Biochem 44 Flashcards

Loss of which liver-resident immune cell most directly explains impaired early antitumor defense?
A. Kupffer macrophages
B. Pit NK cells
C. Ito stellate cells
D. Cholangiocytes

A new anticonvulsant is primarily metabolized by cytochrome P450. Where are these enzymes classically located?
A. Smooth ER
B. Rough ER
C. Cytosol
D. Mitochondrial matrix

After taking a lipophilic drug, the first metabolic step exposes a hydroxyl group to enable later conjugation. Which detoxification phase is this?
A. Phase II
B. Biliary secretion
C. Renal filtration
D. Phase I

A xenobiotic is made more water-soluble by addition of glycine, sulfate, or glucuronic acid. Which detoxification phase best fits?
A. Phase I
B. Beta oxidation
C. Phase II
D. Urea synthesis

A patient on a statin drinks grapefruit juice daily and develops myalgias with elevated CK and transaminases. What mechanism best explains toxicity?
A. CYP2E1 inhibition
B. Decreased gut absorption
C. Increased renal clearance
D. CYP3A4 inhibition

During cytochrome P450 detoxification, which reactive intermediate classically forms and can contribute to tissue injury?
A. Carbocation
B. Free radical
C. Nitrate
D. Disaccharide

A plastics factory worker exposed to vinyl chloride forms chloroethylene oxide via a Phase I reaction. Which enzyme most directly catalyzes this activation?
A. CYP2E1
B. CYP3A4
C. CYP1A2
D. CYP2C9

Vinyl chloride can be converted to chloroacetaldehyde, then safely eliminated after conjugation with which molecule?
A. Sulfate
B. Glycine
C. Reduced glutathione
D. Glucuronic acid

Chloroethylene oxide contributes to carcinogenesis by forming adducts with which DNA base?
A. Cytosine
B. Guanine
C. Adenine
D. Thymine

Long-term vinyl chloride exposure is most classically associated with which hepatic malignancy?
A. Hepatoblastoma
B. Cholangiocarcinoma
C. Hepatocellular carcinoma
D. Hepatic angiosarcoma

A patient eats mold-contaminated stored peanuts and later develops hepatocellular carcinoma risk from aflatoxin exposure. Which organism produced the toxin?
A. Aspergillus flavus
B. Candida albicans
C. Histoplasma capsulatum
D. Penicillium chrysogenum

Aflatoxin B1 promotes hepatocarcinogenesis most directly through a G→T mutation in which gene?
A. RB1
B. APC
C. p53
D. BRCA1

Bioactivation of aflatoxin B1 to its 8,9-epoxide form is most directly mediated by which enzyme?
A. CYP2E1
B. CYP3A4
C. CYP2A1
D. CYP1A2

The 8,9-epoxide of aflatoxin B1 forms covalent DNA adducts predominantly with which base?
A. Thymine
B. Guanine
C. Cytosine
D. Adenine

In addition to DNA damage, aflatoxin B1 epoxide can bind proteins by reacting with which amino acid residue?
A. Serine
B. Histidine
C. Cysteine
D. Lysine

A patient takes therapeutic-dose acetaminophen. Its reactive metabolite is rendered safe for urinary excretion primarily by conjugation with:
A. Glutathione
B. Sulfate
C. Glycine
D. Glucuronic acid

After a massive acetaminophen ingestion, which pathways are overwhelmed, increasing formation of the toxic metabolite?
A. Ketogenesis and lipolysis
B. Urea cycle enzymes
C. Bile salt transport
D. Sulfation and glucuronidation

A patient with acetaminophen overdose develops hepatocyte necrosis due to an unstable metabolite. Which metabolite is responsible?
A. Acetyl-CoA
B. Acetylaldehyde
C. NAPQI
D. Urobilinogen

The enzyme that produces NAPQI and is inducible by alcohol is:
A. CYP2E1
B. CYP2A1
C. CYP3A4
D. UGT1A1

A chronic alcohol user develops severe acetaminophen toxicity after a dose that was previously tolerated. The best explanation is:
A. Lower portal blood flow
B. More CYP2E1 activity
C. Less NAPQI formation
D. Faster renal clearance

A patient has high dietary cholesterol intake with efficient intestinal absorption. What hepatic compensation is most expected?
A. Increases cholesterol synthesis
B. Decreases cholesterol export
C. Decreases cholesterol synthesis
D. Increases ketone production

A patient with liver failure develops hyperammonemia. Which organ is primarily responsible for synthesizing urea under normal conditions?
A. Kidney cortex
B. Skeletal muscle
C. Small intestine
D. Liver

Most nitrogen destined for hepatic urea synthesis arrives primarily carried on which molecules?
A. Lactate and pyruvate
B. Glutamine and alanine
C. Leucine and lysine
D. Serine and proline

Most protein entering the GI tract is metabolized by bacteria, releasing which species that enters the portal vein?
A. Ammonium ion
B. Urea
C. Nitrate
D. CO2

What mechanism most directly explains hepatic encephalopathy here?
A. Bilirubin blocks synapses
B. Hypoglycemia causes seizures
C. Systemic ammonium reaches brain
D. Lactate causes brain acidosis

In hepatic ethanol metabolism, the principal cytochrome P450 enzyme oxidizing ethanol to acetylaldehyde is:
A. CYP1A2
B. CYP2C9
C. CYP3A4
D. CYP2E1

The term “microsomal enzymes” most directly refers to:
A. Smooth ER P450s
B. Mitochondrial oxidases
C. Lysosomal hydrolases
D. Cytosolic kinases

Sialic acid found on serum proteins is also known as:
A. N-acetylmuramic acid
B. N-acetylneuraminic acid
C. N-acetylglucosamine
D. N-acetylgalactosamine

Sialic acid (NANA) made by the liver is best characterized as which surface feature of serum proteins?
A. N-linked oligosaccharide
B. Lipid anchor
C. Phosphorylated tag
D. O-linked sugar

If statins are taken regularly with grapefruit juice, statin levels may rise approximately:
A. 2-fold
B. 5-fold
C. 15-fold
D. 50-fold

The key functional outcome of Phase II reactions is best summarized as:
A. Adds negative charged group
B. Removes reactive oxygen species
C. Cleaves peptide bonds
D. Generates acetyl-CoA

A patient with impaired liver innate immunity is unusually susceptible to hepatic viral invasion. Which cell type normally provides liver-specific NK defense?
A. Kupffer macrophages
B. Pit NK cells
C. Ito stellate cells
D. Endothelial cells

A patient with reduced hepatic clearance has prolonged half-life of an “aged” serum glycoprotein. Which change normally flags serum proteins for removal and degradation?
A. Added fucose residues
B. Loss of NANA residues
C. Added phosphate residues
D. Increased disulfide bonding

A transfusion service develops a test for oxidative stress tolerance in RBCs. Which pathway’s major function best supports this defense by generating NADPH and 5-carbon sugars?
A. Glycolysis
B. TCA cycle
C. Beta oxidation
D. Pentose phosphate pathway

NADPH is most critical for maintaining activity of which enzyme?
A. Glutathione reductase
B. Glutathione peroxidase
C. Superoxide dismutase
D. Catalase

In severe oxidative stress, oxidized glutathione accumulates. Which reaction is directly catalyzed by glutathione reductase?
A. GSH → GSSG
B. NADP+ → NADPH
C. GSSG → GSH
D. H2O2 → H2O

A patient has markedly decreased glutathione reductase activity. Loss of which protection is most direct?
A. Ketone body utilization
B. Free radical injury defense
C. Bile acid conjugation
D. Urea cycle function

Which pathway is required in all cells for ribose generation, especially rapidly dividing cells?
A. Pentose phosphate pathway
B. Cori cycle
C. Malate-aspartate shuttle
D. Carnitine shuttle

After a high-carbohydrate meal, hepatic glucose uptake increases sharply. This dependence on high portal glucose is best explained by which shared property?
A. Low Km for both proteins
B. Insulin-independent nuclear transport
C. Constitutive mitochondrial localization
D. High Km for both proteins

A fasting hepatocyte shows reduced cytosolic glucokinase activity. In the absence of glucose, glucokinase is partially sequestered where and bound to what?
A. Cytosol; insulin receptor
B. Smooth ER; PPARα
C. Nucleus; GK regulatory protein
D. Mitochondria; CPT1

A patient receives a drug that increases hepatic fructose-2,6-bisphosphate. What is the net effect on glycolysis rate?
A. Decreases markedly
B. Increases
C. No change
D. Cycles with feeding

A 48-hour fast shifts the liver’s primary fuel source. Which substrate is the major fuel for the liver during fasting?
A. Long-chain fatty acids
B. Short-chain fatty acids
C. Glucose from portal vein
D. Branched-chain amino acids

A newborn has accumulation of very-long-chain fatty acids (C20–C26). These fatty acids are first activated to CoA derivatives by an enzyme located in the:
A. Mitochondrial matrix
B. Cytosolic ribosomes
C. Rough ER lumen
D. Peroxisomal membrane

During fasting, hepatic gene transcription increases for fatty acid uptake and oxidation proteins. Which receptor directly regulates these genes?
A. SREBP-1c
B. LXR
C. PPAR
D. FXR

A patient with high circulating free fatty acids shows increased transcription of fatty-acid metabolism proteins. Fatty acids act as endogenous ligands for which liver-dominant isoform?
A. PPARα
B. PPARγ
C. PPARδ
D. PPARβ

A patient ingests benzoate-containing food preservatives. Benzoate (and salicylic acid) resemble medium-chain fatty acids and are activated to acyl-CoA derivatives by which enzyme?
A. Very-long-chain acyl-CoA synthetase
B. Medium-chain fatty acyl-CoA enzyme
C. LCAT
D. Glucokinase

After activation, benzoate and salicylic acid are targeted for urinary excretion by conjugation with:
A. Glucuronic acid
B. Sulfate
C. Glutathione
D. Glycine

A cirrhotic patient has elevated plasma triglycerides without major dietary change. The most direct mechanism is decreased activity of:
A. LCAT and ACAT
B. ApoA-I and CETP
C. LPL and hepatic TG lipase
D. LDL receptor and PCSK9

A patient with hepatocellular disease has reduced cholesterol ester formation. Decreased activity of which enzyme best explains this?
A. lecithin-cholesterol acyltransferase
B. LDL receptor and PCSK9
C. Very-long-chain acyl-CoA synthetase
D. CETP

A toxicologist notes that multiple organs serve excretory roles with broad detoxifying mechanisms. Besides liver, which organs fit this description?
A. Lung and spleen
B. Kidney and gut
C. Brain and skin
D. Bone marrow and thymus

Approximately 75% of the liver’s blood supply normally arrives via the:
A. Hepatic artery
B. Splenic artery
C. Celiac trunk
D. Portal vein

Which organ’s venous blood is not a typical contributor to portal venous inflow?
A. Stomach
B. Pancreas
C. Kidney
D. Spleen

A pathologist describes “expandable vascular channels” running through hepatic lobules. Which structure is being described?
A. Sinusoids
B. Central veins
C. Bile canaliculi
D. Portal triads

Drug molecules in plasma rapidly access hepatocytes across a “leaky” barrier in hepatic lobules. Which cells line this leaky channel?
A. Hepatocytes
B. Endothelial cells
C. Stellate cells
D. Cholangiocytes

A patient with obstructive cholestasis has impaired exocrine output from the liver. What is the primary exocrine secretion?
A. Albumin
B. Urea
C. Complement proteins
D. Bile

During biliary drainage, lumina of bile ducts fuse and ultimately form the:
A. Cystic duct
B. Hepatic duct
C. Common bile duct
D. Pancreatic duct

A surgeon notes a fibrous covering enveloping the entire liver surface and sending septa inward (Glisson's capsule). This covering is primarily:
A. Connective tissue capsule
B. Simple squamous epithelium
C. Smooth muscle sheath
D. Elastic cartilage plate

A histology slide shows the dominant cell type by volume within liver parenchyma. Which cell type composes most liver volume?
A. Kupffer cells
B. Hepatocytes
C. Cholangiocytes
D. Endothelial cells

Despite normally low turnover, which feature best explains why hepatocytes can restore liver mass?
A. Constitutive mitosis at baseline
B. Stem-cell-only regeneration
C. Stimulated growth after damage
D. Permanent post-mitotic state

A patient with bacteremia has rapid clearance of microbes from portal blood. Which liver-resident cell type provides endocytotic and phagocytic capacity?
A. Stellate cells
B. Pit cells
C. Cholangiocytes
D. Kupffer cells

A lab intentionally removes terminal residues from serum glycoproteins and observes accelerated clearance from blood. Which residue’s loss triggers this clearance signal?
A. Mannose
B. Sialic acid
C. Glucose
D. Ribose

A patient with low NADPH cannot maintain reduced glutathione stores. Which enzyme activity is most directly compromised by NADPH deficiency?
A. LCAT
B. MMFAE
C. Glucokinase
D. Glutathione reductase

A lipid profile suggests selective impairment in handling very-long-chain fatty acids. Which chain length most specifically matches the peroxisome-activated group?
A. C20–C26
B. C6–C10
C. C12–C18
D. C2–C4

A patient takes aspirin chronically; hepatic handling of salicylic acid involves glycine conjugation. Which glycine conjugate corresponds to benzoate specifically?
A. Salicylurate
B. Glucuronate
C. Hippurate
D. Sulfate ester

A patient with hepatocellular disease has a lipid abnormality most directly predicted by reduced LPL and hepatic TG lipase. Which abnormality is expected?
A. Low triglycerides
B. Elevated triglycerides
C. Low LDL particles
D. Elevated cholesterol esters

A fed-state signal increases hepatic fructose-2,6-bisphosphate. Which pathway’s rate rises as a direct consequence?
A. Glycolysis
B. Glycogenolysis
C. Gluconeogenesis
D. Ketogenesis

After a high-carb meal, glucose enters hepatocytes efficiently because hepatic uptake is tuned for high portal glucose. Which transporter best fits this “high Km” role?
A. GLUT1
B. GLUT4
C. GLUT2
D. SGLT1

The remaining ~25% of the liver’s blood supply is delivered by the:
A. Inferior vena cava
B. Splenic vein
C. Hepatic artery
D. Portal vein

A patient with hereditary spherocytosis has increased RBC turnover. Which liver cell type directly removes damaged erythrocytes from circulation?
A. Kupffer cells
B. Stellate cells
C. Pit cells
D. Cholangiocytes

A biopsy shows lipid-filled perisinusoidal cells with vitamin A droplets. What is the alternate name for these cells?
A. Kupffer cells
B. Ito cells
C. Pit cells
D. Endothelial cells

The primary hepatic storage site for vitamin A is:
A. Hepatocytes
B. Kupffer cells
C. Stellate cells
D. Bile duct cells

A cirrhotic patient has progressive portal hypertension and fibrosis. Which cell type is most responsible for increased extracellular matrix synthesis in cirrhosis?
A. Hepatocytes
B. Kupffer cells
C. Pit cells
D. Stellate cells

In cirrhosis, stellate cell activation most directly increases synthesis of:
A. Urea cycle enzymes
B. Extracellular matrix material
C. Bile salts
D. Albumin

Which cell type normally regulates sinusoidal contractility and connective tissue turnover?
A. Stellate cells
B. Kupffer cells
C. Pit cells
D. Cholangiocytes

A patient with metastatic cancer shows early hepatic tumor surveillance failure. “Liver-associated lymphocytes” that mediate this defense are:
A. CD4 T cells
B. Natural killer cells
C. Plasma cells
D. Neutrophils

Hepatic “pit cells” are best classified as which immune effector type?
A. Natural killer cells
B. Dendritic cells
C. Macrophages
D. Eosinophils

A toxic compound absorbed from the gut is cleared by the liver and targeted for excretion primarily into:
A. Sweat or saliva
B. Urine or bile
C. CSF or tears
D. Lymph or sputum

A clinician explains why the liver sees gut-derived toxins early after ingestion. Which concept best captures this “first access” physiology?
A. Lymphatic drainage
B. Enterohepatic circulation
C. Renal portal system
D. Coronary circulation

The liver’s first access to portal blood most directly supports synthesis of which protein class?
A. Keratins
B. Myosins
C. Coagulation proteins
D. Collagens

After a meal, the liver rapidly processes incoming substrates for nucleotide synthesis. Which products are specifically listed functions supported by first access?
A. Heme, purines, pyrimidines
B. Glycogen, lactate, ketones
C. Cholesterol, bile acids, urea
D. Creatine, carnitine, heme

Gut bacteria generate NH4+ that can reach the liver via portal blood. This is best categorized as a:
A. Vitamin cofactor
B. Metabolic product
C. Essential nutrient
D. Structural lipid

Hepatic sinusoids allow efficient exchange with hepatocytes. Which structural feature is notably absent between endothelium and hepatocytes?
A. Tight junctions
B. Basement membrane
C. Glycocalyx
D. Fenestrations

Slow portal blood flow and “leaky” endothelium most directly enhance:
A. Exchange between blood and hepatocytes
B. Myelin formation
C. Lymphocyte thymic selection
D. Bone marrow release

A patient is fasting and uses amino acids for energy. Which statement best reflects hepatic metabolic flexibility?
A. Converts all amino acids to ketones
B. Converts amino acids to multiple fuels
C. Converts amino acids only to glucose
D. Cannot use aromatic amino acids

The liver can convert amino acids found in proteins into:
A. Glucose, fatty acids, ketones
B. Lactate, urea, bilirubin
C. Cholesterol, bile salts, glycogen
D. Creatine, carnitine, citrate

______ is created when VLDL loses triglycerides through the action of lipoprotein lipase.

A patient with hypertriglyceridemia has increased hepatic export of TAG. Which lipoprotein secretion delivers excess calories to adipose for TAG storage?
A. Chylomicrons
B. LDL
C. HDL
D. VLDL

Hepatic VLDL also provides which lipid components to peripheral tissues for membrane needs?
A. Ceramides and bile acids
B. Phospholipids and cholesterol
C. Steroids and ketones
D. Glycogen and glucose

A nuclear medicine study uses a ligand to assess receptor-mediated uptake by hepatocytes. Which receptor is used diagnostically for this purpose?
A. LDL receptor
B. Asialoglycoprotein receptor
C. Insulin receptor
D. Transferrin receptor

The asialoglycoprotein receptor is also known as the:
A. Hepatic binding protein
B. Kupffer receptor
C. Canalicular pump
D. Sinusoid ligand trap

A toxicology question defines xenobiotics. Which property best matches xenobiotics?
A. Provide caloric nutrient value
B. Stored as hepatic glycogen
C. No nutrient value
D. Required vitamin precursors

The principal site for xenobiotic degradation in the body is the:
A. Kidney cortex
B. Liver
C. Skeletal muscle
D. Brain

Many xenobiotics require Phase I processing because they are:
A. Hydrophilic
B. Lipophilic
C. Polyionic
D. Protein-bound only

Phase I reactions most characteristically:
A. Add negatively charged groups
B. Introduce hydroxyl reactive sites
C. Form disulfide bonds
D. Remove oxygen atoms

Conjugation reactions most characteristically add a:
A. Positively charged group
B. Negatively charged group
C. Hydrophobic ring
D. Phosphate-free radical

Which pairing best matches a Phase II conjugation group listed?
A. Glycine, sulfate, glucuronic acid
B. ATP, NADH, FADH2
C. Palmitate, stearate, oleate
D. Glucose, fructose, ribose

A patient has elevated steroid hormone levels due to impaired hepatic clearance. Which Phase II process is specifically used to clear steroid hormones?
A. Sulfation
B. Ureagenesis
C. Deamination
D. Ketogenesis

A smoker’s carcinogen contains a stable aromatic ring that humans cannot readily recycle into useful components. Which compound fits this example?
A. Benzopyrene
B. Lactate
C. Glycine
D. Citrate

Nicotine contains ring structures that are difficult to degrade. These are best described as:
A. Heterocyclic rings
B. Linear ketones
C. Saturated fatty acids
D. Simple aldehydes

Cytochrome P450–dependent monooxygenases are determinants in degradation of both exogenous and endogenous substances. Which is listed as an endogenous substrate class?
A. Steroids
B. Cellulose
C. Hemoglobin
D. Glycogen

The major role of cytochrome P450 enzymes is to:
A. Reduce substrates, remove oxygen
B. Oxidize substrates, add oxygen
C. Polymerize sugars, store glycogen
D. Conjugate glycine, excrete urine

A pharmacologist notes an isoform comprising ~30–40% of hepatic CYP450 and ~70% of gut-wall enterocyte CYP enzymes. Which isoform is this?
A. CYP2E1
B. CYP1A2
C. CYP3A4
D. CYP2A1

A patient taking simvastatin begins a new diet including grapefruit juice daily. Which statement best explains the interaction?
A. Grapefruit induces CYP3A4
B. Grapefruit inhibits CYP3A4
C. Grapefruit inhibits CYP2E1
D. Grapefruit blocks LDL receptors

Statin degradation most directly depends on which enzyme isoform?
A. CYP2C9
B. CYP3A4
C. CYP2D6
D. CYP1A2

A patient has reduced drug metabolism specifically in gut-wall enterocytes. Which hepatic/gut CYP isoform dominates enterocytes?
A. CYP3A4
B. CYP2E1
C. CYP2A1
D. CYP2C19

A patient has impaired microsomal oxidation capacity because the flavin reductase subunit can’t donate electrons. Which cofactor is required?
A. NADPH
B. NADH
C. ATP
D. FADH2

A 52-year-old man begins a highly lipophilic medication that accumulates within hepatocyte membranes. Shortly after, his physician notes altered metabolism of several drugs processed by hepatic monooxygenases. Which structural feature of these enzymes best explains their susceptibility to modulation by membrane-partitioning drugs?

A. Integral membrane localization within smooth ER lipid bilayer
B. Free cytosolic diffusion with soluble catalytic domains
C. Nuclear chromatin binding regulating gene transcription
D. Secretion into plasma for systemic xenobiotic metabolism

A chronic medication accelerates its own metabolism over time. Which shared CYP feature best explains this?
A. Inducible by own substrate
B. Always constitutively expressed
C. Irreversibly inhibited by substrate
D. Active only during fasting

During CYP-dependent oxidation, transient reactive intermediates increase cellular injury risk. What intermediate is classically generated?
A. Disaccharide intermediate
B. Acyl-CoA intermediate
C. Nucleotide intermediate
D. Free radical intermediate

A factory worker is exposed to vinyl chloride daily. The compound is used primarily to make:
A. Steroid hormones
B. Plastics
C. Bile acids
D. Heme intermediates

Years later, that worker develops a rare hepatic malignancy classically linked to vinyl chloride exposure. Which tumor fits best?
A. Hepatoblastoma
B. Cholangiocarcinoma
C. Hepatic angiosarcoma
D. Hepatocellular carcinoma

Which statement best fits?
A. CYP can bioactivate toxins
B. CYP always detoxifies toxins
C. CYP only acts in kidney
D. CYP only conjugates xenobiotics

The CYP isoform listed as making aflatoxin B1 more toxic is:
A. CYP2E1
B. CYP1A2
C. CYP3A4
D. CYP2A1

A patient taking therapeutic acetaminophen clears most of it safely via renal excretion after Phase II processing. Which pathways are listed?
A. Oxidation and reduction
B. Hydrolysis and methylation
C. Glucuronidation or sulfation
D. Deamination and transamination

Why can acetaminophen become toxic at high doses?
A. Bile secretion stops
B. Conjugation pathways become saturated
C. Gut absorption increases
D. Renal filtration ceases

After overdose, a CYP enzyme generates the key toxic intermediate responsible for hepatocyte injury. Which metabolite is it?
A. Biliverdin
B. Acetyl-CoA
C. Urobilinogen
D. N-acetyl-p-benzoquinoneimine

NAPQI causes hepatotoxicity most directly by damaging:
A. Cellular proteins
B. Ribosomal RNA
C. Membrane cholesterol
D. DNA thymine bases

In therapeutic dosing, NAPQI is rendered safe primarily by conjugation with:
A. Sulfate
B. Glutathione
C. Glycine
D. Glucuronic acid

A chronic alcohol user develops severe acetaminophen toxicity at a lower dose. Best explanation?
A. Faster glucuronidation
B. Less CYP activity
C. More NAPQI shunting
D. More renal clearance

Chronic alcohol use increases acetaminophen toxicity risk by increasing levels of:
A. CYP2E1
B. CYP2A1
C. CYP3A4
D. UGT1A1

A patient with acetaminophen poisoning receives an antidote that restores glutathione availability. Which treatment is listed?
A. Fomepizole
B. N-acetylcysteine
C. Deferoxamine
D. Atropine

N-acetylcysteine helps most directly by:
A. Inhibiting CYP active sites
B. Neutralizing NAPQI directly
C. Increasing glutathione stores
D. Increasing renal excretion

During an overnight fast, blood glucose is maintained primarily by:
A. Gluconeogenesis
B. Glycolysis
C. Lipogenesis
D. Glycogenolysis

If gluconeogenesis is required, how much ATP is needed to make one glucose from two pyruvate?
A. 6 ATP
B. 2 ATP
C. 4 ATP
D. 8 ATP

During fasting gluconeogenesis, the energy to meet this ATP requirement is obtained mainly from:
A. Pentose phosphate pathway
B. Glycolysis
C. Fatty acid oxidation
D. Protein synthesis

Compared with most organs, the liver has a much greater demand for:
A. NADH
B. FADH2
C. ATP
D. NADPH

The only organ that can produce ketone bodies is the:
A. Liver
B. Brain
C. Heart
D. Kidney

Despite producing ketone bodies, the liver is listed as being unable to:
A. Export ketones
B. Synthesize ketones
C. Sense circulating ketones
D. Use ketones for energy

Hypoproteinemia causes edema primarily because of:
A. Increased plasma oncotic pressure
B. Decreased lymph formation
C. Low plasma oncotic pressure
D. Reduced capillary permeability

Hepatic NADPH is used for biosynthesis of:
A. Urea and creatinine
B. Heme and globin
C. DNA and RNA
D. Fatty acids, cholesterol, bile salts

Cirrhosis causes portal hypertension that increases back pressure into esophageal veins, promoting:
A. Splenic infarction
B. Esophageal varices
C. Renal vein thrombosis
D. Pulmonary edema

In cirrhosis, reduced coagulation protein synthesis and impaired vitamin K–dependent reactions most directly produce:
A. Prolonged prothrombin time
B. Shortened prothrombin time
C. Prolonged bleeding time
D. Shortened aPTT

When hepatocellular function is compromised, urea-cycle capacity is inadequate and peripheral ammonium contributes to:
A. Wernicke encephalopathy
B. Parkinson disease
C. Hepatic encephalopathy
D. Guillain-Barré syndrome

The most abundant plasma protein produced by the liver is:
A. Fibrinogen
B. Albumin
C. Transferrin
D. Ceruloplasmin

Most sugars secreted by the liver onto proteins are:
A. O-linked glycans
B. N-linked glycans
C. Lipid anchors
D. Phosphate tags

O-linked carbohydrate attachment occurs via the –OH of:
A. Lysine or arginine
B. Aspartate or glutamate
C. Glycine or proline
D. Serine or threonine

A particularly important O-linked sugar made by the liver is:
A. Ribose
B. Mannose
C. N-acetylneuraminic acid
D. Galactose

NANA is synthesized from:
A. Fructose-6-P + PEP
B. Glucose-6-P + citrate
C. Pyruvate + ribose-5-P
D. Acetyl-CoA + OAA

As serum proteins age, loss of NANA residues signals:
A. Increased half-life
B. Nuclear sequestration
C. Bile conjugation
D. Clearance and degradation

Major functions of the pentose phosphate pathway include generation of:
A. NADH and acetyl-CoA
B. NADPH and pentoses
C. ATP and lactate
D. FADH2 and succinate

The liver consumes approximately what fraction of the body’s total oxygen?
A. About 5%
B. About 10%
C. About 20%
D. About 35%

After a binge, which organ is the major site of ethanol oxidation?
A. Kidney
B. Liver
C. Brain
D. Skeletal muscle

Hepatic ethanol oxidation yields principally acetate, then which product?
A. Lactate
B. Pyruvate
C. Acetaldehyde
D. Acetyl-CoA

Hepatic glucose use rate is partly determined by activity of which enzyme?
A. Hexokinase
B. PFK-1
C. Glucokinase
D. Glycogen phosphorylase

The glucokinase regulatory protein is located primarily in the:
A. Nucleus
B. Cytosol
C. Mitochondria
D. Smooth ER

In liver, glucokinase activity is regulated by binding to:
A. Insulin receptor
B. Glucokinase regulatory protein
C. PFK-2
D. GLUT4 transporter

During fasting, the major lipids oxidized as hepatic fuels are:
A. Long-chain fatty acids
B. Ketone bodies
C. Medium-chain fatty acids
D. Short-chain fatty acids

Palmitic, stearic, and oleic acids are major lipids ingested mainly from:
A. Fruits
B. Grains
C. Meat or dairy
D. Leafy vegetables

Fatty acids in infants usually enter via maternal milk as:
A. Free fatty acids
B. Phospholipids
C. Cholesteryl esters
D. Medium-chain triacylglycerols

MCT supplements help malabsorption patients mainly because they provide:
A. Easily absorbed calories
B. Increased bile salt production
C. Increased lymphatic transport
D. Enhanced pancreatic lipase activity

A child with steatorrhea from low pancreatic enzymes needs calories. Best supplement?
A. MCTs
B. Long-chain triglycerides
C. Fish oil capsules
D. Cholesterol esters

A patient with cholestasis and low intraluminal bile salts needs calories. Best fat source?
A. Long-chain triglycerides
B. MCT supplements
C. Plant sterols
D. Omega-3 phospholipids

A stone obstructs the common bile duct causing fat malabsorption. Best calorie fat?
A. MCT supplements
B. Long-chain triglycerides
C. Cholesterol esters
D. Wax esters

Compared with other tissues, peroxisomes are present in greatest numbers in:
A. Liver
B. Heart
C. Brain
D. Skeletal muscle

Oxidation of very-long-chain fatty acids (e.g., C24:0) occurs primarily in:
A. Mitochondria
B. Smooth ER
C. Peroxisomes
D. Cytosol

Peroxisomes detoxify which reactive molecule using catalase?
A. Superoxide
B. Nitric oxide
C. Peroxynitrite
D. Hydrogen peroxide

Cleavage of the cholesterol side chain for bile salt synthesis occurs in:
A. Lysosomes
B. Mitochondria
C. Peroxisomes
D. Golgi apparatus

A step in ether lipid biosynthesis occurs in the:
A. Rough ER
B. Peroxisome
C. Cytosol
D. Nucleus

Several steps of arachidonic acid metabolism occur in:
A. Mitochondria
B. Golgi
C. Peroxisomes
D. Ribosomes

The key peroxisomal enzyme that detoxifies hydrogen peroxide is:
A. Catalase
B. Myeloperoxidase
C. Xanthine oxidase
D. Glutathione reductase

A neonate has a cerebrohepatorenal (Zellgewer) syndrome due to absence of which organelle?
A. Lysosomes
B. Mitochondria
C. Smooth ER
D. Peroxisomes

In Zellweger syndrome, which fatty acids accumulate in brain tissue?
A. C8 to C12
B. C26 to C38
C. C14 to C18
D. C2 to C4

In Zellweger syndrome, there is defective oxidation of very-long-chain fatty acids used for:
A. ATP synthesis
B. Myelin formation
C. Steroid receptors
D. Glycogen storage

PPARs were named because agonists can induce hepatic:
A. Glycogen depletion
B. Ketone breakdown
C. Bile flow
D. Peroxisome proliferation

Which PPAR isoform is the major form in liver?
A. PPAR-α
B. PPAR-γ
C. PPAR-δ/β
D. PPAR-ε

A patient with hypertriglyceridemia starts clofibrate. This drug class binds:
A. LXR
B. FXR
C. SREBP-1c
D. PPARs

Fibrates are typically prescribed for patients with:
A. Low HDL
B. Elevated triglycerides
C. Elevated LDL only
D. Isolated hyperuricemia

Fibrate therapy lowers triglycerides primarily by increasing:
A. Cholesterol esterification
B. ApoB-48 synthesis
C. Triglyceride oxidation
D. De novo lipogenesis

Suppressing apoCIII levels lowers plasma triglycerides by allowing more:
A. IDL endocytosis
B. HDL secretion
C. VLDL assembly
D. Chylomicron formation

The glycine conjugate of salicylate is called:
A. Hippurate
B. Glycocholate
C. Salicylurate
D. Urobilinogen

A child develops vomiting and progressive CNS dysfunction after a viral illness. Diagnosis?
A. Wilson disease
B. Reye syndrome
C. Acute pancreatitis
D. Crigler–Najjar syndrome

Reye syndrome is classically associated with children using which drug during viral illness?
A. Ibuprofen
B. Acetaminophen
C. Aspirin
D. Diphenhydramine

Autopsy in fatal Reye syndrome most characteristically shows:
A. Swollen disrupted mitochondria
B. Portal vein thrombosis
C. Bridging collagen septa
D. Iron-laden hepatocytes

Reye syndrome autopsy also shows fatty vacuolization in:
A. Heart and spleen
B. Brain and pancreas
C. Liver and renal tubules
D. Lung and marrow

A cirrhotic patient has elevated circulating nonesterified fatty acids. Which marker is high?
A. LDL cholesterol
B. ApoA-I
C. LCAT activity
D. NEFA

Hepatocyte injury releases which enzymes, elevating them in plasma?
A. ALP and GGT
B. ALT and AST
C. CK and troponin
D. Amylase and lipase

In liver disease, jaundice most directly reflects impaired:
A. Heme synthesis
B. Bilirubin glucuronidation
C. Bile acid reuptake
D. Albumin degradation

A major change that occurs when fibrosis is initiated is that the normally “sparse” or “leaky” basement membrane between the endothelial cell and the hepatocyte is replaced with a high-density membrane containing
A. Laminin
B. Elastin
C. Keratin
D. Fibrillar collagen

Peroxisome Proliferator-Activated Receptors (PPARs) are a family of nuclear receptor proteins that function as ______ ______ regulating gene expression related to lipid metabolism, glucose homeostasis, and cell differentiation.

PPARα: Highly expressed in the liver, heart, and muscle, it regulates ______ ______ oxidation.