liver metabolism

Question 1

heme catabolism

Answer 1

increased bilirubin

Question 2

carbohydrate metabolism

Answer 2

increased glucose

Question 3

protein synthesis

Answer 3

increased albumin

increased prothrombin time

Question 4

protein catabolism

Answer 4

increased ammonia and urea

Question 5

lipid metabolism

Answer 5

increased triglycerides and cholesterol

Question 6

drug metabolism

Answer 6

increased drug half life

Question 7

bile acid metabolism

Answer 7

increased bile acids

Question 8

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 _____

Answer 8

glucose; glycogen; gluconeogenesis

Question 9

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

Answer 9

muscle

Question 10

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

Answer 10

kidney

Question 11

plasma proteins synthesized in the liver

Answer 11

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

Question 12

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

Answer 12

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

Question 13

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

Answer 13

C-reactive protein (CRP)

Question 14

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

Answer 14

alpha1-antitrypsin

Question 15

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

Answer 15

ceruloplasmin (copper-carrying protein)

Question 16

liver cancer assoc with high plasma concentrations of ____

Answer 16

alpha-fetoprotein

Question 17

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

Answer 17

acid proteases; lysosomes

Question 18

intracellular proteins are degraded within structures known as ____by the _____

Answer 18

proteasomes; ubiquitin-proteasome system

Question 19

____ marks intracellular proteins for proteasomal degradation

Answer 19

ubiquitin

Question 20

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

Answer 20

urea cycle

Question 21

catabolism of amino acids generates ____ and ____

Answer 21

ammonia (NH3); ammonium ions (NH4+)

Question 22

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

Answer 22

glutamate; glutamine

Question 23

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

Answer 23

ammonia; alanine

Question 24

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

Answer 24

Hb, Mb, and cytochromes

Question 25

heme is the ____ common to Hb and Mb

Answer 25

O2 binding moeity

Question 26

the ___ is the main nonerythrocyte source of heme synthesis

Answer 26

liver

Question 27

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

Answer 27

glycine; succinyl-coenzyme A; 5-ALA synthase

Question 28

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

Answer 28

porphobilinogen (PBG)

Question 29

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

Answer 29

uroporphyrinogen III ; coporphyrinogen III

Question 30

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

Answer 30

uroporphyrinogen III; protoporphyrin IX

Question 31

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

Answer 31

Fe2+ ; ferrochelatase

Question 32

heme controls the rate of its synthesis by inhibiting _____

Answer 32

5-ALA synthase

Question 33

____ is the catabolic product of heme

Answer 33

bilirubin

Question 34

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

Answer 34

hemoglobin; red blood cells

Question 35

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

Answer 35

biliverdin; bilirubin

Question 36

conjugated bilirubin in the gut is catabolized by ____

Answer 36

bacteria

Question 37

____ is responsible for color of feces

Answer 37

stercobilinogen (fecal urobilin)

Question 38

____ is result of imbalance betw bilirubin production/excretion

Answer 38

hyperbilirubinemia

Question 39

3 main causes of jaundice

Answer 39

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

Question 40

phase I and II of drug metabolism by the liver

Answer 40

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

Question 41

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

Answer 41

heme

Question 42

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

Answer 42

heme-containing; NADPH; cytochrome P-450 reductase

Question 43

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

Answer 43

endoplasmic reticulum; liver; small intestine

Question 44

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

Answer 44

CYP1, CYP2, and CYP3

Question 45

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

Answer 45

glucuronic acid; sulfate

Question 46

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

Answer 46

free-radical mediated peroxidation

Question 47

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

Answer 47

alcohol dehydrogenase; acetaldehyde

Question 48

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

Answer 48

acetaldehyde; schiff base adducts

Question 49

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

Answer 49

aspartate aminotransferase (AST); alanine aminotransaminase (ALT)

Question 50

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

Answer 50

mitochondria; ALT

Question 51

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

Answer 51

prothrombin time; serum albumin concentration

Question 52

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

Answer 52

alkaline phosphatase (ALP); ALP