Lecture 33: Liver And Pancreas

Question 1

Describe the general histological organization of the pancreas

Answer 1

Pancreas:
Lobulated, compound, tubulo-alveolar gland w/ exocrine/endocrine secretory function.

CT support:no organized capsule, thin layer of loose CT from which septa pass internally dividing the gland into many small lobules.

Question 2

Describe intercalated ducts and their secretion

Answer 2

Duct of wirsung is main excretory duct.

Duct of santorini is the smaller accessory duct.

Interlobular ducts: lined w/ simple columnar epithelium w/ goblet cells.

Divide further into intercalated ducts: lined w/ low cuboidal, receptors for secretin. Cells secrete water and bicarb.

Question 3

Describe the histo of the pancreatic acinus and know function of acinar, centroacinar, and ductal epithelial cells

Answer 3

Pancreatic acini=
are serous and formed into pyramid shaped cells. Basophilic. Trypsin, chymotrpysin, ENZYMES

Centroacinar cells: form truncated cuboidal eppithelium w/ lumen of acini. Continuous w/ epithelium of intercalated duct. Unique to pancreas.forms bicarbonate.

Ductal epithelial cells: bicarbonate-rich, alkaline fluid is released in response to secretin.

Question 4

Know action of secretin and CCK on pancreatic acini.

Answer 4

CCK= release of digestive enzymes from serous acinar cells

Secretin= secretion of bicarbonate ions is regulated by secretin. Secreted by duodenal enteroendocrine cells when stimulated by food entering small intestine.

synthesis of of bicarbonate ions. Bicarbonate-CO2 diffuses into intercalated ducts from blood

Question 5

Be able to describe synthetic pathway of pancreatic bicarbonate ions.

Answer 5

1. CO2 diffuses into intercalated ducts from blood
2. CO2 + water-> carbonic acid (req’s carbonic anhydrase)
3. Carbonic acid->HCO3 +h+
4. HCO3 is actively transported to lumen of intercalated duct.
5. Na+ and H+ are exchanged w/ Na+ flowing into duct lumen and H+ flowing into blood.

Question 6

Describe the function of each of the 3 types of pancreatic islet cells

Answer 6

1. A-cells (alpha): fine granules: presumed function is glucagon formation.
2. B-cells (beta): coarse granules; more numerous; form insulin.
3. D-cells (delta): secrete somatostatin (used to control insulin/glucagon)

Question 7

Describe and compare the 3 types of hepatic lobule organizations

Answer 7

Classic: central venule is center of lobule. Portal triads are at the angles.

Portal: 3 central venules of adjacent lobules form a triangle. Portions of the bile canaliculi of the 3 lobules drink into the same bile duct.

Liver acinus: includes 3 zones defined by hepatic tissue receiving blood from a branch of the hepatic artery conducting blood to opposite central veins. Metabolic gradient extends from hepatic triad to central vein.

Question 8

Describe the location of and components of the portal triad

Answer 8

Location: found at angles (corners) of classic lobule.

Components:

• branch of hepatic artery (arterioles)
• branch of portal vein (venule)
• bile duct (ductule)

Question 9

Describe the organization of the hepatic lobule, including the space of disse, space of mall, canal of herring, limiting plate, hepatic plates, sinusoid, central venule, and their relationship to the portal triad components

Answer 9

• Space of disse: separates liver cells from endothelial cells. Active transfer btw blood and parenchyma.
• Space of mall: drains into lymphatics.
• Canal of herring: terminal point of the network of bile canalicular trenches found on hepatic surface. Carries bile from canaliculus to bile ductule.
• Limiting plate: surrounds portal space. Branches of vessels and biliary ductules perforate the limiting plate to enter/exit hepatic lobule.
• Hepatic plates:
• Sinusoid:
• Central venule:

Question 10

Describe the cellular details and functions of hepatocytes, kuppfer cells, and perisinusoidal cells

Answer 10

-Hepatocytes:polyhedral, basolateral domain-microvilli in space of disse-absorption of blood-borne substances
Bile canaliculus in apical domain.
-kuppfer cells: phagocitic cell, derived from monocytes, lines hepatic sinusoids.
-Perisinusoidal cells: in space of disse, store vitamin A, produce collagen fiber and extracellular matrix components. This is what makes liver cirrhotic during cirrhosis

Question 11

Describe the afferent and efferent vasculature of the liver, including: portal vein, hepatic artery, ventral vein and sinusoids, and hepatic veins

Answer 11

Afferent blood vessels give off interlobular branches: portal vein and hepatic artery.

Branches from portal vein enter lobule and empty into hepatic sinusoids converge toward the center to empty into the central vein (EFFERENT vessel)

Central veins unite to form a sublobular vein, tributary of the hepatic vein.

Hepatic artery followed the branching of the portal vein through the interlobular CT; interlobular arterioles empty into hepatic sinusoids. Which drain to central vein.

Question 12

Be able to trace arterial, portal and venous blood flow through the liver and hepatic lobule

Answer 12

Fig 17-10 and slide 38

Hepatic artery to the sinusoids to the central vein to hepatic vein

Question 13

Be able to identify on pic hepatic histo

Answer 13

K