[01.02] Cell Injury & Death (Mechanisms of Cell Injury, Apoptosis, Intracellular Accumulations, Pathologic Calcifications)

Apoptosis

What form of cell death involves caspase activation, DNA fragmentation, and no inflammation?

Necrosis

Which form of cell death is unregulated, often results in inflammation, and is associated with plasma membrane rupture?

Intrinsic pathway

Which apoptotic pathway involves cytochrome c release from mitochondria into the cytoplasm?

Extrinsic pathway

Which apoptotic pathway is initiated by Fas ligand binding to Fas receptor?

BAX and BAK

Which pro-apoptotic proteins increase mitochondrial membrane permeability?

BCL2 and BCL-XL

Which anti-apoptotic proteins prevent cytochrome c leakage from mitochondria?

Caspase-9

Which caspase is activated by the apoptosome in the intrinsic apoptotic pathway?

Caspase-8

Which caspase is activated through the FADD complex in the extrinsic pathway?

Cytochrome c

Which mitochondrial protein initiates apoptosis upon release into the cytoplasm?

Apoptosome

What structure forms when cytochrome c binds APAF-1 and activates caspase-9?

FADD

What protein binds to caspase-8 in the extrinsic pathway of apoptosis?

FLIP

Which viral protein inhibits caspase-8 activation in the extrinsic apoptotic pathway?

Executioner caspases

What class of caspases is responsible for structural and nuclear degradation in apoptosis?

Phosphatidylserine

What molecule flips to the outer membrane to signal phagocytosis of apoptotic cells?

BAD, BIM, BID

Which BH3-only proteins regulate the balance between pro- and anti-apoptotic factors?

p53

Which tumor suppressor protein halts the cell cycle or triggers apoptosis in response to DNA damage?

H&E stain

Which staining technique reveals apoptotic cells as eosinophilic with condensed chromatin?

Necroptosis

Which cell death pathway mimics necrosis but is regulated and caspase-independent?

RIPK1 and RIPK3

Which kinases mediate necroptosis through MLKL phosphorylation?

MLKL

Which protein disrupts the plasma membrane during necroptosis?

Pyroptosis

Which inflammatory cell death involves caspase-1 and IL-1β activation?

Inflammasome

What structure activates caspase-1 in pyroptosis?

Caspases 1, 4, 5

Which caspases mediate pyroptosis and IL-1 production?

Ferroptosis

Which iron-dependent form of cell death results from lipid peroxidation?

Glutathione

Which antioxidant system is overwhelmed in ferroptosis?

Ischemia

Which clinical condition causes the most common form of cell injury?

Hypoxia-inducible factor-1 (HIF-1)

Which transcription factor helps cells survive hypoxic stress?

Reperfusion injury

Which injury worsens after restoring blood flow due to ROS and inflammation?

CCl4

Which chemical causes liver injury via conversion to toxic free radicals?

Cytochrome P450

Which enzyme system in the liver activates many toxic metabolites?

Mitochondria

Which organelle is the major source and target of cellular injury?

ATP depletion

Which consequence of mitochondrial damage leads to pump failure and cell swelling?

Na+/K+ ATPase

Which membrane pump fails during ATP depletion, leading to electrolyte imbalance?

Anaerobic glycolysis

What metabolic pathway compensates during ATP depletion but causes acidosis?

Lactic acid

What compound accumulates during anaerobic metabolism, lowering pH?

Ribosome detachment

What cellular change indicates disrupted protein synthesis during injury?

Lipid peroxidation

Which process damages membranes due to ROS attack on fatty acids?

Hydroxyl radical

Which ROS is considered the most reactive and damaging?

Superoxide dismutase

Which enzyme converts superoxide into hydrogen peroxide?

Catalase

Which enzyme converts hydrogen peroxide into water and oxygen?

Glutathione peroxidase

Which enzyme detoxifies hydrogen peroxide using GSH?

Peroxynitrite

Which reactive nitrogen species forms from nitric oxide and superoxide?

DNA strand breaks

What nuclear damage is commonly caused by ROS?

Calcium

Which ion, when overloaded intracellularly, activates destructive enzymes?

Phospholipases

Which calcium-activated enzymes degrade membrane lipids?

Proteases

Which enzymes degrade cytoskeletal and membrane proteins during calcium overload?

Endonucleases

Which enzymes fragment DNA during calcium-mediated injury?

ATPases

Which enzymes further deplete ATP when calcium levels rise?

Unfolded protein response

Which ER mechanism attempts to restore proper protein folding?

ER stress

What happens when misfolded proteins accumulate and overwhelm the ER?

Alpha-1 antitrypsin deficiency

Which disease involves defective protein folding in hepatocytes?

Amyloid beta

Which peptide aggregates in neurons in Alzheimer’s disease?

Tay-Sachs

Which lysosomal storage disease results from hexosaminidase deficiency?

Familial hypercholesterolemia

Which disease is due to defective LDL receptors?

Prions

Which misfolded infectious proteins cause Creutzfeldt-Jakob disease?

Steatosis

Which term refers to abnormal triglyceride accumulation in the liver?

Foam cells

Which lipid-laden cells form in atherosclerotic plaques?

Xanthomas

What skin lesions are caused by cholesterol accumulation in connective tissue?

Cholesterolosis

Which gallbladder condition shows cholesterol-laden macrophages?

Niemann-Pick disease type C

Which disease results in defective cholesterol trafficking and storage?

Russel bodies

Which eosinophilic inclusions represent accumulated antibodies in plasma cells?

Proteinuria

Which renal condition leads to reabsorption droplets in tubule cells?

Neurofibrillary tangles

Which protein aggregates are found in Alzheimer’s disease?

Amyloidosis

Which protein-aggregation disease involves extracellular fibril deposits?

Hyaline change

What non-specific alteration gives cells a glassy pink appearance on H&E?

PAS stain

Which stain highlights glycogen as rose-violet granules in tissues?

Diastase digestion

Which enzyme treatment confirms glycogen by removing it before staining?

Lipofuscin

Which wear-and-tear pigment accumulates with age but is non-injurious?

Melanin

Which endogenous brown-black pigment is synthesized from tyrosine?

Homogentisic acid

Which pigment accumulates in connective tissues in alkaptonuria?

Hemosiderin

Which iron-storage pigment forms in response to hemorrhage or overload?

Hemosiderosis

What condition results from systemic iron overload with organ deposition?

Dystrophic calcification

Which type of calcium deposition occurs in dead or dying tissues?

Metastatic calcification

Which type of calcification occurs in normal tissue with hypercalcemia?

Psammoma bodies

Which calcified structures are found in meningioma and papillary thyroid carcinoma?

Asbestos bodies

Which dumbbell-shaped structures are seen in lungs of exposed individuals?

Hyperparathyroidism

What endocrine disorder causes hypercalcemia and metastatic calcification?

Vitamin D toxicity

Which vitamin-related disorder contributes to metastatic calcification?

Renal failure

Which condition leads to phosphate retention and secondary hyperparathyroidism?

Sarcoidosis

Which granulomatous disease increases vitamin D activation by macrophages?

Paget’s disease

Which bone disorder accelerates turnover and leads to hypercalcemia?

Alkaline compartments

What makes tissues like lungs and kidneys more prone to metastatic calcification?

IL-1

Which inflammatory cytokine is released during pyroptosis and causes fever?

Ferruginous bodies

What is another name for asbestos bodies due to their iron content?

Ischemia-reperfusion injury

Which paradoxical injury involves complement activation after oxygen restoration?

Myelin figures

What structures form from degenerating membranes during reversible injury?

Thrombospondin

Which membrane protein promotes recognition of apoptotic cells by phagocytes?

Smooth ER

Which liver organelle is responsible for converting chemicals into toxic metabolites?

Cyanide

Which poison inhibits cytochrome oxidase, halting oxidative phosphorylation?

Alcoholic hyaline

Which keratin filament accumulation is seen in hepatocytes of alcoholics?

Vimentin

Which intermediate filament is found in connective tissue cells?

Desmin

Which intermediate filament is specific to muscle cells?

Keratin

Which intermediate filament is found in epithelial cells?

Neurofilaments

Which intermediate filaments accumulate in neurodegenerative diseases?

Glial fibrillary acidic protein

Which intermediate filament is specific to astrocytes?

Glycogen

Which substance accumulates in renal tubules, hepatocytes, and beta-islet cells in diabetes?

Amyloid

Which pathologic protein shows apple-green birefringence on Congo red stain?

Proteasomes

Which cellular structures degrade ubiquitinated misfolded proteins?

Ubiquitin

Which small protein tags misfolded proteins for degradation?

Protein folding abnormalities

What shared pathogenic feature is seen in cystic fibrosis, Tay-Sachs, and Alzheimer’s disease?