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291 Cards in this Set
- Front
- Back
from what embryonic tissue is GI tract derived?
|
endoderm
|
|
what are the 4 concentric layers of the GI tract?
|
Mucosa
Submucosa Muscularis externa Serosa (adventitia) |
|
what are the three layers of the mucosa of the GI tract?
|
epithelium
lamina propia muscularis mucosa |
|
what lines the lumen of the digestive tract?
|
mucosal epithelium
|
|
what type of tissue makes up the mucosal epithelium of the GI tract?
|
simple columnar epithelium
or stratified squamous epithelium |
|
what makes up the lamina propia of the GI tract mucosa?
|
loose connective tissue
(part of diffuse lymphatic system) |
|
how many layers of smooth muscle are in the muscularis mucosa of the GI tract?
|
1-3
|
|
what is the function of the muscularis mucosa?
|
motility of mucosa
forces lymph from lacteal into lymphatic vessels (causes villi to contract and shorten) |
|
what type of epithelium lines the large intestine?
|
simple columnar
|
|
what composes the submucosa of the GI tract?
|
dense, irregular connective tissue
blood vessels lymphatic vessels submucosal nerve plexus |
|
what is present in the submucosa of only the esophagus and duodenum?
|
glands
|
|
what are the two layers of smooth muscle in the muscularis externa layer of the GI tract?
|
inner is circular
outer is longitudinal (stomach has third layer) |
|
what is the outer layer of muscularis externa called in the colon?
|
taenia coli
smooth muscles of muscularis externa gathered into 3 bands |
|
where in the GI tract is the muscularis externa composed of striated muscle?
|
upper esophagus
|
|
where is the myenteric (Auerbach's) nerve plexus?
|
between layers of muscularis externa
|
|
what is the function of the muscularis externa?
|
motility of gut wall
|
|
what controls peristalsis?
|
nerve stimulation
stretching of muscle paracrine hormones |
|
what is serosa in the external layer of the GI tract?
|
mesothelium (simple epithelium) over a layer of loose connective tissue
|
|
what is adventitia in the external layer of the GI tract?
|
connective tissue layer
|
|
how does the esophagus move food to the stomach?
|
peristaltic activity of muscularis externa
|
|
what type of epithelium lines the esophagus?
|
non-keratinized stratified squamous epithelium
|
|
how many layers of smooth muscle are contained in the muscularis mucosae of the esophagus?
|
one
|
|
what are the two sets of esophageal glands?
|
esophageal glands proper
esophageal cardiac glands |
|
wha is secreted by both sets of esophageal glands?
|
mucus
|
|
where are the esophageal glands proper?
|
scattered along the length of the esophagus
in submucosa |
|
what is the purpose of the esophageal glands proper?
|
lubricate the lumen of the esophagus
|
|
where are the esophageal cardiac glands?
|
near cardiac portion of stomach
in lamina propia of esophagus |
|
what is the purpose of the esophageal cardiac glands?
|
protect esophagus from gastric reflux
|
|
what is contained in the muscularis externa of the esophagus?
|
skeletal muscle in upper third
combination of skeletal and smooth muscle in middle third smooth muscle in lower third |
|
what is another name for Barrett's esophagus?
|
gastroesophageal reflux disease (GERD)
|
|
what is an early symptom of Barrett's esophagus?
|
heartburn
|
|
what is known as Barrett's esophagus?
|
metaplasic changes of the esophageal lining due to chronic acid reflux
|
|
what does an esophagus with GERD resemble histologically?
|
simple columnar epithelium of small intestine
(has abundant goblet cells to protect lining from stomach acid) |
|
what disorder is prevalent in patients with Barrett's esophagus? (what are they at increased risk of developing?)
|
esophageal adenocarcinoma
|
|
what are the two physiologic sphincters of the gastroesophageal junction?
|
pharyngoesophageal
gastroesophageal |
|
what is the purpose of the two physiologic sphincters?
|
prevent reflex of gastric contents
|
|
how are physiologic sphincters different from anatomical sphincters?
|
physiologic sphincters - no thickening of muscle layers
anatomical sphincters - thickening of muscle layers |
|
what causes the closure of the lumen in physiologic sphincters?
|
nerve innervation
|
|
what acidifies and converts food from esophagus into a thick, viscous fluid called chyme?
|
stomach
|
|
what are the three histologically distinct regions of the stomach?
|
cardia
fundus (body) pylorus |
|
what is the name for longitudinal folds in the mucosa and submucosa of the stomach? when do they disappear?
|
rugae
disappear with stomach distention |
|
what are the three layers of smooth muscle in the muscularis externa of the stomach?
|
oblique
circular longitudinal |
|
what type of epithelium lines the stomach?
|
simple columnar epithelium
|
|
what is the name for epithelial invaginations of the stomach?
|
gastric pits
|
|
where do gastric pits extend?
|
into lamina propia
|
|
what is the purpose of the gastric pits of the stomach?
|
serve as ducts for the branched, tubular gastric glands
|
|
how many layers of smooth muscle are in the muscularis mucosae of the stomach?
|
2-3 layers
|
|
where are surface mucous cells?
|
lining the gastric pits of the stomach
|
|
what do surface mucous cells secrete?
|
alkaline mucus to coat the stomach lumen
|
|
what is the purpose of the mucus secreted by the surface mucus cells in the stomach?
|
protects epithelial surface from acid and abrasion
|
|
how do surface mucous cells stain?
|
darkly
|
|
where are mucous neck cells located?
|
in the neck of the gastric glands
|
|
what is secreted by the mucous neck cells?
|
acidic mucous
(unlike alkaline mucous of surface mucous cells) |
|
where are undifferentiated stem cells found in the stomach?
|
in the neck of gastric glands
|
|
where does cell division occur in the stomach?
|
in the neck of gastric glands
where there are undifferentiated stem cells |
|
what is another name for parietal cells of the stomach?
|
oxyntic cells
|
|
in PAS/alcian blue stain, what color do surface mucous cells stain? mucous neck cells?
|
dark purple
medium purple |
|
what are parietal cells of the stomach?
|
large eosinophilic cells with round, centrally placed nucleus
|
|
where are parietal cells of the stomach most numerous?
|
neck and body of gastric glands
|
|
what is secreted by parietal cells of the stomach?
|
HCl
Intrinsic factor |
|
what is the purpose of HCl secreted by gastric parietal cells?
|
promotes hydrolysis of food substrates
acidic environment converts pepsinogen to pepsin |
|
what is the purpose of intrinsic factor?
|
complexes with vitamin B12, to facilitate its absorption in intestine
|
|
what is apparent in gastric parietal cells at EM level?
|
abundant mitochondria
abundant intracellular canaliculi |
|
what happens within gastric parietal cells when they are stimulated?
|
tubulovesicles in the apical cytoplasm fuse to form intracellular canaliculi which empty into the lumen of the gland and increase surface area for HCl secretion
|
|
what stimulates the production of HCl in gastric parietal cells?
|
hormones (e.g. gastrin)
cholinergic nerve endings |
|
what is released by gastric parietal cells as a byproduct of HCl production?
|
bicarbonate
|
|
what causes an increase of blood pH following meals?
|
absorption by blood of bicarbonate (produced by gastric parietal cells as byproduct of HCl production)
|
|
where are chief cells located?
|
base of gastric glands
|
|
how do chief cells appear when stained?
|
basophilic with abundant RER
|
|
what is secreted by chief cells?
|
pepsinogen
|
|
what is pepsinogen?
|
inactive precursor for pepsin, a proteolytic enzyme
|
|
where do enteroendocrine cells mainly occur?
|
in the base of gastric glands
|
|
what are enteroendocrine cells?
|
small cells with many small secretory granules found throughout GI tract
"clear" cells in H&E stained sections |
|
what is secreted by enteroendocrine cells?
|
endocrine hormones
paracrine hormones (serotonin, gastrin) |
|
what structures are in the cardia of the stomach?
|
shallow pits
|
|
what is mainly secreted by the glands in the cardia of the stomach?
|
mucus
lysozyme |
|
what structures are in the fundus of the stomach?
|
shallow pits
long glands |
|
what cells are abundant in the fundus of the stomach?
|
parietal cells
chief cells |
|
what hormones are secreted by fundus portion of stomach?
|
serotonin
glucagon |
|
what hormones are secreted by pylorus portion of stomach?
|
gastrine
|
|
what structures are found in the pylorus region of the stomach?
|
deep pits
short glands |
|
what type of cells predominate pylorus region of the stomach?
|
mucus cells
|
|
what bacteria is strongly associated with peptic ulcers, chronic gastritis, duodenitis, and stomach cancer?
|
helicobacter pylori
|
|
where do most peptic ulcers occur?
|
duodenum
|
|
what causes mucosa to become eroded away in the center of ulcers?
|
inflammation
necrosis |
|
what is a common system of gastric ulcers?
|
vomiting with blood
|
|
what examination is performed on patients who vomit blood?
|
gastroscopy
|
|
what is ordered for gastric ulcers as the result of a small percentage of them being cancerous?
|
biopsy
|
|
what is used in cytopathology of an ulcer?
|
tiny nylong brush scraped over ulcer, collecting cells for analysis
|
|
what is the distinguishing feature of the duodenum?
|
Brunner's glands
|
|
what is the purpose of the small intestine?
|
hydrolyze food particles
absorb via epithelium then transferring them to blood and lymphatic capillaries in lamina propia |
|
what are the three luminal surface modifications of the small intestine, designed to enhance absorption?
|
plicae circulares (valves of Kerckring)
villi microvilli |
|
what are plicae circulares?
|
valves of Kerckring
permanent spiral folds of submucosa and mucosa |
|
how much do plicae circulares increase surface area of the lumen of the small intestine?
|
3-fold
|
|
what are villi?
|
epithelium-covered finger-like projections of mucosa into the lumen
|
|
how much do the villi increase the surface area of the lumen of the small intestine?
|
ten-fold
|
|
what does the lamina propia core of villi consist of?
|
loose connective tissue
|
|
what is contained in villi?
|
central, blind-ending lymphatic capillary (lacteal)
|
|
where do smooth muscle fibers run in villi?
|
lengthwise in villus core
|
|
what are microvilli?
|
membrane specializations of the intestinal absorptive cells
|
|
how much do microvilli increase the surface area of the lumen of the small intestine?
|
20-fold
|
|
what are the two cell types in simple columnar epithelium of intestinal villi?
|
enterocytes
goblet cells |
|
what are enterocytes?
|
intestinal absorptive cells
primary absorptive cells of the small intestine tall, columnar cells with dense layer of microvilli |
|
what binds the enterocytes of the small intestine?
|
tight junctions
zonula adherens |
|
what are goblet cells?
|
unicellular glands that secret mucus
|
|
what is the purpose of goblet cells in the intestinal lining?
|
to protect intestinal lining from pancreatic enzymes and bacteria
|
|
what is contained in the apex of goblet cells?
|
numerous mucinogen granules
|
|
where is the number of goblet cells increased?
|
ileum, from that of duodenum
|
|
what is the other name for intestinal glands?
|
crypts of Lieberkuhn
|
|
what are intestinal glands composed of?
|
goblet cells
columnar cells enteroendocrine cells stem cells Panteh cells |
|
where are Paneth cells located?
|
at base of crypts in the small intestine
|
|
what are Paneth cells?
|
large cells with many apical, acidophilic secretory granules
|
|
what is secreted by Paneth cells?
|
lysozyme
(antibacterial enzyme) |
|
what is secreted by enteroendocrine cells?
|
various hormones
(GIP, secretin, CCK) |
|
what does GIP do?
|
inhibits gastric HCl secretion
|
|
what does secretin do?
|
stimulates bicarb secretion by pancreas
|
|
what does CCK do?
|
stimulates the release of pancreatic enzymes and gallbladder contraction
|
|
where are the small secretory granules of enteroendocrine cells located?
|
in the base of the cells
|
|
where are stem cells located in the small intestine?
|
in intestinal glands
|
|
what is the purpose of the intestinal stem cells?
|
divide to replace themselves and all intestinal epithelial cells
|
|
what are the common characteristics of lymphoid nodules in the duodenum and jejunum?
|
small
solitary |
|
what are the common characteristics of lymphoid nodules in the ileum?
|
increased in number from duodenum and jejunum
in large aggregates which extend through muscularis mucosae into submucosae |
|
what are Peyer's patches?
|
large aggregates of lymphoid nodules in the ileum
|
|
what do lymphoid nodules of the small intestine consist of?
|
M cells
B lymphocytes plasma cells |
|
what are M (microfold) cells?
|
flat epithelial cells overlying lymphoid nodules
antigen presenting cells |
|
what is present on the apical surface of M cells, rather than microvilli?
|
small folds
|
|
what happens after antigens are presented to B cells in the intestinal lumen?
|
form more B cells
enter lymph enter blood travel to lamina propia differentiate into plasma cells produce IgA IgA is transported across cytoplasm of enterocytes IgA neutralizes bacteria and antigents in intestinal lumen |
|
what is contained in the duodenum?
|
brunner's glands in submucosa
few goblet cells |
|
what is the purpose of Brunner's cells in the duodenum?
|
produce alkaline mucus
creates optimal pH for pancreatic enzyme activity protects intestinal epithelium from acid |
|
what is contained in the jejunum?
|
plica circulares
intermediate number of goblet cells no Brunner's glands no Peyer's patches |
|
what is contained in the ileum?
|
abundant goblet cells
many lymphoid nodules or Peyer's patches |
|
what enzymes hydrolyze carbohydrates to disaccharides?
|
salivary amylase
pancreatic amylase |
|
what cleaves disaccharides to monosaccharides?
|
disaccharides in glycocalyx of small intestine
|
|
how are monosaccharides absorbed?
|
actively transported into enterocytes
discharged into lamina propia enter blood vessels |
|
what protein in the stomach partially hydrolyzes proteins?
|
pepsin
|
|
what finishes hydrolyzing proteins into small peptides and amino acids?
|
pancreatic proteases
|
|
how are proteins absorbed?
|
actively transported into enterocytes
further degraded discharged into lamina propia taken up into blood vessels |
|
what degrades fats into monoglycerides, free fatty acids, and glycerol?
|
pancreatic lipases
bile acids |
|
what substances, derived from fats, are absorbed by enterocytes?
|
monoglycerides
free fatty acids glycerol |
|
where are triglycerides resynthesized and coated with lipoprotein?
|
smooth endoplasmic reticulum of enterocytes
|
|
what do triglycerides become when coated with lipoprotein?
|
chylomicrons
|
|
what happens to chylomicrons from enterocytes?
|
released into lamina propia
taken up by lacteals |
|
what are the alternative names for gluten enteropathy?
|
nontropical sprue
celiac disease |
|
what is gluten enteropathy?
|
autoimmune disorder of small intestine, caused by reaction to gliadin
|
|
what is gliadin?
|
a gluten protein found in wheat and rye
|
|
what happens histologically in gluten enteropathy?
|
shortening of intestinal villi
decreased absorption of nutrients |
|
what are the first presentations of gluten enteropathy?
|
folic acid deficiency
vitamin B12 deficiency vitamin K deficiency vitamin D deficiency |
|
what can a patient with gluten enteropathy do to return the villus morphology to normal over several months?
|
eat a gluten-free diet
|
|
what is crypt hyperplasia?
|
complete flattening of the mucosal surface of the intestine
|
|
what are the parts of the large intestine?
|
cecum
appendix colon rectum |
|
what is the function of the large intestine?
|
convert undigested food into feces by removing water and adding mucus
|
|
how is the muscularis externa arranged in the large intestine?
|
discontinuous, gathered into 3 bands (called teniae coli)
|
|
what is the only part of the large intestine with permanent folds (plicae)?
|
rectum
|
|
how many villi are in the large intestine? glands? lymphoid nodules?
|
no villi
numerous glands some lymphoid nodules |
|
are there lymphatic vessels in the lamina propia of the large intestine?
|
no
|
|
what type of epithelium lines the large intestine?
|
simple columnar epithelium
|
|
how many goblet cells are in the large intestine?
|
numerous
|
|
describe the absorptive cells of the large intestine.
|
short, irregular microvilli
|
|
how many enteroendocrine cells are in the large intestine?
|
occasional
|
|
where is a collagen table contained in the GI tract?
|
large intestine
|
|
what is the collagen table?
|
thick layer of collagen and proteoglycans adjacent to the basal lamina of the epithelium of the large intestine
|
|
what is the function of the collagen table?
|
participates in water and electrolyte transport
|
|
what do the cecum and appendix histologically resemble?
|
colon
|
|
what is the cecum?
|
blind pouch distal to the ileocecal valve
|
|
what is the appendix?
|
thin, fingerlike extension of cecum with numerous lymphoid nodules and no teniae coli
|
|
what is acute appendicitis?
|
an inflammation of the appendix, and a medical emergency
|
|
what are the main causes of mortality in appendicitis patients?
|
peritonitis
shock |
|
what can cause a primary obstruction of the appendix leading to appendicitis?
|
fecaliths
intestinal worms trauma lymphadenitis foreign bodies |
|
what are the surgical procedures to treat appendicitis?
|
removal via laparoscopic procedure
open laparotomy in cases with rupture or abscess |
|
what type of epithelium lines the anal canal?
|
simple columnar epithelium in top half
stratified squamous epithelium in bottom half |
|
what is located in the submucosa of the anal canal?
|
hemorrhoidal venous plexus
many sebaceous glands large apocrine sweat glands |
|
what are the other names for the apocrine sweat glands of the anal canal?
|
circumanal glands
scent glands |
|
what forms the internal anal sphincter? what type of muscle is this?
|
muscularis externa of anal canal
involuntary muscle |
|
what is the exocrine function of the pancreas?
|
secrete enzyme-rich fluid for digestion of dietary fats, carbohydrates, and proteins
|
|
what is the endocrine function of the pancreas?
|
secrete hormones that control carbohydrate metabolism
|
|
where does the endocrine function of the pancreas take place?
|
islets of Langerhans
|
|
what subdivides the gland into ill-defined lobules?
|
septa formed from the surrounding thin layer of connective tissue
|
|
what is contained within the septa of the pancreas?
|
blood vessels
lymph vessels interlobular ducts |
|
how is the pancreas classified?
|
serous, compound acinar gland
|
|
what does the pancreas resemble microscopically?
|
parotid gland
|
|
in what three ways does the pancreas differ from the parotid gland?
|
contains the islets of Langerhans
has centroacinar cells lacks striated ducts |
|
what are pancreatic acinar cells?
|
serous cells arranged around a central lumen, involved in exocrine function of pancreas
|
|
what is abundant in pancreatic acinar cells?
|
zymogen granules
rough endoplasmic reticulum |
|
what is secreated by the pancreatic acinar cells?
|
digestive enzymes
proenzymes (trypsinogen) |
|
what converts trypsinogen to trypsin?
|
enterokinase
|
|
where is trypsinogen converted to trypsin?
|
in the lumen of the small intestine
|
|
what cells secrete enterokinase? what is its function?
|
enterocytes
converts trypsinogen to trypsin |
|
what digestive enzymes are secreted by pancreatic acinar cells?
|
amylases
lipases ribonucleases deoxyribonucleases proteases (trypsin, chymotrypsin) |
|
where, in pancreatic acinar cells, are zymogen granules contained?
|
apical cytoplasm
|
|
in response to what are zymogen granules of the pancreatic acinar cells exocytosed?
|
cholecystokinin
parasympathetic innervation by vagus nerve |
|
what cells secrete cholecystokinin?
|
enteroendocrine cells of the small intestine
|
|
how do centroacinar cells appear?
|
flattened nucleus
pale-staining cytoplasm |
|
where are centroacinar cells located?
|
in the lumen of each pancreatic acinus, forming the intra-acinar portion of intercalated ducts
|
|
what is the path of pancreatic ducts?
|
intercalated ducts (beginning with centroacinar cells) -> intralobular ducts -> interlobular ducts -> main (or accessory) pancreatic duct
|
|
how are the intralobular ducts of the pancreas different from those in the salivary glands?
|
don't reabsorb any fluid from the lumen, therefore they have no striations in the cytoplasm
|
|
what is secreted by the cells in the intercalated ducts (including centroacinar cells) of the pancreas?
|
enzyme-poor alkaline fluid
|
|
what stimulates secretion by the intercalated duct cells in the pancreas?
|
secretin
|
|
what cells secrete secretin?
|
enteroendocine cells of small intestine
|
|
how do Islets of Langerhans appear?
|
pale-staining, spherical clusters of endocrine cells, scattered among acini of exocrine pancreas, with rich network of fenestrated capillaries
|
|
what constitutes 70% of islet cells?
|
beta cells
|
|
what is secreted by beta cells of the islets of Langerhans?
|
insulin
|
|
what constitutes 15-20% of cells in the islets of Langerhans?
|
alpha cells
|
|
what is secreted by alpha cells of the islets of Langerhans?
|
glucagon
|
|
what type of cells constitute 5-10% of islet cells?
|
delta cells
|
|
what is secreted by delta cells of the islets of Langerhans?
|
somatostatin
|
|
when is somatostatin secreted?
|
in response to increases of blood glucose, amino acids, and/or fatty acids
|
|
what is the function of somatostatin?
|
inhibits release of insulin and glucagon, and diminishes motility of the gut
slows uptake of nutrients from ingested food and to make products of assimilation available over longer period of time |
|
what possibly causes the destruction of pancreatic beta cells in type I diabetes?
|
viral infection
autoimmune disorder |
|
what happens to pancreatic beta cells in type II diabetes?
|
many islet cells are hyalinized
|
|
what does the term hyalinization mean?
|
deposition of amyloid
|
|
what are the four major functions of the liver?
|
exocrine secretion
endocrine secretion detoxification storage site |
|
what exocrine secretion is the liver responsible for?
|
bile
|
|
from what is bile synthesized?
|
waste products of erythrocyte destruction
|
|
where is bile secreted in the liver?
|
biliary tract
|
|
what is the endocrine secretion that the liver is responsible for?
|
plasma proteins (albumin, prothrombin, fibrinogen, lipoproteins)
urea |
|
what aspect of detoxification is the liver responsible for?
|
modifying potentially dangerous chemicals and drugs and rendering them harmless
|
|
for what does the liver serve as a storage site?
|
glucose
fats vitamin A |
|
what is the single type of parenchymal cell which composes the liver?
|
hepatocyte
|
|
how are hepatocytes organized?
|
plates of cells, with sinusoidal capillaries (sinusoids) located between them
|
|
what is the name for the thin capsule of connective tissue that covers the liver?
|
Glisson's capsule
(also divides liver into lobes and lobules) |
|
how many nuclei are contained in hepatocytes?
|
one, though some can be binucleate
|
|
what are the three ways of describing the liver, in terms of functional units?
|
classic lobule
portal lobule liver acinus |
|
how is a classic lobule described?
|
hexagonal mass of hepatic tissue drained by a central vein
|
|
what lines central veins?
|
endothelial cells
(no CT in vessel wall) |
|
what is located at the corners of a classic liver lobule?
|
portal canals
|
|
what is another name for portal canals in the liver?
|
triads
|
|
what three structures compose a portal canal?
|
branch of the portal vein
branch of the hepatic artery bile duct (also lymphatic vessels and connective tissue) |
|
what composes the dual blood supply of the liver?
|
portal vein
hepatic artery |
|
what are the three drainage systems of the liver?
|
hepatic veins
lymphatic vessels bile ducts |
|
where is blood from hepatic arterioles and portal venules received?
|
sinusoids between plates of hepatocytes
|
|
what type of blood is found in hepatic arterioles?
|
oxygen rich
|
|
what type of blood is found in portal venules?
|
nutrient-rich
|
|
where do sinusoids in the liver empty?
|
into central vein
|
|
where does the central vein form when it merges with other veins? where does this structure empty?
|
hepatic veins
inferior vena cava |
|
where do hepatic veins empty?
|
inferior vena cava
|
|
where is bile flow directed in the classic liver lobule?
|
towards periphery
(opposite direction as blood flow) |
|
what is the path of bile through the liver?
|
bile canaliculi -> bile ducts -> portal canals
|
|
what is the name of the small bile ductules which receive bile from bile canaliculi and empty into bile ducts of the portal canals?
|
canals of Hering
|
|
how is a portal lobule (of the liver) described?
|
triangular mass of hepatic tissue drained by a bile duct in a portal canal
|
|
what forms the corners of a portal lobule?
|
central veins
|
|
what is at the center of a portal lobule?
|
portal canal
|
|
what is emphasized by the portal lobule approach to the liver?
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exocrine function of the liver
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how is a liver acinus described?
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diamond-shaped region defined by blood flow into liver parenchyma
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how does a liver acinus relate to the classic liver lobules?
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formed by two triangular sections of adjacent liver lobules
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what defines the three zones into which each triangle of a liver acinus can be divided?
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distance from distributing blood vessels (branches of hepatic artery and portal vein)
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what explains the histologic appearance of pathologic changes in the liver?
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zones of the liver acinus
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why are hepatocytes in zone 1 of a liver acinus more susceptible to toxins?
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they receive first exposure to toxins, and absorb them
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why are hepatocytes in zone 3 of a liver acinus more susceptible to oxygen deprivation?
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they receive a less oxygenated blood supply (hepatocytes from first two zones take up much of the oxygen from the blood)
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in which zone of a liver acinus would one expect to find ischemic necrosis in the liver biopsy specimen of an individual with congestive heart failure?
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zone 3
|
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what types of cells are in the liver?
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hepatocytes
Kupffer Cells fat-storing cells |
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what is possessed by hepatocytes?
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abundant rough ER
abundant smooth ER mitochondria lysosomes peroxisomes lipid droplets glycogen deposits euchromatic nuclei |
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as oxygen availability to hepatocytes decreases (more distal zones in liver acinus), what variations of structural, histochemical, and biochemical characteristics increase?
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key glycolysis enzymes
key fatty-acid-synthesizing enzymes |
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as oxygen availability to hepatocytes decreases (more distal zones in liver acinus), what variations of structural, histochemical, and biochemical characteristics decrease?
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extrahepatic hormones
key glucose-liberating enzymes key fatty-acid-oxidation enzymes |
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what connects adjacent hepatocytes?
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desmosomes
tight junctions |
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what forms a seal around bile canaliculi?
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tight junctions of hepatocytes
|
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what separates hepatocytes from endothelial cells of the sinusoids?
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space of Disse
|
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what is represented by the space of Disse?
|
beginning of lymphatic pathway in liver
(fluid flows toward lymphatic vessels in portal canals) |
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what structures of hepatocytes help them to absorb nutrients, oxygen, and toxins?
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microvilli
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what are Kupffer cells?
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resident macrophages of the liver
|
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where are Kupffer cells located?
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in hepatic sinusoids
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what are fat-storing cells in the liver?
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stellate cells in space of Disse which accumulate fat and store vitamin A
|
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where are fat-storing cells in the liver?
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in the space of Disse
|
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in what form do fat-storing cells store vitamin A?
|
retinyl esters
|
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what is contained in bile?
|
bile salts
cholesterol bilirubin lecithin electrolytes fatty acids |
|
what is the function of bile salts?
|
emulsify ingested fat, facilitating the absorption of fatty acids and monoglycerides
|
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how much bile is recycled?
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90%
|
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what is increased in a cirrhotic liver?
|
production of fibrocollagenous (scar) tissue
|
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what is cirrhosis of the liver?
|
slowly progressing disease, which destroys hepatocytes and distorts liver architecture
|
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what are the most common causes of cirrhosis of the liver?
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alcohol toxicity
viral infection autoimmune liver disease |
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what is the problem with regenerating hepatocytes in a cirrhotic liver?
|
form irregular nodules
have abnormal relationships with microvasculature |
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what is the function of the gall bladder?
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concentrates, stores, and releases bile
|
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what is included in the simple wall structure of the gallbladder?
|
epithelium
lamina propia muscularis serosa (adventitia) |
|
in response to what does the muscularis layer of the gallbladder contract?
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cholecystokinin
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what cells release cholecystokinin? in response to what?
|
enteroendocrine cells in small intestine
in response to dietary fat |
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what does the mucosa of the gallbladder consist of?
|
simple, columnar epithelium overlying lamina propia
|
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what is the name for diverticula of the mucosa of the gall bladder?
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Rokitansky-Aschoff sinuses
|
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what is a characteristic feature of the gallbladder?
|
Rokitansky-Aschoff sinuses
|
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in the gall bladder, what creates an osmotic gradient, drawing water out of bile?
|
sodium pumps in the basolateral membrane
|
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with what is acute cholecystitis offten associated?
|
gallstones in the neck of the gallbladder
|
|
what causes inflammation of the gallbladder wall?
|
obstruction of bile
|
|
with what symptoms will a patient present if they have acute cholecystitis?
|
pain
right upper quadrant tenderness leukocytosis |
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what hormone, produced in the stomach, stimulates gastric acid secretion?
|
gastrin
|
|
what hormone, produced in the stomach, stimulates GH secretion and appetite?
|
ghrelin
|
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what hormone, produced in the duodenum and jejunum, stimulates GB contraction, pancreatic enzyme secretion, pancreatic bicarb secretion, and pancreatic growth, while inhibiting gastric emptying?
|
cholecystokinin
|
|
what hormone, produced in the duodenum and jejunum, stimulates insulin release which inhibiting gastric acid secretion?
|
gastric inhibitory peptide (GIP)
|
|
what hormone, produced by the duodenum and jejunum, stimulates gastric motility and intestinal motility?
|
Motilin
|
|
what hormone, produced by pancreas inhibits pancreatic enzyme secretion and pancreatic bicarb secretion?
|
pancreatic polypeptide
|
|
what hormone, produced by the ileum and the colon, inhibits gastric acid secretion, gastric emptying and food intake?
|
peptide YY
|
|
what hormone, produced by the ileum and colon, stimulates insulin release, while inhibiting gastric acid secretion and gastric emptying?
|
glucagon-like peptide 1 (GLP-1)
|
|
what hormone, produced by the stomach, stimulates gastric release?
|
Bombesin
|
|
what hormone, produced by mucosa and smooth muscle of the GI tract, stimulates pancreatic enzyme secretion and intestinal secretion, while inhibiting smooth muscle and sphincter contraction?
|
vasoactive inhibitory peptide (VIP)
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