the saliva helps digest carbohydrates?: alpha amylase
what's the point of having bicarbonate in our saliva?: helps reduce wear on esophagus of stomach acid
reduces damage to teeth enamel from stomach acid?
what cells are dominant in the secretory acini and intercalated ducts of salivary glands?: myoepithelial
what cells are one of teh most common causes of parotid tumors?: myoepithelial
where are myoepithelial cells in salivary glands?: in secretory acini and intercalated ducts
what do intercalated ducts secrete and what are they ducts of?: secrete bicarbs and Cl-
are ducts of salivary glands
what do striated ducts secrete and what are they ducts of?: secrete K, IgA, lysozyme
RESORB sodium - resorb more sodium than secrete K
ducts are in salivary glands
what's the result of striated ducts absorbing more sodium than secreting K?: hypotonic saliva
what are the different kinds of ducts in the salivary glands?: intercalated and striated
what are all the salivary glands apparently divided into to make histological study easier?: parenchyma and stroma
what is parenchyma?: whatever tissue in organ that's NOT connective tissue, functional tissue
what's stroma?: is supporting framework of an organ; usually is connective tissue
is opposite of parenchyma
what are the parts of the parotid gland's parenchyma that i should know about?: 1. acini - mostly serous
2. ducts - intercalated and striated both common
what should i know about the stroma of the parotid glands?: fat cells are common
considered characteristic feature of parotid stroma
what does the word acini refer to and how is it pronounced?: is small sac-like dilation of compound gland
pronounced ass-uh'-neye
what are the different kinds of acini that a gland could have?: could have serous, mucous or mixed serous demilunes
what are the acini like in the submandibular gland?: 80% serous, some serous demilunes
what does it mean that the acini in the parotid glands are mostly serous?: that means they secrete a watery substance as opposed to a goupy one
what's notable about teh ducts in the submandibular glands - what kind are they?: are intercalated, short, less frequent in section
what's the stroma like of the submandibular glands?: not different from "generic" gland
what kind of acini do the sublingual glands have?: mostly mucous acini, some serous demilunes present
what's the stroma of the sublingual glands like?: generic gland
where does mucous of saliva come from - which gland/s, and where does watery stuff come from, which gland/s?: parotid only puts out watery stuff
submandibular mostly puts out watery stuff with very little mucous
sublingual is where the mucous is at
what kind of ducts make up the majority of the pancreas - exocrine or endocrine?: exocrine
what's the approximate volume of digestive enzymes and fluids contributed to the intestine daily from the pancreas?: 1.2 liters
what constitutes the endocrine component of the pancreas?: islets of langerhans
what are the islets of langerhans?: are small islands of cells scattered throughout pancreas
what part of the pancreas is most affected by pancreatitis?: head
why are patients with pancreatitis still able to control carbohydrate metabolism?: still have islets in body and tail of pancreas
build an exocrine pancreatic acini. what kind of cells are there, in what structure?: about 40-50 pyrimidal cells around small central lumen
what organelles are significant to note in pyrimidal cells of exocrine acini in pancreas?: 1. zymogen granules which are apically oriented = secretory granules
2. supranuclear golgi
3. central-basal nucleus
4. basal ER
secretory granules, golgi, nucleus, ER
how does the pancreas protect itself from self digestion if its secreting digestive enzymes into intestine?: doesn't secrete active enzymes
secretes enzyme precursors that are only activated when reach intestinal lumen
what's an example of an intestinal enzyme that cleaves trypsinogen to trypsin?: enterokinase
what does trypsin do?: trypsin doesn't actually digest anything itself; it just activates digestive enzymes
has to be activated itself though by enterokinase - activator needs an activator
what hormones is released by intestinal enteroendcrine cells that act on pancreas?: CCK - cholescystokinin
what does CCK do to pancreas?: stimulates acinar cells to secrete
what do myoepithelial cells in pancreas do?: nothing; there are no myoepithelial cells in pancreas
what's a unique feature of pancreatic exocrine ducts?: initial segment pushed well into acinus
why are cells in pancreatic exocrine acinus called centroacinar cells?: because they look like they're in the center of the acinus instead of at periphery
what kinds of cells - what shape are the cells of the pancreatic exocrine acinus?: low cuboidal to squamous
what does it mean to say that the centroacinar cells are continuous with the intercalated duct?: i have no idea what that means
what do the intercalated ducts in the pancreas secrete?: 1. bicarbonate
2. water
why do intercalated ducts of pancreas secrete bicarbonate?: this is to neutralize acid from stomach
this is absolutely crucial
what's another secretion of the enteroendocrine cells besides CCK?: secretin
what does secretin do?: secretin stimulates intercalated ducts of pancreas
would there be endocrine ducts of pancreas?: no; words endocrine and duct are opposites - if see word duct, know that they're referring to exocrine function
what do the striated ducts of the pancreas secrete?: nothing, there are no striated ducts in the pancreas
what is the duct of Wirsung, where is it, what does it look like, what does it do?: is THE duct of pancreas that all other intercalated ducts dump into
empties into duodenum at papilla of vater
what's the name of the major duct of the pancreas that all intercalated ducts join to form?: duct of Wirsung
where does the duct of wirsung dump its stuff into duodenum?: papilla of vater
what's the shape, layering of epithelia of duct of wirsung?: is stratified cuboidal/columnar epithelium
this is rare
where could one find the rare organization of stratified cuboidal/columnar epithelium?: in duct of wirsung in pancreas
what starts and stops pancreatic secretions?: nothing, it's constantly secreting
secretes MORE when hormones are stimulated by presence of food, which then stimulate ducts/cells
what stimulates enteroendocrine cells to release CCK and secretin?: 1. distension of stomach
2. introduction of acid into duodenum
what do CCK and secretin stimulate pancreas to do?: CCK = stimulates acinar cells which secrete digestive enzyme precursors (zymogen granules sitting at surface)
secretin = stimulates intercalated ducts which release bicarbonate and water
what are some of the functions of the liver?: there are many
1. is exocrine organ
2. secretes bile
3. processing incoming nutrients from intestine
4. makes and secretes many protein components of blood
5. helps with carb metabolism and storage
6. official detox center - fishing out and neutralizing many of digested nasties
when is bile secretion from the liver stimulated?: always; hepatocytes are always making bile
it's the gall bladder's job to store, concentrate and control the release of bile
what artery does the hepatic artery come off of?: branch off abdominal aorta!!
what are the characteristics of hepatic portal vein blood in terms of oxygen and nutrient content? contrast this with supply of blood from hepatic artery: is oxygen poor, but nutrient rich
hepatic artery is oxygen rich but nutrient poor
what cells make up the liver?: 1. mostly hepatocytes
2. Ito cells or perisinusoidal fat cells
3. kupfer cells aren't officially considered part of liver parenchyma, but are in liver sinusoids
what kinds of cells are kupfer cells?: are macrophages
what the hell are Ito cells and where are they?: are in liver and are perisinusoidal fat cells
what are the different kinds of acini in the liver?: there aren't any acini in liver
liver is organized according to lobules
what makes up a liver lobule?: have vein in center of spokes or plates of hepatocytes
what shape does a liver plate take on in cross section?: hexagonal
how big are liver hepatocytic plates?: 0.3 mm by 2 mm
is the distance between plates evenly distributed throughout the liver lobules? if not, why not?: no; there's more space between the plates the further from the central vein you go
this is to allow room for more plates to develop
what part of the liver looks hexagonal in cross section?: LOBULES not plates
what's a portal tract, where is it and what's in it?: is collection of vessels and connective tissue between liver lobules
contains:
1. incoming blood - arteriole from hepatic a.
2. vein = from portal vein
3. lymph
4. duct for bile to leave
what's another name for portal tracts in the liver?: portal triads
what makes up the portal triads of the liver?: same as portal tracts
vessels and connective tissue
1. arteriole from hepatic a.
2. vein from portal v.
3. lymph
4. duct for bile that's leaving
in what direction do the vessels of the portal tract run?: parallel to the central vein; longitudinally
what are terminal portal venules?: these are horizontal arteriolar and venous branches between stacked liver lobules
where do the hepatic artery and portal vein merge?: at hepatic sinusoid
at periphery of liver
do the central veins of the liver lobules take away blood from the hepatocytes or supply them?: take away - get blood from branches hepatic sinusoid which is where portal vein and hepatic artery merge
where are sinusoids in relation to hepatocyte plates?: are on either side of the plates of hepatocytes!
what structures and/or lack of structures help promote extensive exchange tween blood and hepatocytes in sinusoids of liver lobules?: 1. gaps tween cells
2. fenestrations through walls of individual endothelial cells
3. basal lamina is barely there when it rarely is
4. microvilli on apical surface of hepatocytes
what's the space between sinusoidal endothelium and hepatocyte called?: Space of Disse or Perisinusoidal Space
where is the Space of Disse or Perisinusoidal Space?: is space between sinusoidal endothelium and hepatocyte in liver
what does the central vein become and where does it eventually drain?: becomes hepatic vein that dumps into IVC
what's the liver acinus?: is alternative to organizing liver by lobules
would put incoming blood from portal tract = terminal portal venules at center of unit, central vein at periphery
what's advantage to organization of liver into acini instead of lobules?: distance from hepatocyte to hepatic artery more important to function of hepatocyte than distance to central vein
cells nearest terminal portal veins
actually, not necessarily more important to function, depends on what functions you're looking at, but definitely more important for pathology
what's the difference between hepatocytes nearest the terminal portal veins and those furthest away?: close = more active in gluconeogenesis
and oxidative metabolism
farthest = most active in glycolysis and lipid/drug metabolism
what's the major exocrine secretory product of the liver?: bile
what cell makes bile?: hepatocyte
how does bile get to gall bladder?: through bile duct of portal tract
how does bile get from hepatocyte to bile duct?: via tiny channels between cells called canaliculi
sealed off by adjoining tight junctions
where are the canaliculi of the hepatocytes?: equidistant from sinusoids which are on either side of plate of cells
parallel to sinusoids, halfway between
where do the canaliculi of the hepatocytes join up with the bile duct?: edge of plate near portal tract
compare the directions of bile and blood flow in relation to portal tract: bile flow toward portal tract, blood flows away
what are three major surfaces to know about hepatocytes?: 1. perisinusoidal surface
2. bile canalicular surface
3. lateral surface
where is the perisinusoidal surface of the hepatocyte?: is against Space of Disse
where is the bile canalicular surface of the hepatocyte?: faces bile canaliculus
where is lateral surface of hepatocyte?: faces other hepatocytes
are there hepatocytes that have two nuclei and if so, how common is that?: yes; 25% of hepatocytes are binucleate
what organelles characterize the hepatocyte?: rich in RER - makes lots of plasma proteins
SER - makes VLDL
golgi - near bile canalicular surface
glycogen - hepatocytes are major storage sites for glycogen
what's the half life of hepatocytes?: 150 days
is the liver capable of regenerating itself?: of course!
can remove 2/3rds of liver in some rodents and is replaced within DAYS
human liver not that fast
what happens if there is no bile in body?: can't absorb fat - is that a bad thing?
what's in bile?: 1. bile salts - made from cholesterol
2. bilirubin
3. IgA
what do bile salts do?: is major functional part of bile that allows it to emulsify fats in intestine
where does bilirubin come from?: is a product of hemoglobin degradation
what happens to bilirubin in hepatocytes?: is attached to glucuronide in ER, excreted into canaliculus
where does IgA come from again?: plasma cells of lamina propria in small intestine
what is Secretory Component?: is actually a specific structure, integral membrane protein made in liver
on hepatocyte membrane facing Space of Disse
what does Secretory Component do?: binds IgA from plasma
endocytocizes IgA, transports it to bile canaliculus
secretory component is then cleaved, leaving IgA in bile
how does IgA get into bile?: with a little help from Secretory Component, which is an integral membrane protein on hepatocytes that bind and transport IgA to canaliculi
what are VLDLs?: very low density lipoproteins
where do VLDLs come from and where do they go?: come from SER in hepatocytes from fatty acids that were assembled into triglyercides assembled into VLDLs
end up in Space of Disse by exocytosis
what significant plasma proteins does the liver make?: albumin, fibrinogen, thrombin, factor III - all needed to make blood clots
transthyretin, serum retinol binding protein
where are fat cells of Ito?: between sinusoidal endothelium and hepatocytes
what do fat cells of ito do?: store fat and vitamin A
what kind of collagen leads to scarring of liver and cirrhosis?: collagen type I and III
what cell helps increase accumulation of connective tissue that leads to cirrhosis of liver?: fat cell of ito
what are some problems caused by scarring of liver in cirrhosis?: venous circulation impeded
little diffusion tween endothelial cells and hepatocytes
where are the kupfer cells?: stretched out across sinusoids of liver
what do kupfer cells do?: because they're right in the blood stream of portal vein stuff they act to stop bacteria and pathogens that might have come through intestinal wall
what cells or structures have to take over some of the function of the spleen when the spleen is removed?: kupffer cells take over in RBC destruction
how does entrance of food into duodenum lead to bile released into duodenum?: enteroendocrine cells of small intestine detect food, secrete CCK
CCK enters blood stream, travels to gall bladder
smooth muscle cells contract releasing bile into duodenum
what causes gallstones?: inability to insolubilize cholesterol in gall bladder leads to gallstones
what is a complication of gallstone formation?: inflammation of gall bladder AND LIVER
what's another function of the gall bladder besides its storage and concentration of bile?: it also secretes excess amounts of water insoluble cholesterol
explain in broad terms the wall structure of the gall bladder: has mucosa - epithelium and lamin propria
single muscle layer
NO muscularis mucosa OR submucosa
what's the inside of the gall bladder look like?: kind of like stomach with folds that are meant to help with distention
what's the structure of cells in the mucosa of the gall bladder?: simple columnar
what's important to note about the epithelium of the gall bladder?: has brush border and therefore has absorptive function
what's notable about the lamina propria of the gall bladder - what would one expect from an organ that needs to move fluids out in large quantities (for concentration of bile)?: is highly vascularized
is there any kind of special organization i should know about the smooth muscle fibers in the muscularis layer of the gall bladder?: no; smooth muscle fibers run in all directions
esophagus: epithelial cells submucosa muscularis function: epithelial cells: stratified squamous, keratinocytes, langerhans cells
submucosa: sometimes glands
muscularis: both striated, mixed and smooth muscle
functions: conduction, lubrication
name epithelial cells, mucosal configurations, muscle types and function of layers of stomach: epithelial cells: simple columnar
surface mucous, neck mucous, parietal or oxyntic, chief, enteroendocrine cells
mucosal configurations: foveolae or pits with glands in them - pyloric, oxyntic or cardiac, are also rugae
muscularis: three layers of muscle in mixed directions
function: digestion
duodenum: epithelial cells, mucosal configuration, submucosa, function: epithelial cells: simple columnar, absorptive, goblet, paneth, enteroendocrine
mucosal configuration: villi, glands or crypts
submucosa: plicae circulare and mucosa, glands of Brunner
functions: digestion, absorption
jejunum and ileum epithelial cells mucosal configuration submucosa functions: epithelial cells: simple columnar, absorptive, goblet, paneth, enteroendocrine, M cells which are over Peyer's patches
mucosal configuration: villi and glands (crypts)
submucosa: plicae circulare (includes mucosa), Peyer's Patches
functions: digestion, absorption
large intestine: epithelial cells mucosal configuration functions: epithelial cells: simple columnar, absorptive, goblet increased, enteroendocrine
mucosal configurations: glands (crypts)
function: absorption, lubrication
appendix epithelial cells mucosal configuration submucosa function: epithelial cells: simple columnar, absorptive, more goblet
mucosal configurations: glands with crypts
submucosa: lymphoid domination
function: immune
what epithelial tissue type is common throughout the GI tract except the esophagus?: simple columnar
what cells begin to show up in duodenum and continue to exist all the way through large intestine?: absorptive and goblet cells
where in GI tract are paneth cells?: only in small intestine
where in GI tract are enteroendocrine cells?: everywhere except esophagus and appendix
which part of GI can chief cells be found?: only in stomach
where in GI tract are parietal cells?: only in stomach!
what cells only show up in the stomach and nowhere else in GI tract?: almost all the epithelial cells of the stomach are unique to the stomach except for enteroendocrine cells
surface, neck mucous, chief and parietal cells are all unique to stomach
where are M cells in GI tract?: just jejunum and ileum
are any cells of the esophagus found anywhere else in the GI tract?: no; they're all specialized
keratinocytes and langerhans cells are only in esophagus as far as GI tract is concerned
what the hell are mucosal configurations?: basically they're just referring either to glands or to bumps or pits
which part of the GI tract has mucosa with both villi and glands?: just small intestine, minus appendix
at which part of the GI tract are there only glands in the mucosa and no villi?: only in appendix and large intestine where absorption is not an issue
what special mucosal configurations are unique to the stomach?: foveolae or pits with glands galore - pyloric, oxyntic, cardiac
rugae
where in the GI tract would i expect to find plicae circulare?: just in small intestine - minus appendix of course
where in GI are peyer's patches?: just in jejunum and ileum
where in GI are glands of brunner: in duodenum
what's the only part of the GI that sometimes has glands in the submucosa?: esophagus
parotid gland: name the types of acini, acinar cells, ducts and non-exocrine features: acini: serous with occasional mucous
acinar cells: serous, myoepithelial
ducts: intercalated and striated
non-exocrine features: fat cells
submandibular glands: name types of acini, acinar cells, ducts and non-exocrine features: acini: serous 80%, mucous 20% and some serous demilunes
acinar cells: serous, mucous and myoepithelial
ducts: striated and few intercalated
non-exocrine features: none!
sublingual glands: acini, acinar cells, ducts and non-exocrine features: acini: mucous 80%, serous 20% and serous demilunes
acinar cells: serous, mucous, myoepithelial
ducts: striated and few intercalated
non-exocrine features: none!
pancreas: acini, acinar cells, ducts, non-exocrine features: acini: serous
acinar cells: serous, centroacinar
ducts: intercalated
non-exocrine features: islets of langerhans
which glands put out mucous?: submandibular and sublingual

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