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103 Cards in this Set
- Front
- Back
How much does the liver weigh?
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Between 1200 - 1500 grams
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What blood does the liver recieve?
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Veinous blood from the
-Spleen -Pancreas -Intestine |
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2 major functions of the liver:
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-Detoxify substances
-Absorb nutrients |
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What is the liver enveloped by?
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Peritoneum
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What type of epithelium is the peritoneum?
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Simple squamous
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What does the simple squamous epithelium cover?
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The Dense irregular CT capsule called Glisson's capsule
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Where is the glisson's capsule not loosely attached to the liver?
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At the porta hepatis
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What happens to it at the porta hepatis?
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It enters the liver to form a conduit for the blood, lymph vessels, and bile ducts.
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Does the liver have much connective tissue?
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no
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What is the bulk of the liver formed by?
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Parenchymal cells
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What are parenchymal cells?
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Hepatocytes
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What supplies blood to the liver? (3 vessels)
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-Right hepatic artery
-Left hepatic artery -Portal vein |
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How does blood leave the liver?
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Via the hepatic veins
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Where does bile leave the liver and go?
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Via the bile duct to the gallbladder.
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2 properties of the liver:
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-Endocrine
-Exocrine |
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Where do the endocrine secretions come from and go?
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-Directly from the hepatocytes
-Into the hepatic blood |
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What is the main exocrine function of the liver?
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Secretion of bile
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What are the 4 functional groups of hepatic components?
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1. Connective tissue
2. Large vessels 3. Sinusoidal capillaries 4. Hepatocytes |
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What do the large vessels include?
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Blood vessels
Lymphatic vessels Nerves Bile ducts |
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What are sinusoids?
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Sinusoidal capillaries that line plates of hepatocytes
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What is an important hormone that is sereted by hepatocytes?
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Thyroxin
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How does the liver function in metabolism?
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-Maintains normal glucose levels in the blood by 1. Storing glycogen, 2. Releaseing it when needed, and 3. Making it from other noncarb sources/sugars
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When hepatocytes break down glycogen via glycogenolysis, where do they release it into?
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The space of Disse
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What type of capillaries make up the sinusoidal capillaries between cords of hepatocytes?
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Fenestrated
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Do these fenestrated capillaries have a basement membrane separating them from the hepatocytes?
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No; blood can freely wash over the hepatocytes as it flows in and out of the fenestrations.
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What is the space between the endothelial cells of sinusoidal caps and the hepatocyte cords?
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The space of disse
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What does the space of disse contain?
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Reticular fibers made of Type III collagen
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What does the reticular network extend out from?
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The central vein of each lobule
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What other connective tissue is in liver lobules?
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That's it - just the reticulin
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What is the function of the Reticulin?
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To support the hepatocytes and keep the sinusoids open
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What cells make the reticulin? Where?
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Ito cells, aka Stellate cells - in the space of disse
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What is thickened and abnormally prominent reticulin between the hepatocytes and sinusoids a sign of?
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Hepatic cirrhosis
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What causes hepatic cirrhosis?
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Hepatic necrosis
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What is the hepatocyte's response to necrosis?
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1. Collapse of hepatic lobule organization
2. Nodular regrowth 3. Fibrosis |
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What causes the fibrosis in hepatic cirrhosis?
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Increased activity of the stellate cells, depositing more type I and III collagen.
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How many major vessel systems are in the liver? What are they?
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FIVE:
1. Hepatic artery 2. Hepatic portal vein 3. Central veins 4. Bile ducts 5. Lymphatic vessels |
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What does the hepatic artery carry?
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Oxygenated blood from the arteries
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What does the Hepatic portal vein carry?
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Venous blood from the organs to the liver
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What do central veins carry?
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Blood away from the liver to the hepatic veins, to eventually dump into IVC
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How does blood go from the huge hepatic artery, carrying the blood with RBC brkdown products, digested food, pancreatic enzymes, etc, to the sinusoids?
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Via Arterial capillaries and inlet venules that branch off from it.
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What blood flows into the sinusoids?
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BOTH
-Portal vein (nutrient-rich) -Hepatic artery (O2-rich) |
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What does a Portal Triad consist of?
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-Branch of Hepatic artery
-Branch of Hepatic portal vein -Bile duct |
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Where does the blood from the 2 arteries in the triad go?
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Down the sinusoids, then dumps into the central vein.
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What happens to central veins?
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They join together to flow into the IVC
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What 2 types of cells make up the sinusoids?
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-Sinusoidal endothelial cells
-Kuppfer cells |
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What are Kupffer cells?
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Specialized macrophages that possibly breakdown senescent RBCs
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So where does exchange between blood and hepatocytes take place?
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In the Space of Disse
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On what sides of the hepatocyte are the Space of Disse?
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On each of its 2 basal sides.
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What special surface feature do hepatocytes have on their basal side?
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Microvilli
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What cells are found in this Space of disse?
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Stellate/Ito cells
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What are these Ito cells?
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Adipocytes
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Why are Ito cells important?
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They store vitamin A! And make reticulin of course.
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What are the functional units of the liver?
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Lobules
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In what directions do bile and blood flow?
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Opposite
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How is the classic lobule described?
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-Hexagon
-6 portal triads at each point -1 central vein |
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Why is it hard to see the classic lobule in humans?
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Because our CT is not as thick as that in pigs
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Where are the basal surfaces of hepatocytes?
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Facing the sinusoid
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Where are their apical surfaces?
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Facing the bile ducts
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Where are their lateral surfaces?
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Facing adjacent hepatocytes
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What are the cell structures and genetics of hepatocytes like?
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-Rich in organelles
-Binucleate -Tetraploid (4N) |
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What are the predominant organelles that reflect the high metabolic activity of hepatocytes?
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-RER, Mitochondria
-Glycogen granules -Lipid droplets |
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What would a "portal" lobule consist of?
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A triangle:
-3 central veins -1 portal triad at the middle |
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What is an "Acinus" functional unit?
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A lozenge shaped unit, with 2 triads making up the short axis and 2 central veins making up the long axis.
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So instead of blood flowing from the 6 edges toward the center, how does it flow in the acinus?
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From the middle toward the 2 opposite ends
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How does the way in which blood perfuses the acinus allow us to look at hepatocytes?
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In terms of their order of encountering blood.
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What are the 3 concentric zones of hepatocytes within the acinus?
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Zone 1 - encounters first
Zone 2 Zone 3 - encounters last |
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Which cells are the last to die and first to regenerate if circulation is impaired?
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The zone 1 cells - they encounter the best blood
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Which cells are first to show ischemic necrosis and fat accumulation?
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Zone 3 cells
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Which cells are the last to respond to toxic substances and bile stasis?
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Zone 3
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So the principle functional cell of the liver is the:
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hepatocyte
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How many cells thick are the plates of hepatocytes that make up cords?
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1-2
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What are hepatocytes really?
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Epithelial cells with 6 sides
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Main exocrine function of the liver:
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production of bile
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What does bile consist of?
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An isotonic solution of water and electrolytes
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What causes jaundice?
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Failure to remove bilirubin
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What do bile acids come from?
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Cholesterol metabolism
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What side of hepatocytes does bile come out of?
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The apical side
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Where does it go?
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Into bile canaliculi
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Where are bile canaliculi?
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Around hepatocytes
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What do canaliculi join together to form?
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Canals of herring - ductules
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What are bile ducts made of?
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Biliary epithelial cells
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What type of epithelial cells?
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Cuboidal
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Where do the bile ductules drain into?
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The bile ducts at the portal triad
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Where do bile ducts drain?
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Into the hepatic duct back at the portal entrypoint of the whole liver
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How much bile does the human liver secrete daily?
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1 liter
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Where does bile go from the hepatic duct? Why?
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To the gallbladder to be concentrated
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What is formed when the hepatic duct joins the cystic duct?
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The common bile duct
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What joins with the common bile duct?
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The pancreatic duct
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What stimulates the gall bladder to contract and release concentrated bile into the duodenum?
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CCK
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What stimulates CCK release?
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The presence of fat in the duodenum
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What is the gallbladder like structurally? how much can it hold?
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A muscular sac
-holds up to 100 mls per day |
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What does the lumen of the gallbladder feature?
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Numerous deep mucosal folds with apical microvilli on simple columnar epithelial cells
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what does the lumen of the gallbladder resemble?
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The absorptive cells of the intestine
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How does the gallbladder concentrate bile?
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By actively absorbing water into its epithelial cells, then into a capillary network in its lamina
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Do the mucosal folds of the gallbladder lumen go away when it is distended?
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no
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What is the most common disease associated with the gallbladder?
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Cholethiasis - gallstones
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What is treatment?
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Removal of gallbladder
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Can the LIVER regenerate?
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yes - partial hepatectomy is a model for it
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When liver lobes are dissected out of rodent livers, do they grow back?
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No, but the remaining lobes enlarge to make up for the removed mass.
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What types of liver cells regenerate?
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All types
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What regulates liver regeneration?
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Both pos and neg signals
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Can transplanted hepatocytes efficiently repopulate damaged livers?
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Yes
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What are oval cells?
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A potential source of hepatic stem cells in the bone marrow
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