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Biochem > liver metabolism > Flashcards

liver metabolism Flashcards

1
Q

heme catabolism

A

increased bilirubin

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2
Q

carbohydrate metabolism

A

increased glucose

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3
Q

protein synthesis

A

increased albumin

increased prothrombin time

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4
Q

protein catabolism

A

increased ammonia and urea

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5
Q

lipid metabolism

A

increased triglycerides and cholesterol

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6
Q

drug metabolism

A

increased drug half life

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7
Q

bile acid metabolism

A

increased bile acids

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8
Q

liver maintains circulating concentration of glucose, which depends on ability to store a supply of ___ in a polymerized form as ____; and the ability to synthesize glucose during _____

A

glucose; glycogen; gluconeogenesis

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9
Q

____ stores more glycogen than liver, but has go glucose-6-phosphatase so cannot directly put glucose in blood

A

muscle

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10
Q

____ has gluconeogenetic enzymes and glucose-6-phosphatase but cannot store glycogen

A

kidney

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11
Q

plasma proteins synthesized in the liver

A
  • albumin
  • coagulation factors
  • plasma alpha and beta globulins
  • acute phase proteins
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12
Q

production of acute phase proteins is stimulated by ____ released by ____

A

proinflammatory cytokines; macrophages (IL-1, TNF-a, and IL-6)

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13
Q

binding proteins, opsonins, such as ____ bind to macromolecules released by damaged tissue or infective agents and promote their phagocytosis

A

C-reactive protein (CRP)

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14
Q

genetic deficiency of ____ presents in infancy as liver disease or in adulthood as lung disease (protease inhibitor)

A

alpha1-antitrypsin

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15
Q

genetic deficiency of ____ leads to wilson’s disease, condition assoc with liver and CNS damage

A

ceruloplasmin (copper-carrying protein)

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16
Q

liver cancer assoc with high plasma concentrations of ____

A

alpha-fetoprotein

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17
Q

plasma proteins and membrane receptors are endocytosed and then hydrolyzed by ____ in intracellular organelles known as ____

A

acid proteases; lysosomes

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18
Q

intracellular proteins are degraded within structures known as ____by the _____

A

proteasomes; ubiquitin-proteasome system

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19
Q

____ marks intracellular proteins for proteasomal degradation

A

ubiquitin

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20
Q

____ is essential for the removal of nitrogen generated by amino acid metabolism

A

urea cycle

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21
Q

catabolism of amino acids generates ____ and ____

A

ammonia (NH3); ammonium ions (NH4+)

22
Q

most ammonia is detoxified at the site of its formation by amidation of ____ to ____, which is mainly derived from muscle and used as an energy source by enterocytes

A

glutamate; glutamine

23
Q

remaining N enters portal vein either as ____ or ____, both of which are used by the liver for the synthesis of urea

A

ammonia; alanine

24
Q

Heme, a constituent of ____, ____, and ____, is synthesized in most cells of the body

A

Hb, Mb, and cytochromes

25
Q

heme is the ____ common to Hb and Mb

A

O2 binding moeity

26
Q

the ___ is the main nonerythrocyte source of heme synthesis

A

liver

27
Q

____ and ____ condense to form 5-aminolevulinate (5-ALA); this rxn is catalyzed by ____, located in mitochondria, and is rate-limiting in heme synthesis

A

glycine; succinyl-coenzyme A; 5-ALA synthase

28
Q

in the cytosol, two molecules of 5-ALA condense to form a molecule containing a pyrrole ring, ______

A

porphobilinogen (PBG)

29
Q

4 PBG molecules combine to form a linear tetrapyrrole compound, which cyclizes to yield _____ and ____

A

uroporphyrinogen III ; coporphyrinogen III

30
Q

final stages of pathway occur in mitochondria where a series of decarboxylation and oxidation of side chains in _____ yield _____

A

uroporphyrinogen III; protoporphyrin IX

31
Q

at final stage, ____ is added by ____ to protoporphyrin IX to form heme

A

Fe2+ ; ferrochelatase

32
Q

heme controls the rate of its synthesis by inhibiting _____

A

5-ALA synthase

33
Q

____ is the catabolic product of heme

A

bilirubin

34
Q

75% of all bilirubin is derived from ____ of senescent _____

A

hemoglobin; red blood cells

35
Q

____ is soluble, but ____ is not, so it must be transported by carrier proteins

A

biliverdin; bilirubin

36
Q

conjugated bilirubin in the gut is catabolized by ____

A

bacteria

37
Q

____ is responsible for color of feces

A

stercobilinogen (fecal urobilin)

38
Q

____ is result of imbalance betw bilirubin production/excretion

A

hyperbilirubinemia

39
Q

3 main causes of jaundice

A
  1. prehepatic- increased production of bilirubin
  2. intrahepatic- impaired hepatic uptake, conjugation, or secretion of bilirubin
  3. posthepatic- obstruction to biliary drainage
40
Q

phase I and II of drug metabolism by the liver

A

I- addition of polar group, mediated by cytochrome P-450 (CYP)
II- conjugation, mediated by cytoplasmic enzymes (sulfation, acetylation, methylation)

41
Q

active site of CYP contains a ___ iron center, important for the oxidation of organic substances

A

heme

42
Q

CYP enzymes are ____ proteins that colocalize with ____; ____ is required for electron transfer

A

heme-containing; NADPH; cytochrome P-450 reductase

43
Q

CYPs are present in ____; most metabolism assoc with them takes place in ___ but they are also present in epithelium of ____

A

endoplasmic reticulum; liver; small intestine

44
Q

3 of 12 cytochrome P450 gene families that do most of phase I drug metabolism

A

CYP1, CYP2, and CYP3

45
Q

taken in normal doses, acetaminophen is conjugated with ____ or ____, which is then excreted by the kidneys

A

glucuronic acid; sulfate

46
Q

overdose of acetaminophen can cause ____ of membrane lipids and consequently hepatocellular damage

A

free-radical mediated peroxidation

47
Q

ethanol oxidized in the liver, mainly by ____ to form ____, which is in turn oxidized by aldehyde dehydrogenase (ALDH) to acetate

A

alcohol dehydrogenase; acetaldehyde

48
Q

liver damage in patients who abuse alcohol may arise form the toxicity of ____, which forms ____ with other macromolecules

A

acetaldehyde; schiff base adducts

49
Q

____ and ____ are involved in the interconversion of amino and ketoacids, and are required for metabolism of nitrogen and carbohydrates

A

aspartate aminotransferase (AST); alanine aminotransaminase (ALT)

50
Q

AST and ALT are both found in the ____; ___ is also found in cytoplasm

A

mitochondria; ALT

51
Q

pt with liver disease would be expected to have prolonged ____ and low ____

A

prothrombin time; serum albumin concentration

52
Q

____ is synthesized by both the biliary tract and by bone, but these two tissues contain different ____ isoenzymes

A

alkaline phosphatase (ALP); ALP

Biochem (14 decks)

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