Skildum: Liver Biochemistry 2 Flashcards Preview

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

Flashcards in Skildum: Liver Biochemistry 2 Deck (37):
1

From what and when does the liver synthesize ketone bodies?

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

2

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

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

3

How does the liver synthesize nucleotides?

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

4

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

NADPH powers biosynthetic and detoxification reactions.

Nucleotides are used for nucleic acids and cofactors.

5

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

Blood coagulation proteins
Metal-binding proteins
Lipid transport proteins
Albumin

6

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

Lumen of the endoplasmic reticulum.

a molecule of dolichol

7

How is the glycosyl chain formed?

transferred from dolichol to the protein>
modified further as it is transferred through the Golgi

8

Hepatopathy
Bifid uvula
Growth retardation
Myopathy
Hypoglycemia
Dilated cardiomyopathy

Are associated w/ what gene mutation?

homozygous PGM1 mutations

9

What does PGM1 do?

interconverts glucose 1-phosphate and glucose 6-phosphate

10

What is PGM1 essential for?

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

11

What does transferrin do?

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

*glycosylated at 2 sites

12

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

transferrin glycosylation

13

What supplement can increase the glycosylation of transferrin?

galactose supplementation

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

14

Why is glycosylation of leutenizing hormone (LH) important?

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

15

What detects liver damage?

increase in conjugated + unconjugated serum bilirubin

16

What detects hemolysis?

increase in unconjugated serum bilirubin

17

What lab may indicate urea cycle problems?

serum ammonia

18

What can an elevated bilirubin indicate?

increased red cell breakdown or decreased conjugating capacity in the liver

19

What is the difference between direct and indirect bilirubin?

conjugated vs unconjugated

20

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

glucuronosyl transferase

21

Why is it important to form bilirubin diglucuronide?

more soluble and can be excreted in the bile or urine

22

What is the rate limiting step in bilirubin elimination?

transport across the canilicular membrane

23

What enzyme test is the most specific for liver damage?

ALT

24

AST:ALT <1 suggests.....

ACUTE hepatocellular damage

25

AST:ALT >2 suggests...

Liver damage secondary to alcohol abuse

26

What enzyme tests detect cholestasis (bile duct blockage)?

alkaline phosphatase

5' nucleotidase

gamma-glutamyltranspeptidase

27

Where is alkaline phosphatase located?

localized to canilicular membrane of hepatocytes

NOT specific for cholestasis (or liver disease)

28

Where is 5' nucleotidase located?

localize to canilicular membrane of hepatocytes

29

Where is gamma-glutamyltranspeptidase located?

localized in bile duct epithelial cells

30

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

Serum albumin

serum globulins

coagulation cofactors

31

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?

Serum albumin

32

What produces serum globulins?

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

33

Why do gamma globulins increase w/ liver disease?

increased antigenic material circulating in the hepatic circulation

34

What is indicative of alcoholic liver disease?

increased IgA

35

What liver disease is indicated by increased IgG?

Autoimmune hepatitis

36

What liver disease is indicated by increased IgM?

primary biliary cirrhosis

37

An elevated pTT suggests ....

defect in synthesizing fibrinogen in the liver