Histology of Liver, Exocrine Pancreas and Gall Bladder Flashcards
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The ____________ serves as the point of entry into the liver for the hepatic arteries and the portal vein, and the exit point for the hepatic ducts.
porta hepatis
The whole surface of the liver except for the _________, is covered in a serous coat derived from the peritoneum, and this firmly adheres to the inner Glisson’s capsule.
bare area
Glisson’s capsule
A layer of connective tissue surrounding the liver and ensheathing the hepatic artery, portal vein and bile ducts within the liver.
At rest the liver normally receives about _______ of cardiac output.
25%
NOTE: The liver is unique amoung abdominal organs in having a dual blood supply, from the hepatic arteries and hepatic veins.
What are the two blood supplies of the liver?
- Portal artery
- 20-30%
- Supplies oxygen rich blood
- Portal vein
- 70-80%
- Supplies nutrient rich blood from the digestive tract
NOTE: The portal blood also contains breakdown products of hemoglobin from the spleen.
Where does blood from the head of the pancreas drain?
Superior mesenteric vein
NOTE: The tail of the pancreas drains into the splenic vein
What are the components of the portal triad?
- Branches of the hepatic artery and vein
- One or two bile ductules
- Lymphatic vessels
- Branch of vagus nerve
Explain the blood flow from the portal triads to the inferior vena cava.
Portal triads->central vein->sublobar vein->collecting vein->hepatic veins-> inferior vena cava
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What are the 3 functional units of the liver? What’s the function of each?
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Classic Hepatic Lobule
- Drains blood from the portal vein and the hepatic artery to the hepatic or the central vein
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Portal Lobule
- Drains bile from hepatocytes to the bile duct
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Hepatic Acinus
- Supplies oxygenated blood to hepatocytes
NOTE: The hepatic acinus is the most funtional way to conceptualize the liver lobule based on blood flow.

What are the 3 metabolic zones of the hepatic acinus?
Zone I
- Least oxygenated
Zone II
Zone III
- Most oxygenated

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Central veins coalesce into __________.
Hepatic veins
*Which leave the liver and empty into the vena cava
Purpose of the liver sinusoid
A liver sinusoid is a type of a capillary similar to a fenestrated capillary and serves as a location for mixing of oxygen rich blood from the hepatic artery and the nutrient rich blood from the portal vein
How does the liver sinusoids differ from other capillaries?
- Larger
- Lining of specialized endothelial cells, known as liver sinusoidal cells (LSEC)
Basolateral surface of the hepatocyte faces ______, and apical surfaces face ___________.
Sinusoids; bile canaliculi
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Characteristics of the nucleus of hepatocytes
- Prominent nucleolus
- Dispersed chromatin
- Polyploidy
Characteristics of the cytoplasm of hepatocytes
- Glycogen lacey appearance
- Fat spherical vacuoles
- Ribosomes and RER basophilia
- Mitochondira- eosinophilic
- Lysosomes
- Golgi complex
- Peroxisomes
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Most of the glucose absorbed from a meal is stored as _________ in the liver.
Glycogen (5-6% of the liver’s fresh weight)
NOTE: Glucose is also stored in muscles
Blood glucose enters hepatocytes via which transporter?
GLUT2
The human body can store up to _____ grams of glycogen.
450
*A third of this is stored in the liver
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Glycogen
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Which structure of hepatocytes function to synthesize and secrete plasma proteins?
RER
Ex: Albumin, fibrinogen, thrombin
Which structure of hepatocytes function to synthesize and secrete bile?
SER
- Bile acids from cholesterol
- Elimination of bilirubin
- Secretion of secretory IgA
Which structure of hepatocytes function to metabolize carbohydrates?
SER, cytosol
Which structure of hepatocytes function to metabolize lipids?
RER
Which structure of hepatocytes function to maintain normal levels of blood lipids?
VLDL
Function of the smooth endoplasmic reticulum
- Synthesis lipids, oils, phospholipids, steroids, and sex hormones
- Hydrolysis of glycogen into glucose
- Detoxification of drugs and poisons
- Pumps calcium ions for muscle function

___________ are spaces present between the plasma membrane of adjacent liver cells.
Bile canaliculi

Flow of bile
Bile canaliculi-> Canals of Hering-> intrahepatic bile ductule (in portal triad)->Interlobular bile ducts-> left and right hepatic ducts-> Common hepatic duct
NOTE: The common hepatic duct joins with the cystic duct which becomes the bile duct, which enters the duodenum
Function of Kupffer cells
Continuously sample the blood travelling through the sinusoids, phagocytosing antigens, microorganisms and damaged red blood cells.

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Which component of hepatocytes is being described below?
- A subendothelial space
- Space between hepatocytes and sinusoidal lining cells
- Microvilli of hepatocytes project into the space
- Fat storing stellate cells that store Vitamin A found here
- Space continuous with sinusoids
- Space drains to lymphatics of portal triad
Space of Disse

Which component of hepatocytes is being described below?
- Lie in perisinusoidal space
- Have long cytoplasmic processes that extend below the endothelial cells
- Contain actin and myosin and contract in response to endothelin and substance P
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Contribute to regulate the diameter of the sinusoid
- Store fat and Vitamin A
Ito (stellate cells)

Ito cells can proliferate when activated by _____ and ________.
Kupffer cells; hepatocytes
What happens to Ito cells in pathological conditions?
- They change into collagen producing cells
- They secrete type I collagen leading to fibrosis of the liver
- As the fibrotic process advances, ito cells change into myofibroblasts which contrict the lumen of the sinusoids and increase vascular resistance
- An increase in resistance to the flow of blood in the hepatic sinusoids leads to portal hypertension

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Which portion of the pancrease makes and secretes digestive enzymes into the duodenum?
Exocrine
NOTE: This includes secretory acinar and duct cells with associated connective tissue, vessels, and nerves.
Components of exocrine pancreas
NOTE: Most pancreatic enzymes are produced as zymogens, which help minimize the risk of self digestion within the pancreas

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What are the two portions of the cytoplasm of each acinar cell?
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Apical
- Filled with eosinophilic protein secretory granules
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Basal
- Strongly basophilic
- Replet with RER
What accounts for the dark appearance of secretory ganules?
High concentration of proteins (enzymes) and other macromolecules
NOTE: Secretory granules are primarily found in the apical side of the cell. Fusion with the plasma membrane releases the contents of the granules into the extracellular space.
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What are the two secretory products of pancreatic juice?
- Digestive enzymes
- Synthesized and secreted from the exocrine acinar cells
- Bicarbonate
- Secreted from the epithelial cells lining small pancreatic ducts
When is secretin secreted?
In response to acid in the duodenum which stimulates duct cells to produce water and bicarbonate
How is merocine secretion of proenzymes by acinar cells regulated?
- Secretin
- Cholecystokinin
- Nerve stimulation from the vagus nerve
Components of acinar cells of the pancreas
- Trypsin
- Chymotrypsin
- Elastase
- Sodium bicarbonate
How is trypsinogen activated?
- By enterokinase, which is embedded in the mucus membrane of the duodenal mucosa
NOTE: Trypsin is autocatalytic which means that trypsin, once activated, forms more trypsinogen, which is then activated to trypsin
Chymotrypsinogen and procarboxypeptidase are converted to an active form by ______ in the duodenal lumen.
Trypsin
Bile empties to the common bile duct under ________ stimulation.
Hormonal
NOTE: Cholecystokinin stimulates the gallbladder. Cholecystokinin (CKK) is secreted by the I cells of the intestinal mucosa.

Once stimulated by CCK, how does the gallbladder respond?
By contracting and delivering more bile to the duodenum through the Sphincter of Oddi, which relaxes (opens) in response to CCK.
Function of bile
- Excretion of cholesterol, phospholipids, bile salts, conjugated bilirubin and electrolytes
- Contributes to fat absorption in the intestinal lumen
- Transports IgA to the intestinal mucosa by enterohepatic circulation
- Excretion of metabolic products of drugs and heavy metals processed in the hepatocyte
- Conjugated bile acids inhibit the growth of bacteria in the small intestine
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What are the 4 layers of the gall bladder?
- Lining epithelium (simple columnar)
- Lamina propria
- Rich in elastic fibers and blood vessels
- Muscularis
- Consists of circularly arranged smooth muscle fibers intermixed with connective tissue rich in elastic fibers
- Serosa/ adventitia
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Cholecystitis
- Inflammation of the gall bladder
- Rokitansky-Aschoff sinuses- herniation of mucosa into muscular wall