GI module 4

Question 1

The functional unit of the liver is a hexagonal arrangement. Describe the parts of this.

Answer 1

1. hexagonal hepatocytes and microvasculature
2. central vein at center of hexagon
3. At each corner is a portal triad

Question 2

What does the microvasculature of the hepatocyte contain?

Answer 2

sinusoid and bile canaliculi

Question 3

Name the parts of the portal triad

Answer 3

Terminal branch of the hepatic artery
Terminal branch of the portal vein
Terminal bile duct

Question 4

Describe the pathway of bile

Answer 4

Bile canaliculi drain into terminal bile ducts
Terminal bile ducts drain into R/L hepatic ducts
R/L hepatic ducts merge to form common hepatic duct
Common hepatic “divides” into cystic (gallbladder) and common bile which merges with the pancreatic duct to drain into the duodenum

Question 5

T/F liver has the ability to regenerate?

Answer 5

T

Question 6

What are some of the signaling mechanisms that stimulate liver regeneration?

Answer 6

TGF, HGF, EGF

Question 7

If 50-60% of the liver is damaged from 4 days of acetaminophen how long will it take for the liver to completely regenerate?

Answer 7

within 30 days.

Question 8

What are the 2 afferent pathways to the liver and what percent do each supply?

Answer 8

Portal pathway (hepatic portal vein) 75%
Arterial pathway (hepatic artery) 25%

Question 9

What does the portal pathway primarily supply?

Answer 9

nutrients

Question 10

What does the arterial pathway primarily supply?

Answer 10

O2

Question 11

If there is congestion in the portal vein what levels will increase?

Answer 11

02

Question 12

What structures make up the efferent pathway of the liver?

Answer 12

Central veins

Hepatic veins

Question 13

Where do the central veins drain into?

Answer 13

hepatic veins

Question 14

Where do the hepatic veins drain in to?

Answer 14

IVC

Question 15

t/f the liver produces a large amount of lymph?

Answer 15

T

Question 16

The hepatic portal vein receives blood from?

Answer 16

The GI tract, spleen and pancreas

Question 17

What does the hepatic portal vein carry?

Answer 17

A large amount of nutrients from the GI tract, and a relatively small amount of O2

Question 18

Where does the hepatic portal vein terminate?

Answer 18

Divides into R/L branches and further divides until it finally delivers blood to portal vein

Question 19

What collateral veins are part of the hepatic portal anastomosis?

Answer 19

Gastroesophageal v.
Rectal v.
Paraumbilical v.
Portorenal v.

Question 20

When congestion d/t cirrhosis is present what may also be seen on inspection?

Answer 20

Distention of the hepatic portal anastomosis veins

Question 21

Where does the hepatic artery originate from?

Answer 21

The celiac trunk

Question 22

Is blood flow from the hepatic artery impaired during cirrhosis?

Answer 22

NO.

Question 23

What acts as a “capillary bed” for hepatocytes?

Answer 23

Sinusoid

Question 24

What 2 vessels do the sinusoid receive blood from?

Answer 24

Terminal branches of hepatic portal veins, and artery

Question 25

What works to expose hepatocytes to hepatic blood flow?

Answer 25

sinusoids

Question 26

Where does the sinusoid drain into?

Answer 26

Central vein

Question 27

Where are Kupffer cells located?

Answer 27

Surface of the endothelium

Question 28

What do Kupffer cells function to do?

Answer 28

Phagocytic removal of immune complex RBC degradation-remove damaged RBC's SERVES AS EARLY FRONT LIKE DEFENSE AGAINST LIVER DAMAGE

Question 29

What structure allows nutrients/lipids to travel through the sinusoidal wall and flow to microvilli of hepatocyte?

Answer 29

Fenestrated endothelium

Question 30

Where are the stellate cells located?

Answer 30

Space of Disse

Question 31

What is the function of stellate cells?

Answer 31

Store vitamin A | Produce/secrete hepatic factors (liver regen)

Question 32

What pathological relationship do stellate cells have?

Answer 32

Role in fibrosis!! If disrupted transforms into fibroblastic and myoblastic function

Question 33

What are Pit cells aka?

Answer 33

Granular lymphocytes, or NK natural killer cells

Question 34

Where are Pit cells located?

Answer 34

surface of endothelium

Question 35

What is the function of Pit cells?

Answer 35

front like immune defense, attacks tumor/virus | Liver regen.

Question 36

What organ produces the largest amount of lymph fluid in the body?

Answer 36

the liver

Question 37

T/f approximately 10% of lymph fluid is produced in the liver?

Answer 37

F 20% (a huge number relatively)

Question 38

What are the 2 regional zones of hepatocytes in the lobule?

Answer 38

periportal hepatocytes | Centrilobular hepatocytes

Question 39

What is the major difference between periportal and centrilobular hepatocytes?

Answer 39

Perioportal are the "oldest kid" They get all the stuff-first to receive blood therefore are O2 and nutrient rich. Centrilobular are not as exposed and are last to receive blood and have less O2.

Question 40

Which lobular zone is more likely to be damaged by ischemia (or first to be damaged?)

Answer 40

centrilobular

Question 41

What are the primary physiological roles of the liver?

Answer 41

Drug metabolism/biotransformation Metabolism Storage endocrine

Question 42

In what ways is the liver involved in carbohydrate metabolism?

Answer 42

Regulates blood glucose Storage of glucose for future energy needs Gluconeogenesis

Question 43

What is the rate limiting step in gluconeogenesis?

Answer 43

The amount of substrate (NOT liver enzymes)