Liver, Gallbladder And Exocrine Pancreas Flashcards by Scarlett Enright

Principle cells of the liver

Hepatocytes

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Arrangement of hepatocytes in liver

Arranged in cords with intervening sinusoids

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Portal tract/triad comprises of…

Branches of portal veins
Hepatic Arteries
Bile ducts

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Classic lobules

Liver divided into classic lobules- architectural concept based on blood drainage
Area drained by one central hepatic venule
Roughly hexagonal
Each point of hexagon = portal tracts
Centre = central vein

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Acinus

Architectural concept based around the blood supply rather than the drainage
Diamond shape
Portal tracts on the ends of the short axis of the acinus
Central vein on ends of long axis of acinus

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Hepatocytes in the lobule

Not all equal
Some Hepatocytes are more richly oxygenated than others:
-closest to edge of lobule
-nearest to portal vein
-nearest to hepatic arteries
Hepatocytes surrounding central vein are relatively deprived of oxygen and glucose

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Blood flow within lobule

Blood flows from the portal tract through the sinusoids between the cords of Hepatocytes and drains into the central vein

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What is the largest solid organ in the body

Liver

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Function of Hepatocytes

Creation and storage of energy in the form of glycogen and fats
Synthesis and secretion plasma proteins
De-amination of amino acids and production of urea
Uptake, synthesis and excretion of bilirubin and bile acids
Detoxification and inactivation of drugs and toxins by oxidation, methylation or conjugation

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Structure of Hepatocytes

Polyhedral epithelial cells
Abundant mitochondria
Large central spherical nuclei
Prominent nucleoli
May be binucleate

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4 macroscopic lobes of liver

Left
Right
Caudate
Quadrate

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3 surfaces of Hepatocytes

Sinusoidal (70%)
Canalicular (15%)
Intercellular (15%)

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Sinusoidal surface of Hepatocytes

Permits exchange of material with blood- space of Disse

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Canalicular surface of Hepatocytes

Permits excretion of bile

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Space of Disse

Peri-Sinusoidal space
Contains reticulin fibres (collagen III)
Contains ito cells (stem cells)

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Sinusoids

Fenestrated thin-walled capillaries
No basement membrane
Contains scattered Kupffer cells (fixed macrophages) and ito cells
Carry a mixture of venous (70%) and arterial (30%) blood that bathes the cords of liver cells

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What are kupffer cells derived from

Blood monocytes

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Intrahepatic biliary tree

Simple cuboidal-to-columnar epithelium
Canaliculi—>bile ductules —> trabecular ducts —> bile ducts

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Where are canaliculi located

In between individual hepatocytes

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As the size of the duct increases, how does the height of the epithelium change

Increases
Eg extrahepatic ducts lined by simple columnar epithelium

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Functions of gallbladder

Concentrates and stores bile
Expels bile via common bile duct into duodenum

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Which duct carries bile from the gallbladder into the duodenum

Common bile duct

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How does the gallbladder concentrate bile

Absorbing water

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Gallbladder epithelium and structure

Simple columnar epithelium
Mucosa comprising loose, fibrous connective tissue below
No muscularis mucosae
Muscularis propria = Thick layer of smooth muscle

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Layers of gallbladder wall

Simple columnar epithelium Specialised mucosa Muscularis propria Adventitia

Specialised mucosa of gallbladder

Simple columnar epithelium Microvilli Thrown into folds- adapted for water and salt absorption Connective tissue Lamina propria

Function of exocrine pancreas

Synthesise and secrete enzymes and bicarbonate-rich fluid into the duodenum

Structure of exocrine pancreas

Surrounded by a Poorly defined fibrous capsule with septa dividing gland into lobules Epithelial cells arranged in acini

Acinar cells of exocrine pancreas

Epithelial Pyramidal shape Basally- rich in rER apically- zymogen granules (enzyme precursors)

Duct system of exocrine pancreas

Centroacinar cells —> intercalated ducts —> interlobular ducts —> main pancreatic duct

Lining of interlobular ducts of pancreas

Simple cuboidal epithelium to low columnar cells

Lining of main pancreatic duct

Alumna

What separates the polygonal lobules of the liver

Delicate connective tissue septa

What is stored within hepatocytes

Large quantities of glycogen and triglyceride

Purpose of the concept of liver acinus

Helps to explain the variations in metabolic activity that occurs within a lobules

What composes the mesh work that sinusoids rest on

Reticulin (collagen III fibres)

Role of Kupffer cells

Phagocytose and destroy blood borne pathogens that pass through the liver Responsible for production of bilirubin that is subsequently taken up and excreted by hepatocytes

Sinusoidal membrane of hepatocytes function

Transport mechanisms for the uptake of nutrients and pinocytotic release of macromolecules

Canalicular membrane of hepatocytes function

Target for discharge of bile

Rosettes

Glycogen particles present in hepatocytes

Lining of biliary tree

Cuboidal epithelium In smaller vessels = simple Towards distal end = stratified

What percentage by mass is the exocrine pancreas if the gland

90%

Exocrine pancreas

Wholly serous gland- watery secretion, enzyme rich

Secretin and exocrine pancreas

Induces release of an alkaline fluid which is mainly produced by centre-acinar cells and small duct cells

CCK and exocrine pancreas

Causes the release of enzymes from the cells by exocytosis

Bile canaliculi

Extra-cellular channels between hepatocytes into which the hepatocytes secrete bile These channels coalesce at the edges of the liver lobules and drain the bile into bile ductules that form part of the portal triad

Do liver cells replicate?

Yes, bi-nucleate liver cells (in the process of division) constitute 2%-3% of the liver mass Liver is capable of substantial regeneration

Ito cells

Lie in sinusoids of liver Fat-storing cells that play a pivotal role in the fatty degeneration and fibrosis of the liver eg in cirrhosis

Where is the water absorbed by the gallbladder passed into

Venules and veins in the walls of the sac

Which hormone causes the gallbladder to contract

Cholecystokinin CCK

Where is cholecystokinin produced

Endocrine cells in walls of duodenum

When is cholecystokinin released

In response to fat arriving in the duodenum from the stomach

Which nerve supplies the pancreas with secretor-motor fibres

Vagus nerve

What mechanism prevents the proteolytic enzymes from digesting the pancreas

Secreted in the inactive form as zymogens and are normally only activated when they reach the duodenum In some forms of pancreatitis the gland breaks down autolytically

Pacinian corpuscle

Pressure sensors Found in the pancreas

Islet of Langerhans

Contain endocrine cells including beta cells that produce insulin

What product in particular does the splenic branch of the hepatic portal vein carry to the liver

Iron carrying ferritin

How are the products transported from the spleen processed by the liver

Ferritin (a protein with an iron core) is discharged by the spleen and is picked up by Kupffer cells in the liver

Ferritin

A protein with an iron core

Which hepatocytes have higher glycogen concentrations

Periphery of the lobules

Which hepatocytes are glycogen removed from first

Hepatocytes closer to the centre of a lobule

2 most important proteins continuously synthesised by the liver

Serum albumin Fibrinogen

Paracetamol poisoning causes centrilobular death of hepatocytes, Which of the following lies at the centre of the classic liver lobule?

Central hepatic venule

In the lobule , which direction does blood flow

Towards the centre

Number of zones in acinus

Zone 1 of acinus

Zone 1 encircles the portal tracts where the oxygenated blood from hepatic arteries enters.

A 24 year old man with a hepatitis A virus infection develops fulminant liver failure. Which of the following is a function of hepatocytes?

Bile synthesis

Pruritus

Itching

Which of the following statements regarding hepatocytes is true?

Usually contain glycogen

Fat in the liver is stored in

Hepatocytes Ito cells

A 45 year old man with infertility, diabetes mellitus and cirrhosis of the liver undergoes a liver biopsy, which looks like this. Which statement regarding the blue Kupffer cells is true?

Lie in sinusoids

The patient has haemochromatosis, which causes iron overload in the liver, pancreas, skin and gonads. What stain has been used to stain these cells blue?

Perls’ stain

What do pancreatic Acinar cells secrete

Chymotrypsinogen

What do pancreatic Acinar cells look like on a slide

Large magenta cells - fluffy

What do pancreatic ductule cells secrete

Bicarbonate ions

Liver, Gallbladder And Exocrine Pancreas Flashcards

(75 cards)