Liver, Gallbladder And Exocrine Pancreas Flashcards
Principle cells of the liver
Hepatocytes
Arrangement of hepatocytes in liver
Arranged in cords with intervening sinusoids
Portal tract/triad comprises of…
Branches of portal veins
Hepatic Arteries
Bile ducts
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
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
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
Blood flow within lobule
Blood flows from the portal tract through the sinusoids between the cords of Hepatocytes and drains into the central vein
What is the largest solid organ in the body
Liver
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
Structure of Hepatocytes
Polyhedral epithelial cells
Abundant mitochondria
Large central spherical nuclei
Prominent nucleoli
May be binucleate
4 macroscopic lobes of liver
Left
Right
Caudate
Quadrate
3 surfaces of Hepatocytes
Sinusoidal (70%)
Canalicular (15%)
Intercellular (15%)
Sinusoidal surface of Hepatocytes
Permits exchange of material with blood- space of Disse
Canalicular surface of Hepatocytes
Permits excretion of bile
Space of Disse
Peri-Sinusoidal space
Contains reticulin fibres (collagen III)
Contains ito cells (stem cells)
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
What are kupffer cells derived from
Blood monocytes
Intrahepatic biliary tree
Simple cuboidal-to-columnar epithelium
Canaliculi—>bile ductules —> trabecular ducts —> bile ducts
Where are canaliculi located
In between individual hepatocytes
As the size of the duct increases, how does the height of the epithelium change
Increases
Eg extrahepatic ducts lined by simple columnar epithelium
Functions of gallbladder
Concentrates and stores bile
Expels bile via common bile duct into duodenum
Which duct carries bile from the gallbladder into the duodenum
Common bile duct
How does the gallbladder concentrate bile
Absorbing water
Gallbladder epithelium and structure
Simple columnar epithelium
Mucosa comprising loose, fibrous connective tissue below
No muscularis mucosae
Muscularis propria = Thick layer of smooth muscle
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
3
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
