Gastro 12 - Liver Basics

Question 1

What structure does the liver arise from?

Answer 1

The Hepatic diverticulum: grows off of the anterior part of the distal foregut. Becomes the liver, biliary system, and head of pancreas.

Question 2

Where is the major site of hematopoiesis in embryos and why?

Answer 2

Liver is the major site. Mesodermal hematopoietic stem cells migrate from the mesonephros to the liver at about 3 weeks till about week 28 when bone marrow gets going.

Question 3

What are the two sources of blood in the liver and where do they come from? Where do they all drain?

Answer 3

Branch of the hepatic artery, bringing blood rich in O2. Branch of portal vein that’s just been drained from the GI tract (Mesenteric vein and gastric vein). They empty into the central vein.

Question 4

What are the components of a portal triad?

Answer 4

Branch of the Hepatic artery. Branch of the Portal vein. Bile ductile.

Question 5

What are the zones of the lobules of the liver?

Answer 5

Zone 1, 2, and 3. Zone 1 is closet to the portal triad and most affected by viral hepatitis. Zone 3 is farthest from portal triad and closest to central vein, and sensitive to hypotension and ischemia and toxic substances.

Question 6

How is the blood flow in a liver lobule? The bile flow?

Answer 6

The blood flows from the portal triad to the central vein (Zone 1 to zone 3) while bile flows the opposite way to reach the bile ductule.

Question 7

What are the four main functions of hepatocytes?

Answer 7

Make proteins. Metabolize toxins and drugs. Storage. Make bile and excrete bilirubin.

Question 8

What proteins do the hepatocytes make?

Answer 8

Coagulation factors. Complement proteins. Albumin. Apolipoproteins. C-reactive proteins. Angiotensinogen. Transferrin. Ceruloplasmin.

Question 9

What enzymes does the hepatocytes make for mteabolization of toxins and drugs?

Answer 9

Cytochrome P450 enzymes. UDP-glucuronyl transferase. ALT and AST. Steroid hormones are turned into inactive metabolites.

Question 10

What do hepatocytes store?

Answer 10

Glucose as glycogen. Cholesterol and triglycerides (VLDL particles). Minerals (iron). Vitamins (B12, fat-soluble).

Question 11

Where does bilirubin come from?

Answer 11

Breakdown of heme from hemoglobin. Heme is converted to biliverdin and then to bilirubin.

Question 12

Bilirubin is insoluble. How does it travel to the liver?

Answer 12

By albumin.

Question 13

What does UDP-glucuronyl transferase do?

Answer 13

Transfers a glucuronyl group on to the bilirubin; this is called conjugation of bilirubin, a conjugated bilirubin.

Question 14

Why are newborns susceptible to physiologic jaundice?

Answer 14

Have a reduced amount of UDP-GT.

Question 15

What happens when there is too much unconjugated bilirubin In newborn?

Answer 15

Kernicterus: causes chroea, gaze abnormalities, cerebral palsy, hearing loss.

Question 16

How do we treat hyperbilirubinemia?

Answer 16

Phototherapy.

Question 17

What are the four hereditary hyperbilirubinemia disorders?

Answer 17

Gibert. Crigler-Najjar. Dubin-Johnson. Rotor.

Question 18

What is Gilbert syndrome?

Answer 18

An Autosomal recessive, it is a hereditary hiperbilirubinemia. Due to a mutation in the promotor region of the UDP-GT gene, causing UDP-GT shortage. This causes slowing of bilirubin conjugation, causing slight elevation of indirect bilirubin. It is benign.

Question 19

What is Crigler-Niggar syndrome Type I?

Answer 19

A hereditary hiperbilirubinemia. Has complete absence of UDP-GT. Unable to conjugate bilirubin. Causes jaundive and increase in indirect bilirubin, leading to kernicterus.

Question 20

What are the treatments for Crigler-Nijjar type I?

Answer 20

Phototherapy. Plasmapheresis. Liver transplant is definitive.

Question 21

What is Criggler-Najjar syndrome type II?

Answer 21

A hereditary hiperbilirubinemia. Produces mutated UDP-GT. The degree of hyperbilirubinemia is less than type I.

Question 22

How do we differentiate b/w Type I vs Type II Crigler-Naggar syndrome?

Answer 22

Give phenobarbital; it induces production of hepatic enzymes, including UDP-GT. If type II, it ramps up the liver to make UDP-GT and bilirubin decreases. There will not be a change in bilirubin in type I.

Question 23

What is Dubin-Johnson syndrome?

Answer 23

A hereditary hiperbilirubinemia. It causes trouble in putting conjugated bilirubin into the bile; it stays trapped in hepatocytes. Turns liver black. Causes increase in DIRECT bilirubin. Conjugated and direct bilirubin are the same.

Question 24

What is Rotor syndrome?

Answer 24

A hereditary hiperbilirubinemia. Similar but milder to Dubin-Johnson.

Question 25

From which embryonic layer is the liver derived?

Answer 25

Endoderm.

Question 26

What enzyme is responsible for the conjugation of bilirubin?

Answer 26

UDP glucuronyl transferase.

Question 27

Which hereditary hiperbilirubinemia causes Mildly decreased UDPGT?

Answer 27

Gilbert syndrome.

Question 28

Which hereditary hiperbilirubinemia causes Complete absent UDPGT?

Answer 28

Crigler-Najjar syndrome type I.

Question 29

Which hereditary hiperbilirubinemia causes grossly black liver?

Answer 29

Dubin-Johnson syndrome.

Question 30

Which hereditary hiperbilirubinemia responds to phenobarbital?

Answer 30

Crigler-Najjar syndrome Type II.

Question 31

Which hereditary hiperbilirubinemia includes treatment by plasmapheresis and phototherapy?

Answer 31

Criggler-Najjar type I.

Question 32

Which hereditary hiperbilirubinemia is asymptomatic unless under physical stress (alcohol, infection)?

Answer 32

Gilbert syndrome.

Question 33

RFF: Severe hyperbilirubinemia in a neonate.

Answer 33

Crigler-Najjar Type I.

Question 34

RFF: Mild, benign hyperbilirubinemia.

Answer 34

Gilbert syndrome.