Liver and Pancreas Flashcards
what are the major fuctions of the liver?
- Detoxification of metabolic waste
- Metabolism & detoxification of drugs & toxins
- Destruction of senescent RBC’s
- Recycling of Hb via synthesis & secretion of bile
- Synthesis of plasma proteins
- Miscellaneous metabolic functions
The liver demaiton of
Amino Acids to urea
Products of digestion enter the liver via
hepatic portal vein
the hepatic portal vein caries
- 75-80% of blood to the liver
- oxic compounds absorbed from diet
Oxygentated blood supplied to the live by
Hepatic Artery
The hepatic artery is a branch of the
celiac trunk
The hepatic artery carries only
20%-25 blood of the liver
mixes with unoxygenated from potal vein
Liver is a nutrient rich, but is
O2 poor environment
What is the order of venous drainage?
out of the liver
central vein –> hepatic vein
–> IVC
What is the main funcitonal cell of the liver
Hepatocytes
Hepatocytes are arranged in
plates or cords
around sinusoids
In the liver Endothelial cells line the
sinusoids
What ar the liver specific macrophages?
Kupffer cells
What cells store vitamin A & D in the liver
Stellate cells (Ito cells)
major for A
What are liver cells called
hepatocytes
hepatocytes shape
- polyhedral
- round nucleus
displaced chromatin - prominent nucleolus
Most hepatocytes _______,
but some are _____
diploid; polyploid &/or
binucleate
What are within the cytoplasmic granules of hepatocytes
rER
& lysosomal products
What do Aging hepatocytes
accumulate?
brown
pigment, lipofuscin
individual hepatocytes polygonal, arranged in
anastomosing cords paralleled by
Venous Sinusoids
Sinusoids lined by
sinusoidal
lining cells
sinusoidal lining cells
a discontinuous
endothelium, with gaps
between endothelial cells
What supports the hepatic cords and sinusoids?
meshwork of
reticulin fibers (Type III
collagen)
The reticulin fibers that support the Hepatic cords & sinusoids are what type of collagen?
type 3
What blackens the cytoplasm of kupffer cells?
carbon particles
Kupffer cells can be recognized by
their oval
nuclei closely associated
with sinusoidal spaces.
What can be used to stain Kupffer cells
trypan blue
Kupffer cells removve
- foreign particles
they also work with the spleen to destroy old RBCs
What are other names for the Stellate cells
- Ito cell
- perisinusoidal cell
- lipocyte
If the liver is injuried what happens
- stellate cells become transitional
- become capable of collagen synthesising
What types of collagen can Stellate cells synthesize?
1
aslo 3 and 4 and laminin
Do blood and bile travel in the same direction?
NO
Hepatic SInusoids
- Thin
- discontinuous
- highly fenestrated
- endothelium
Do the hepatic sinusoids rest on a basement membrane?
NO
What seperates the hepatic sinusoids from the hepatocytes?
space of Disse or perisinusoidal space
Space of Disse
perisinusoidal space
- found in the liver
- between hepatocytes and sinsuoid
- contain blood plasma
What portion of the hepatocyte extends into the Space of Disse
microvilli
Microvilli of hepatocytes
allowing proteins and other plasma components from the sinusoids to be absorbed by the hepatocytes.
What is a low resistance vascular channel
hepatic sinusoids
what makes bile?
hepatocytes
where do hepatocytes secrete bile into?
bile canaliculi between cells
Blood flow in the liver
Hepatic vien/artery-(in triad)>
hepatic sinusoids->
central vein (then out of liver)
bile flow in liver
hepatocypes make->
bile canal->
bile duct
opposite if blood
Cords of hepatocytes are arranged in
lobules
Classic Lobule
* based on blood flow
* roughly hexagonal
* central vein in middle of lobule
what is at the center of the classic lobule?
centrilobular vein
What is the outer margin of each lobule?
connective
tissue septum
The central vein in middle of lobule can also be refered to as
- centrilobular vein
- terminal hepatic venule
Where do you find portal tracks?
triads
each coner of the classic lobule
The portal tract/triad contain
hepatic artery, portal
Vein & bile duct
lymphatics too?
Blood enters from portal tracts,
percolates through sinusoids of lobule,
drains via
central vein
Portal Lobule is
- triangular area
* based on bile flow
In a portal lobule has a portal triad ______ and central vein ___________
center; at corners
liver Acinus
- diamond–shaped
- between neighboring central vein
What are the zones of the Acinus
zones 1, 2 , and 3
The acinus Combines aspects of
- blood flow
- oxygenation
- metabolism
- pathology
What is the name of zone 1 of Heptaic Acini
perilobular zone = periportal
Zone 1 of Hepatic Acini
closest to portal tract,
Which zone of Hepatic Acini receives the most oxygenated blood?
Zone 1
perilobular zone = periportal
What zone of Hepatic Acini is most susecptible to toxic injury?
Zone 1
What it the name of zone 2 of Hepatic Acini
intermediate zone
What it the name of zone 3 of Hepatic Acini
centrolobular zone
Which Heptaic acini zone is furthest from the portal track
Zone 3
centrolobular zone
Which Heptaic acini zone is closest to the cental vein?
Zone 3
centrolobular zone
Which zone of Hepatic Acini recieves the least oxygentated blood?
zone 3
centrolobular zone
Which zone of hepatic acini is most susceptible to ichemic injury?
Zone 3
centrolobular zone
What helps the liver fucntion in detoxification/metabolism of various drugs and toxins
- microsomal mixed function
oxidase system of sER - peroxidases of peroxisomes (P450 system)
P450 system is related to
peroxidases of
peroxisomes
Cirrhosis
A common sequela to repeated insults or chronic disease
Cirrhosis is Characterized by hepatic degeneration and
necrosis
What follow necrosis in liver cirrhosis
fibrosis & nodular regeneration
Portal hypertension is associated with
cirrhosis
Portal hypertension is due to
fibrosis,
blockage of blood flow
Liver has ability to
regenerate
Gallbladder is a muscular sac located
depression
along surface of liver
Gallbladder is used to store & concentrate
bile;
volume ~100 m
The gallbladder is lined by
simple columnar epithelium
with apical microvilli
The microvilli lining the gallbladder are used for
resorption of water
Gallbladder lacks a
muscularis mucosae
Lamina propria of the gallbladder is highly folded with occasional
tubuloalveolar mucus
glands
What does CCK (cholecystokinin) stimulate?
contraction of gallbladder
What are the conponents of bile?
- water
- ions
- electrolytes
- cholesterol
- phospholipids( lecithin)
- bile acids/salts/pigments
What is the best known bile pigment?
Bilirubin
Bilirubin
non-sol breakdown product of Hb
What happens if you are unable to o absorb bilirubin or failure to
conjugate it & secrete it?
accumulation of bile
pigments = jaundice
Supersaturation of bile can lead to
gallstones
(biliary calculi, cholelithiasis)
What are the primary kind of gallstones?
cholesterol & calcium salt
choledocolithiasis
Obstruction of bile duct
cholecystitis
Chronic inflammation of the gallbladder
cholecystectomy
removal of gallbladder
If someone gets their gallbladder removed they should
limit the amount of fats they eat
due to being unable to concentrate bile
Pancreas has both
exocrine & endocrine
components
Where do you find the ductless endocrine
pancreatic tissue?
islets of Langerhan
Most of the pancreas is
exocrine (has ducts)
In the pancreas acinar cells contian
zymogen granules
zymogen granules
inactive enzyme
precursor
zymogen granules is a precursor to
- trypsinogen (protrypsin)
- chymotrypsinogen (prochymotrypsin)
- amylase
- lipase
Trypsin & chymotrypsin are
proteases
amylase breaks down
carbohydrates
lipases digest
lipids
intercalated ducts of the pancreas add
bicarbonate & water to pancreatic sections
intercalated ducts of the pancreas neutralize
acidic chyme from stomach (optimal pH for pancreatic enzymes)
Duct cells that form beginning of intercalated ductsometimes visible
in center of acini are called
centro-acinar cells
What do Intercalated ducts empty into?
larger intralobular ducts
intralobular ducts exit into
interlobular (=extralobular)
ducts
Where do pancreatic secretions enter the GI tract?
duodenum via pancreatic
duct at major duodenal
papilla
What cells secrete Gastrin?
G cells
by stomach
Gastrin stimulates
secretion of pancreatic fluid
What 3 things does teh duodenum APUD cells secrete?
- secretin
- CCK
- enterokinase
What secretes CCK?
I cells
CCK stimulates
pancreatic regulation
acinar
cells to secrete zymogens
Enterokinase converts _________ to __________
trypsinogen; trypisin
within small intestine
what
converts chymotrypsinogen to chymotrypsin
trypsin
chymotrypsin digests
proteins
Pancreatitis
autodigestion
of pancreas brought on by
alcoholism
Severe, acute pancreatitis
can be fatal within
hours
What prevents the pnacreas from digesting itself?
enterokinase converts trypsinogen to trypsin, which converts chymotrypsinogen to chymotrypsin
Cascade rxn
