(F) L3: Liver Function Tests (Introduction)

Question 1

Which liver lobe is larger than the other?

Answer 1

Right

Question 1

• A large organ that weighs 1.2 to 1.5 kg in a healthy adult
• The chief metabolic organ that metabolizes nutrients and detoxifies blood
• Located at the right upper quadrant of the abdomen, beneath and attached to the diaphragm
• Has a right and left lobe divided by the falciform ligament

Answer 1

Liver

Question 2

• This is located near the liver where it is connected via the common bile duct
• Waste products from the liver, bile salts, bile acids, and bilirubin go into this organ
• This is responsible for the storage of bile

Answer 2

Gallbladder

Question 3

The liver’s blood supply comes from what 2 blood vessels?

Also give the percentages of how much blood they supply

Answer 3

1. Hepatic artery (25%; oxygenated)
2. Portal vein (75%; rich in nutrients)

Question 4

The liver receives how many mL of blood per minute?

Answer 4

15mL

Question 5

Once the hepatic artery and portal veins reach the hepatic sinusoids, where does the blood go in order to return to the general circulation?

Answer 5

Central canal

Question 6

Toxins that were removed from the blood will be excreted via what passage to the gallbladder?

(2 answers)

Answer 6

Bile canal and bile duct

Note: The waste products will go into the feces

Question 7

This liver cell type is responsible for the metabolism and synthesis of proteins

Answer 7

Hepatocytes

Question 8

This liver cell type is a macrophage which are important for phagocytosis (for immunity)

Answer 8

Kupffer Cells

Question 9

Functions of the Liver

Carbohydrates are stored in the liver in the form of glycogen and vitamins

Answer 9

Storage

Question 10

Functions of the Liver

• Refers to the processing of carbohydrates, lipids, and proteins
• Important for the processes of glycogenesis, glycogenolysis, and gluconeogenesis

Answer 10

Metabolism

Question 11

Functions of the Liver

Most plasma proteins and clotting factors are produced by the liver hence why the proteins will decrease in number whenever there is liver damage

Answer 11

Synthetic

Question 12

Functions of the Liver

• Transamination leads to the production of ketoacids (Kreb’s cycle) and ammonia (Urea cycle)
• Important for the removal of toxic substances such as alcohol, drugs, and ammonia to urea

Answer 12

Detoxification

Question 13

Functions of the Liver

• Has something to do with the biliary system (bilirubin and bile)
• Bilirubin (B1: originally unconjugated) will be coupled to a protein to make it conjugated (B2)

Answer 13

Conjugation/ Excretory and Secretory

Question 14

Excretory and Secretory Function

• aka GALL, a dark green or yellowish brown fluid
• Produced by the liver, stored in the gallbladder, and released in the duodenum
• Helps in lipid digestion, emulsification of dietary lipids, and hydrolysis of TAGs
• Is composed of water, fatty acids, cholesterol, bile acids/salts, and bilirubin

Answer 14

Bile

Question 15

Excretory and Secretory Function

Bile acid vs. Bile salt:
1. The unconjugated form
2. The conjugated form

Answer 15

1. Unconjugated - Bile acid
2. Conjugated - Bile salt

Note: Salts are also acids but only conjugated with amino acids

Question 16

Excretory and Secretory Function

These are waste products of cholesterol metabolism which are the primary components of bile that facilitate the digestion and absorption of lipids

Answer 16

Bile acids/Bile salts

Question 17

Classification of Bile Acids and Bile Salts

Primary or Secondary?
1. Cholic acid and Chenodeoxycholic acid
2. Deoxycholic acid, Lithocholic acid, and Ursodeoxycholic acid

Answer 17

1. Primary
2. Secondary

Question 18

Classification of Bile Acids and Bile Salts

Primary or Secondary?
Not yet exposed to the normal flora of the intestines which utilize these bile acids/salts

Answer 18

Primary

Question 19

Classification of Bile Acids and Bile Salts

Primary or Secondary?
Already exposed to the normal flora of the intestines

Answer 19

Secondary

Question 20

Classification of Bile Acids and Bile Salts

The primary and secondary classification in the lab is used to differentiate between what 2 conditions?

Answer 20

Biliary Obstruction and Liver Cirrhosis

Question 21

Classification of Bile Acids and Bile Salts

What condition?
Increased ratio of primary and secondary bile salts/acids

Answer 21

Biliary Obstruction

Question 22

Classification of Bile Acids and Bile Salts

What condition?
Decreased ratio of primary and secondary bile salts/acids

Answer 22

Liver Cirrhosis

Question 23

Excretory and Secretory Function

• A pigment that imparts a yellow color to the bile (different from biliverdin which is green)
• Approximately 200-300mg of this is produced per day
• A metabolic waste product of heme breakdown (80% from RBCs)
• Can be used to assess the conjugation and excretion function of the liver

Answer 23

Bilirubin

Question 24

# Excretory and Secretory Function What type of bilirubin is found in the bile?

Answer 24

Conjugated (B2)

Question 25

# Excretory and Secretory Function Bilirubin must be excreted from the body in what form?

Answer 25

Urobilinogen (therefore if bilirubin is elevated, there must be a problem with the liver)

Question 26

# Bilirubin Synthesis Pathway Step 1: Heme is converted into what using the heme oxygenase enzyme?

Answer 26

Biliverdin

Question 27

# Bilirubin Synthesis Pathway Step 2: Biliverdin is converted into what with the help of biliverdin reductase?

Answer 27

Unconjugated Bilirubin (B1)

Question 28

# Bilirubin Synthesis Pathway - This is water insoluble - Is aka "pre-hepatic, indirectly measured, and slow reacting" bilirubin

Answer 28

Unconjugated Bilirubin (B1)

Question 29

# Bilirubin Synthesis Pathway Step 3: Unconjugated Bilirubin (B1) needs a transport protein to reach the liver (since it is water insoluble) which is what?

Answer 29

Albumin

Question 30

# Bilirubin Synthesis Pathway Step 4: Once B1 enters the hepatocytes, it will bind to what proteins before going to the smooth endoplasmic reticulum? (3 answers)

Answer 30

1. Y proteins 2. Z proteins 3. Ligandin

Question 31

# Bilirubin Synthesis Pathway In what hepatocyte organelle does bilirubin conjugation occur in?

Answer 31

Smooth ER

Question 32

# Bilirubin Synthesis Pathway Step 5: This enzyme helps in the conjugation of B1 into B2, what is it?

Answer 32

Uridylphosphate Glucuronyl Transferase (UDPGT) | Note: It adds 2 glucuronic acids to B1

Question 33

# Bilirubin Synthesis Pathway - This is water soluble - Is aka "directly measured and prompt reacting" bilirubin

Answer 33

Conjugated Bilirubin (B2)

Question 34

# Bilirubin Synthesis Pathway What is the other name for B2 with respect to the addition of 2 glucuronic acids?

Answer 34

Diconjugated/Diglucuronide Bilirubin

Question 35

# Bilirubin Synthesis Pathway If there is biliary obstruction, what can we expect with the levels of B1 and B2?

Answer 35

B1 is normal while B2 is elevated

Question 36

# Bilirubin Synthesis Pathway Step 6: Once bile is released to this organ, it will aid in the digestion and emulsification of fats

Answer 36

Intestines

Question 37

# Bilirubin Synthesis Pathway Step 7: Once B2 encounters the normal flora found in the GIT, it will be converted to what?

Answer 37

Urobilinogen

Question 38

# Bilirubin Synthesis Pathway Step 8: Approximately 80% of urobilinogen is excreted where in the form of urobilin/stercobilin?

Answer 38

Feces

Question 39

# Bilirubin Synthesis Pathway TOF: Urobilinogen is originally colorless but will produce color once reduced (yellow for urobilin and brown for stercobilin)

Answer 39

False (oxidized, not reduced)

Question 40

# Bilirubin Synthesis Pathway This manifestation of biliary obstruction refers to when one's stool is colorless due to decreased urobilinogen

Answer 40

Steatorrhea

Question 41

# Bilirubin Synthesis Pathway Step 8: The remaining 20% of urobilinogen is recirculated into what cycle?

Answer 41

Extrahepatic/Enterohepatic Cycle

Question 42

# Bilirubin Synthesis Pathway Step 9: A small portion of the 20% recycled bilirubin will enter the systemic circulation which will be excreted at a rate of 1-4mg a day in what specimen?

Answer 42

Urine

Question 43

# HPLC Bilirubin Fractions The unconjugated bilirubin (B1)

Answer 43

Alpha-bilirubin

Question 44

# HPLC Bilirubin Fractions The monoglucuronide/monoconjugated bilirubin

Answer 44

Beta-bilirubin

Question 45

# HPLC Bilirubin Fractions The diglucuronide/diconjugated bilirubin (B2)

Answer 45

Gamma-bilirubin

Question 46

# HPLC Bilirubin Fractions - A conjugated form that is irreversibly bound to albumin (biliprotein) - Formed when there is prolonged elevation of conjugated bilirubin in biliary obstruction

Answer 46

Delta-bilirubin

Question 47

# HPLC Bilirubin Fractions This formula gives what product? Total Bilirubin - (Direct Bilirubin [B2] + Indirect Bilirubin [B1])

Answer 47

Delta-bilirubin