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GI- Week 6 > Skildum: Liver Biochemistry 2 > Flashcards

Skildum: Liver Biochemistry 2 Flashcards

1
Q

From what and when does the liver synthesize ketone bodies?

A

Ketone bodies are synthesized from FATTY ACIDS during EXTENDED FASTING/ starvation.

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2
Q

Why is it important for the liver to synthesize ketone bodies during periods of extended fasting/starvation?

A

Ketone bodies serve as an ALTERNATIVE FUEL SOURCE to reserve glucose for tissues that are dependent on it, e.g. red blood cells.

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3
Q

How does the liver synthesize nucleotides?

A

Uses blood AA to form purines, pyrimidines, heme, NTs, hormones, and other functional N products.

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4
Q

Why does the liver have a high requirement for products of the PPP?

A

NADPH powers biosynthetic and detoxification reactions.

Nucleotides are used for nucleic acids and cofactors.

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5
Q

What are some proteins that are synthesized in the liver (modified by branched sugar chains)?

A

Blood coagulation proteins
Metal-binding proteins
Lipid transport proteins
Albumin

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6
Q

Where does glycosylation of glycoproteins and proteoglycans occur? What does the chain begin assembly on?

A

Lumen of the endoplasmic reticulum.

a molecule of dolichol

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7
Q

How is the glycosyl chain formed?

A

transferred from dolichol to the protein>

modified further as it is transferred through the Golgi

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8
Q 
Hepatopathy
Bifid uvula
Growth retardation
Myopathy
Hypoglycemia
Dilated cardiomyopathy

Are associated w/ what gene mutation?

A

homozygous PGM1 mutations

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9
Q

What does PGM1 do?

A

interconverts glucose 1-phosphate and glucose 6-phosphate

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10
Q

What is PGM1 essential for?

A

glycogenolysis
glyocogen synthesis.
important for generating UDP-galactose, a glycosylation intermediate.

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11
Q

What does transferrin do?

A

Transports ferric iron (Fe3+) from the intestine to the liver.

*glycosylated at 2 sites

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12
Q

Pts w/ PGM1 muts have defects in what type of glycosylation?

A

transferrin glycosylation

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13
Q

What supplement can increase the glycosylation of transferrin?

A

galactose supplementation

also helps to resolve sxs of:
Rhabdomyolysis resolved & cardiac function improved
Hypogonadotropic hypogonadism resolved
Leuteneizing hormone increased
Puberty initiated
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14
Q

Why is glycosylation of leutenizing hormone (LH) important?

A

It stabilizes it in circulation and increases its affinity for its receptor

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15
Q

What detects liver damage?

A

increase in conjugated + unconjugated serum bilirubin

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16
Q

What detects hemolysis?

A

increase in unconjugated serum bilirubin

17
Q

What lab may indicate urea cycle problems?

A

serum ammonia

18
Q

What can an elevated bilirubin indicate?

A

increased red cell breakdown or decreased conjugating capacity in the liver

19
Q

What is the difference between direct and indirect bilirubin?

A

conjugated vs unconjugated

20
Q

BIlirubin is glycosylated in the liver by adding UDP glucuronate to form bilirubin diglucuronide. What catalyzes this reaction?

A

glucuronosyl transferase

21
Q

Why is it important to form bilirubin diglucuronide?

A

more soluble and can be excreted in the bile or urine

22
Q

What is the rate limiting step in bilirubin elimination?

A

transport across the canilicular membrane

23
Q

What enzyme test is the most specific for liver damage?

A

ALT

24
Q

AST:ALT <1 suggests…..

A

ACUTE hepatocellular damage

25
Q

AST:ALT >2 suggests…

A

Liver damage secondary to alcohol abuse

26
Q

What enzyme tests detect cholestasis (bile duct blockage)?

A

alkaline phosphatase

5’ nucleotidase

gamma-glutamyltranspeptidase

27
Q

Where is alkaline phosphatase located?

A

localized to canilicular membrane of hepatocytes

NOT specific for cholestasis (or liver disease)

28
Q

Where is 5’ nucleotidase located?

A

localize to canilicular membrane of hepatocytes

29
Q

Where is gamma-glutamyltranspeptidase located?

A

localized in bile duct epithelial cells

30
Q

What tests measure the liver’s biosynthetic capacity (proteins made by the liver)?

A

Serum albumin

serum globulins

coagulation cofactors

31
Q

What liver protein has a long half life (so it is not good for acute liver damage) and if
decreased may reflect malnutrition rather than liver disease?

A

Serum albumin

32
Q

What produces serum globulins?

A

B lymphocytes (gamma-globulin) and hepatocytes (alpha and beta globulins)

33
Q

Why do gamma globulins increase w/ liver disease?

A

increased antigenic material circulating in the hepatic circulation

34
Q

What is indicative of alcoholic liver disease?

A

increased IgA

35
Q

What liver disease is indicated by increased IgG?

A

Autoimmune hepatitis

36
Q

What liver disease is indicated by increased IgM?

A

primary biliary cirrhosis

37
Q

An elevated pTT suggests ….

A

defect in synthesizing fibrinogen in the liver

GI- Week 6 (14 decks)

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