Liver, Gallbladder, Pancreas Histology

Question 1

locate the boundaries of the hepatic lobule and describe the directional flow of blood, including the vessels that supply the blood

Answer 1

the central vein surrounded by six portal triads; is the structural unit defining blood drainage to the central vein

Question 2

describe the structures present in the portal triad and recognize these structures in a tissue section

Answer 2

1. hepatic artery: a small muscular arteriole
2. portal vein: large venous structure
3. bile duct: line with cuboidal epithelium

Question 3

recognize sinusoids and central veins and understand their role in the blood flow within the hepatic lobule

Answer 3

sinusoids are larger than capillaries with a modified endothelial lining that promotes interaction of elements in blood vasculature with hepatocytes and endothelium tends to overlap with large clefts between adjacent cells so is sinusoidal;

central veins are at the center of the hepatic lobule and also have a discontinuous tunica intima, is the largest tributaries of the hepatic veins

Question 4

differentiate between hepatocytes and hepatic macrophages (Kupffer cells)

Answer 4

hepatocytes are separated from sinusoids by the perisinusoidal space, the macrophages reach into this space from the sinusoids to keep it clean

Question 5

describe the triangular hepatic acinus with its 3 zones of metabolic activity

Answer 5

the two base points of the triangle are portal triads and the apex of the triangle if the central vein

zone 1 is closest to central vein, is first to receive oxygen, nutrients, and also toxins
zone 2 is intermediate zone
zone 3 is closest to portal triad; last to receive nutrients and oxygen so is first to suffer from low O2

Question 6

ID the type of epithelium that lines the gallbladder

Answer 6

simple columnar

Question 7

differentiate between the exocrine and the endocrine portion of the pencreas

Answer 7

endocrine is pancreatic islets/islets of langerhans (no ducts) and exocrine is everything else

Question 8

relate the physiology of the exocrine portion of the pancreas to the microscopic anatomy by describing the pancreatic acinar cell cytoplasm (acidophilic or basophilic) and locating the zymogen granules. why do the acinar cells have zymogen granules?

Answer 8

pancreatic acinar cell cytoplasm is basophilic and contains a lot of RNA, but the apical part of the cell is intensely acidophilic since it is full of packaged secretory product, zymogen granules, that contain digestive proenzymes

Question 9

differentiate between the pancreatic acinar cells and centroacinar cells

Answer 9

pancreatic acinar form pancreatic acini of secretory units (tubuloacinar in shape) and contain zymogen granules; centroacinar cells are at the beginning of the duct system, are more euchromatic, and look bright like diamonds and lead to intercalated ducts

Question 10

differentiate between intralobular and interlobular ducts

Answer 10

intralobular ducts form from intercalated ducts (which come from diamond-like centroacinar cells); intralobular ducts have less CT surrounding them than interlobular ducts, which are found in expanded interlobular regions that contain greater amounts of CT

Question 11

describe the stroma of the pancreas

Answer 11

thin CT capsule that envelopes each lobe and sends septa into the parenchyma which supports the vascular system and bile ducts

Question 12

describe hepatocytes (3)

Answer 12

1. polyhedral with round nuclei (often binucleated)
2. compose over 80% of liver cells
3. arranged in a series of branching and anastomosing plates to form a spongework for blood flow

Question 13

describe bile canaliculis and
describe the flow of bile as illustrated illustrated by the portal lobule

Answer 13

located between adjacent hepatocytes, come together at the periphery of lobes to form small ductules that flow into larger ducts with more CT around them and ultimately collect in definitive bile ducts with cuboidal to columnar epithelium

flow of bile: bile canaliculi to interlobular ducts to lobar ducts to hepatic ducts to the common bile duct

Question 14

what are the 2 types of jaundice? describe

Answer 14

prehepatic: increased destruction of RBCs
hepatic: liver dysfunction

Question 15

what are the 3 functional units of the liver? describe

Answer 15

1. classic hepatic lobule: central vein surrounded by six portal triads; the structural unit defining blood drainage to the central vein
2. portal lobule: portal triad/region at the center with a central vein at each corner of the triangle; defines the drainage of bile into exocrine ducts
3. liver acinus: diamond-shaped structure with a central vein at opposite corners and portal triad; correlates blood supply with metabolic activity and fits with pathologic changes that occur in liver during disease

Question 16

what are the 2 parts of the exocrine portion of the pancreas? function? type of gland?

Answer 16

1. acini: tubular or pear shaped groupings of pancreatic acinar cells and centroacinar cells
2. duct system: similar to that of salivary glands but without striated ducts
   function is to make pancreatic juice (alkaline pH, digestive enzymes); compound tubuloacinar glands