Digestive Glands and Liver II

Question 1

Classic organization of Hepatic Lobules

Answer 1

central venule in the center of the lobule; portal triads are at the angles

Question 2

Portal organization of hepatic lobules

Answer 2

3 central venules of adjacent lobules form triangle. Portions of the bile canaliculi of the 3 lobules drain into the same bile duct

Question 3

Liver Acinus organization of hepatic lobules

Answer 3

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

Question 4

Where is the portal triad located?

Answer 4

at angles (corners) of the classic lobule

Question 5

What are the 3 components of the portal triad?

Answer 5

Branch of hepatic artery, branch of portal vein and bile duct

Question 6

Space of Disse

Answer 6

Separates hepatic cells from endothelial cells. Active in transfer b/w blood and parenchyma. Contains types 1,III, and IV collagens.

Question 7

Space of Mall

Answer 7

continuous w/ space of Disse. Drains in to lymphatics.

Question 8

Organization of the hepatic lobule

Answer 8

Epithelial parenchyma is composed of hepatic cells irregularly arranged as plates seen on edges as cell cords and radially arranged around the central vein.

Question 9

Canal of Hering

Answer 9

Receives bile from canaliculus and carries bile to bile ductule.

Question 10

Limiting plate

Answer 10

What the lymphatic vessels peirce through to drain the Space of Mall. They surround the portal space.

Question 11

Hepatic plates

Answer 11

formed by single rows of hepatocytes.

Question 12

Hepatocyte

Answer 12

polyhedral, central nucleus w/ one or more nucleoli. Cytoplasm may contain glycogen, fat droplets, and pigment granules.

Question 13

Kupffer cells

Answer 13

Phagoctytic cell, derived from monocytes. Lines hepatic sinusoids

Question 14

Where are Perisinusoidal cells located?

Answer 14

Space of Disse

Question 15

Function of Perisinusoidal cells

Answer 15

Store vit. A. Produce collagen fibers and extracellular matrix components.

Question 16

What do the perisinusoidal cells do during Cirrhosis?

Answer 16

Transform into myofibroblasts. Become the main collagen type I producing cells - stimulated by cytokines from hepatocytes, Kupffer cells and lymphocytes.

Question 17

What are the two afferent blood vessels in the liver?

Answer 17

portal vein and hepatic artery

Question 18

What is the efferent vessel of the liver?

Answer 18

central vein

Question 19

Functions of the liver

Answer 19

remove bile pigments from the blood and secrete them to bile. store glycogen. convert fats and proteins to carbs. maintain constancy of blood glucose level. chief site of a.a deamination w/ urea byproduct. metabolizing fat and store. synthesize plasma proteins (fibrinogen, prothrombin, and albumin). Store essential vitamins A, D, B2,3,4,12 and K. Serving as an embryonic hematopoietic organ. Ethanol metabolism. Detox of drugs, steroids, vit. A and D, FA, and carcinogens.

Question 20

Ethanol metabolizing pathway

Answer 20

ethanol -> acetaladehyde -> hepatocyte injury v

acetate (w/ acetaldehyde dehydrogenase) in the mito

Question 21

What is the major pigment of bile?

Answer 21

bilirubin

Question 22

Components of bile

Answer 22

Bile acids (cholic and chenodeoxycholic, deoxcycholic and lithocholic acids); water and electrolytes; cholesterol and phospholipids (lecithin); pigments and organic molecules

Question 23

Pathway for production of bile

Answer 23

Hb released from damaged RBS, Hb phagocytized by macrophages and split into globin and Heme. Heme ring is open to free iron - heme is transported in the blood by transferrin forming a straight chain of pyrrole nuclei. Heme is converted by heme oxygenase into biliverdin. Biliberdin -> free (unconjugated) bilirubin.

Question 24

Pathway for secretion of bile (from free bilirubin)

Answer 24

free bilirubin is transported attached to plasma albumin to liver hepatocytes. Free bilirubin is released from plasma ablubin w/i the liver cells and conjugated which is secreted (active transport) into the intestine. Conj. bilirubin in the intestine is converted by bacterial action into urobilinogen.

Question 25

Urobilinogen

Answer 25

oxidized into excreted products or reabsorbed into the blood and carried back to the liver to be re-excreted by the liver or excreted in the urine.

Question 26

3 kinds of conjugated bilirubin

Answer 26

with glucuronic acid -> bilirubin glucuronids
With sulfate -> bilirubin sulfate
w/ a variety of other substances

Question 27

Free (unconjugated) bilirubin

Answer 27

When heme is converted by heme oxygenase into biliverden -> free bilirubin which is attached to plasma albumin.