Liver and Pancreas Flashcards
What is the direction of bile flow with respect to blood?
Opposite
Define bile flow in liver
Bile canaliculi -> canals of Herine (small bile ductules) -> bile duct ->hepatic ducts -> cystic duct ->intestines -> portal vein -> liver sinusoid -> hepatocytes -> bile canaliculi
What does bile contain?
Cholesterol, phospholipids, bile salts, conjugated bilirubin, electrolytes
How do we remove conjugated bilirubin from our systemsystem?
Secreted via bile
What is a silent killer that obstructs bile?
Pacreatic carcinoma
What is obstructed blood flow in the liver leading to fluid accumulation in peritoneal cavity (ascites)
Portal Hypertension
Why is billirubin usually conjugated? What is a disease that leads to excess bilirubin
Free bilirubin is toxic to brain. Erythroblastosis fetalis, or blood group incompatibility between mother and fetus, can result in hyperbilirubinemia
Why does excess alcohol lead to liver injury?
In metabolizing alcohol, pathways can produce acetate, excess hydrogen ions, and free radicles, leading to liver stress
What leads to fibrosis?
Anything that causes systemic inflamation (alcohol, viral, bacterial toxins)
Describe pathway of cirrhosis
Cytokines are released from Kupffer cells due to inflammation, in response hepatic stellate cells transform to myofibroblasts and produce collagen, leading to fibbrosis
What causes release of bile from gallbladder
Cholecystokinin
What is the key feature of the gallbladder?
Diverticula of the epithelium - outpocketings of mucosa that form epithelial lined cysts in the lamina propria (Rokitansky-Aschoff sinuses)
What is the epithelium of gallbladder mucosa?
Simple columnar epithelium with microvilli on apical surface
What do we mean when we say that gallbladder has no true submucosa
Lamina propria loose connective tissue blends with epithelium basement membrane
What is the muscularis externa of the gallbladder
Is the pancrease an endocrine or exocrine secretor?
Both!
What has considerable connective tissue in between lobules of septa?
Interlobular ducts for exocrine secretion
What is most abundant endocrine cell? What do alpha, beta, delta, and epsilon cells produce?
Beta cells.
Beta cells - insulin, alpha cells, glucagon, delta cells, somatostatin, epsilon cells, ghrelin
What do each of these hormones do?
Why do enzymes start in proenzyme form in the pancrease?
So that they do not digest pancreatic tissue
What does the pancrease secrete via exocrine secretion
Amylase, lipase, ribonuclease, deoxyribonuclease, trypsin, chymotrypsin, carboxypeptidase, elastase enzymes, enzyme poor alkaline fluid (bicarbonate)
What causes each secretion?
What is the flow of exocrine secretions?
Intercalated ducts (centroacinar cells), intralobular ducts (cuboidal epithelium), interlobular ducts (large amounts of pancreatic tissue), main pancreatic duct
What is Type 1 Ddiabetes mellitus?
Low levels of plasma insulin, polydipsia, polyuria, polyphagia
What causes Type II diabetes?
Faulty signalling due to impaird insulin release, decreased insulin receptors, faulty post-receptor signalling
What are two characteristic resistances of insulin resistant diabetes?
Hepatic insulin resistance, muscle insulin resistance
What causes Hepatic insulin resistance?
Faulty signalling through docking molecules (insulin receport substrate) proteins that connect insulin receptor activation to downstream kinase cascades such as P12K or MAPK
What is pancreatitis and what commonly causes it?
Inflammation of pancreas - often due to gallstones
What type of pancreatitis leads to digestion of pancreatic tissue? What can cause it?
Acute necrotizing pancreatitis
Can be caused by infection, gallstones, drugs, trauma
What are the functions of the liver?
Gluconeogenesis, detoxification, storage, production of plasma proteins, production of bile, and transfer of IgA into canaliculi
What mixes in the liver sinusoid?
Blood from hepatic artery and portal vein, portal vein major contributor
Is the majority of pancreas exocrine or endocrine?
The MAJORITY is exocrine, does both
Name the plasma proteins produced by the liver
fibrinogen, prothrombin, albumin, urea, acute phase proteins (endocrine secretions)
What subdivides the liver into lobes and lobules?
A fibroconnective tissue capsule (Glisson’s capsule)
What kind of cells are hepatocytes?
Parenchymal cells
What organelles are particularly abundant in hepatocytes
rEr, sEr lysosomes, peroxisomes, mitochondria
Describe the classical liver lobule
Defined division of liver as hexagonal hepatocyte plates organized around a central vein (not easy to see histologically)
Where is bile secreted?
Space in between cells called canaliculi
Describe the nuclei of the liver
Binculeate with large nuclei and 2x normal DNA - some are polyploid,. Liver cells therefore can divide if part of liver is lost
What is the key identifying feature of the liver?
The portal canal
What is the portal canal (triad, area)
Branches of portal vein, hepatic artery, and bile duct grouped together around lobule. Often lymph vessel is present
Trace the flow of blood through the liver
Portal vein and hepatic artery -> sinusoids -> out endothelial fenestrations into Space of Disse -> back in through fenestrations -> central vein
What kind of endothelium do sinusoids have?
Discontinuous endothelial lined spaces in-between plates of hepatocytes, large fenestration, and Kupffer cells
What is a Kupffer cell?
Phagocytic cells of monocyte lineage
Where is the space of Disse located? What is its purpose?
Space of Disse is located between the endothelium of the sinusoids and the microvilli of the hepatocytes
What is a portal lobule?
Lobule defined by portal area and the flow of bile, includes three central veins centered around a bile duct.
What is the hepatic acinus of Rappaport?
What are the zones in the hepatic acinus and what function does each zone perform?
Defined by metabolic gradient, region between two veins that defines oxygen gradients.
Zone 1is highly oxygenated and performs oxidative functions-cholesterol synthesis, gluconeogenesis, plasma proteins.
Zone 2 - intermediate region
Zone 3 - low O2 area - Hepatocytes serve role in detoxification and is susceptible to hypoxia
What cells store fat in the Space of disse? What vitamin do they also store and metabolize? What happens when they are diseased?
Hepatic stellate cells/cells of Ito.
Important for Vit A storage and metabolism
Produce collagen in response to cytokines from Kupffer cells leading to cirrhosis
What is the purpose of bile?
Facilitates absorbtion of fat and fat soluble vitamins
How much bilic acid is reabsorbed in ileum?
90%
What is the name for bile reuse and recirculation
Enterohepatic recirculation
How does bile relate to IgA
Bile carries IgA complexed from hepatocytes
What else can bile excrete?
Drugs and heavy metals
What is Hepatitis? What is the difference of infection between A, B, C
Inflamation of liver. Virus A - infectious fecal, oral route, B - serum hepatitis-blood & blood products, C- transfusion related- hepatocellular carcinoma
What is degeneration and fibrosis of liver?
Cirrhosis
What causes cirrhosis
Poisoning, chronic alcohol use, bile duct obstruction, long term ETOH consumption with lipid deposits or steatosis
How does the liver relate to jaundice?
Liver dysfunction obstructs bile passages yields excess bilirubin in blood and bile pigment in skin and sclera of eye. Can result in RBC destruction
