CC LAB > Liver Function Test > Flashcards

Liver Function Test Flashcards

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1
Q

What is the approximate weight of the liver?

A

1.2–1.5 kg

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2
Q

How many lobes does the liver have and what divides them?

A

Two lobes, divided by the falciform ligament

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3
Q

Where is the liver located?

A

Beneath the diaphragm

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4
Q

How much blood flows through the liver per minute?

A

Approximately 1500 mL per minute

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5
Q

From where does the liver receive most of its blood and nutrients?

A

From the Gastrointestinal Tract (GIT) via the portal vein

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6
Q

What is the main function of the liver regarding nutrients from the GIT?

A

Converts nutrients from diet into usable or storage forms

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7
Q

What are the microscopic functional units of the liver called?

A

Lobules

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8
Q

What cells make up the lobules and perform most liver functions?

A

Parenchymal cells (hepatocytes)

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9
Q

What do hepatocytes produce?

A

Bile, bilirubin, and plasma proteins

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10
Q

Around what structures are hepatocytes arranged?

A

Around portal triads and a central vein

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11
Q

What are sinusoidal membranes?

A

Sites where nutrients from the GIT diffuse into hepatocytes for metabolism.

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12
Q

What is the function of lymphatic vessels in the liver?

A

Remove excess fluid from the liver.

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13
Q

What is the function of biliary canaliculi?

A

Carry bile out of the liver into the common bile duct.

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14
Q

What are Kupffer cells?

A

Specialized macrophages that remove debris and old RBCs from the blood.

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15
Q

Function of the smooth endoplasmic reticulum (SER) in hepatocytes

A

Site of drug detoxification, bilirubin conjugation, and cholesterol synthesis

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16
Q

Function of the rough endoplasmic reticulum (RER)?

A

Protein synthesis (including enzymes and coagulation factors)

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17
Q

Function of the Golgi complex?

A

Modifies proteins by attaching carbohydrates and lipids, forming glycoproteins and lipoproteins

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18
Q

Function of mitochondria in hepatocytes?

A

Perform oxidative phosphorylation and fatty acid oxidation

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19
Q

Function of lysosomes?

A

Responsible for protein breakdown

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20
Q

Function of microtubules and microfilaments?

A

Maintain hepatocyte structure

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21
Q

What are the four major liver functions?

A
  1. Synthetic function
    1. Excretory and secretory function
    2. Detoxification and drug metabolism
    3. Storage function
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22
Q

What are the liver’s roles in carbohydrate metabolism?

A

• Glycogenolysis – breakdown of glycogen
• Glycogenesis – synthesis of glycogen
• Gluconeogenesis – formation of glucose from non-carbohydrate sources

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23
Q

What are the liver’s roles in lipid metabolism?

A

• Processes triacylglycerol (TAG), phospholipids, and cholesterol
• Converts fatty acids to Acetyl-CoA
• Synthesizes and transports lipoproteins

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24
Q

What are the liver’s roles in protein metabolism?

A

Synthesizes all plasma proteins except hemoglobin and immunoglobulins

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25
What is meant by the “First Pass” effect of the liver?
It refers to the liver’s role as a “gatekeeper” where every substance absorbed from the GIT first passes through the liver before entering systemic circulation.
26
What happens to drugs or foreign materials during detoxification?
• They are inactivated by binding or chemical modification. • The liver converts them into excretable forms.
27
What are the main detoxification reactions performed by the liver?
• Carboxylation • Oxidation • Reduction • Hydrolysis • Hydroxylation • Demethylation
28
What is bilirubin?
A yellow-orange pigment formed from the breakdown of heme in aging red blood cells.
29
Where is bilirubin metabolized and excreted?
• Metabolized: in the liver • Excreted: in bile and urine
30
Who discovered bilirubin and what was it first called?
Discovered by Rudolf Virchow (1849) — called Hematoidin Renamed “Bilirubin” by Stadeler (1864)
31
What are the two main types of bilirubin?
1. Unconjugated (Indirect, Bilirubin I) 2. Conjugated (Direct, Bilirubin II or Bilirubin diglucuronide)
32
Describe Unconjugated (Indirect) Bilirubin:
• Found in plasma • Water-insoluble • Bound to albumin • Reacts with Diazo reagent only in the presence of an accelerator
33
Describe Conjugated (Direct) Bilirubin:
• Found in serum • Water-soluble • Reacts with Diazo reagent without an accelerator
34
What is the principle of the Malloy–Evelyn method?
Bilirubin reacts with Diazo reagent forming red-purple azobilirubin measured at 560 nm.
35
What are the key features of the Malloy–Evelyn method?
• pH = 1.2 • Accelerator: 50% methanol
36
What is the principle of the Jendrassik–Grof method?
Bilirubin reacts with diazo reagen (sulfanilic acid in hydrochloric acid and sodium nitrite) to form purple azobilirubin, measured at 598–600 nm.
37
What are the key reagents in the Jendrassik–Grof method?
* Diazo reagent: Sulfanilic acid + HCl + Sodium nitrite * Aliqout 1: react with diazo reagent * Aliqout 2: diazo + accelerator (caffeine-benzoate) * Ascorbic acid: Stops the diazo reaction (removes excess reagent) * Alkaline tartrate solution: Shifts absorbance to reduce interference and turn color intense blue
38
What are the advantages of the Jendrassik–Grof method?
1. Not affected by pH changes 2. Unaffected by protein concentration variations 3. Stable optical sensitivity at low bilirubin levels 4. Produces minimal turbidity 5. Not affected by hemoglobin up to 750 mg/dL
39
Name the major liver enzymes used in LFTs.
• Transaminases: ALT (Alanine aminotransferase), AST (Aspartate aminotransferase) • Alkaline phosphatase (ALP) • Lactate dehydrogenase (LDH) • γ-Glutamyl transferase (GGT) • 5’-Nucleotidase (5’-NT)
40
What other tests can assess liver function aside from enzymes?
• Serum proteins (especially albumin) • Coagulation tests: PT (Prothrombin Time) and APTT (Activated Partial Thromboplastin Time)
41
What specimen types are used for bilirubin and liver enzyme testing?
Serum or plasma
42
What conditions should be avoided during specimen handling?
• Hemolysis (releases RBC pigments) • Light exposure (bilirubin is light-sensitive)
43
What conditions should be avoided during specimen handling?
Because bilirubin degrades when exposed to light, causing falsely low results.
44
What is jaundice (icterus)?
A condition characterized by increased bilirubin in the blood (hyperbilirubinemia), leading to yellow discoloration of the skin, mucous membranes, and sclera.
45
What is the origin of the term “jaundice”?
It comes from the French word “jaune,” meaning yellow.
46
What causes pre-hepatic hyperbilirubinemia?
Increased bilirubin production due to excessive RBC destruction (hemolysis
47
Examples of conditions causing pre-hepatic jaundice:
• Acute or chronic hemolytic anemia • Malaria
48
What type of bilirubin is increased in pre-hepatic jaundice?
Unconjugated (indirect) bilirubin
49
Is bilirubin seen in urine in pre-hepatic jaundice?
No, because unconjugated bilirubin is not water-soluble and is bound to albumin.
50
What causes hepatic jaundice?
Defective uptake, conjugation, or excretion of bilirubin by damaged hepatocytes.
51
What are examples of disorders causing unconjugated hyperbilirubinemia?
• Gilbert Syndrome • Crigler Najjar Syndrome • Physiologic Jaundice of the Newborn • Lucey–Driscoll Syndrome
52
Gilbert Syndrome
mild deficiency in glucuronyl transferase
53
Crigler–Najjar Syndrome
severe deficiency or absence of glucuronyl transferase
54
Physiologic Jaundice of the Newborn
immature liver enzyme system
55
transient enzyme inhibition in newborns
Lucey–Driscoll Syndrome
56
What are examples of disorders causing conjugated
• Dubin–Johnson Syndrome • Rotor Syndrome
57
defective excretion of conjugated bilirubin due to transport defect
Dubin–Johnson Syndrome
58
similar to Dubin–Johnson but no liver pigmentation
Rotor Syndrome
59
What causes post-hepatic jaundice?
Obstruction of bile flow from the biliary tract.
60
What are common causes of obstructive jaundice?
• Biliary obstruction disease (e.g., gallstones, tumors, strictures) • Cholestasis
61
What type of bilirubin increases in post-hepatic jaundice?
Conjugated (direct) bilirubin (B2)
62
What happens to red blood cells after 120–126 days?
They are eaten by macrophages, leading to the breakdown of hemoglobin into iron, globin, and protoporphyrin IX.
63
What happens to iron released from RBCs during breakdown?
Iron binds to transferrin and is sent to the bone marrow or liver for storage or reuse.
64
What happens to globin after RBC breakdown?
Globin is reused by the body after being broken down into amino acids.
65
What enzyme converts protoporphyrin IX to biliverdin?
Heme oxygenase (occurs in the lungs).
66
What is formed when protoporphyrin IX is broken down by heme oxygenase?
Biliverdin, carbon monoxide (CO), and iron.
67
How long after RBC destruction does bilirubin appear?
Biliverdin converts to bilirubin after about 2–3 hours.
68
What is B1 bilirubin?
Unconjugated bilirubin — water-insoluble, bound to albumin, and carried to the liver.
69
What protein carries unconjugated bilirubin (B1) to the endoplasmic reticulum in the liver?
Ligandin
70
What enzyme conjugates bilirubin in the liver?
Uridyl Diphosphate Glucuronyl Transferase (UDP-GT).
71
What cofactor provides glucuronic acid during bilirubin conjugation?
Uridyl Diphosphate (UDP)
72
What is the product of bilirubin conjugation?
B2 or Bilirubin Diglucuronide — conjugated, water-soluble bilirubin.
73
Where is conjugated bilirubin (B2) secreted after formation in the liver?
Into bile canaliculi → gallbladder → bile duct → small intestine.
74
What converts bilirubin in the intestine into mesobilirubin and mesobilirubinogen?
Anaerobic bacteria.
75
What are the intermediate products of bilirubin breakdown in the intestines?
Mesobilirubin → Mesobilirubinogen → Stercobilinogen and Urobilinogen.
76
What percentage of urobilinogen is reabsorbed into the liver?
20%.
77
What percentage of urobilinogen is excreted into stool?
80%.
78
What happens to reabsorbed urobilinogen that reaches circulation?
It’s filtered by the kidneys and excreted in urine as Urobilin (yellow pigment).
79
What gives stool its brown color?
Stercobilin (oxidized urobilinogen)
80
Summarize the bilirubin pathway from RBC breakdown to excretion.
RBC → Heme → Biliverdin → Bilirubin (B1, albumin-bound) → Liver (Ligandin + UDP-GT + Glucuronic acid → B2) → Bile → Intestine → Mesobilirubin → Urobilinogen → 20% urine (Urobilin), 80% stool (Stercobilin).
81
What happens to red blood cells after 120–126 days?
They are eaten by macrophages, leading to the breakdown of hemoglobin into iron, globin, and protoporphyrin IX.
82
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