Chemical Injury (Cellular Level)

Question 1

Name seven categories of causes of cell injury. One example is toxic chemicals.

Answer 1

1. Anoxia
2. Immune & autoimmune mediated
3. Genetic abnormalities
4. Microbial agents
5. Nutritional deficiency
6. Physical agents (trauma, radiation, temperature)
7. Toxic chemicals

Question 2

Explain the difference between etiology and mechanism in cell injury.

Answer 2

Etiology: Cause
Mechanism: Pathogenesis

Question 3

Explain the mechanism of cellular ATP deficit caused by anoxia, carbon monoxide poisoning, and cyanide poisoning.

Answer 3

Anoxia: No O2 reaching lungs and RBC
Carbon monoxide poisoning: No O2 in hemoglobin
Cyanide poisoning: Blocks oxidative phosphorylation

Question 4

State the molecular mechanism for CCl4 toxicity, and explain why gut lining cells escape toxic effects of CCl4.

Answer 4

•	Enters parenchymal cells and during its metabolism it produces free radicals
      o	Lipid peroxidation
      o	Membrane damage
      o	Damage to ER
      o	Cell swelling 
•	Organs that are targeted
      o	Liver, most damage near central vein (no nuclei, pykontic nuclei, accumulation of fat)
      o	Kidney
      o	Lung

Question 5

State the critical feature of molecular structure of a free radical.

Answer 5

• Unpaired electron

Question 6

List an example of a poison that is made toxic by metabolic alteration.

Answer 6

• CCL4

* Benzopyrene

Question 7

List an example of a poison that does not require metabolic activation in order to become toxic.

Answer 7

• Strong acids
• Strong bases
• Heavy metals
• CO

Question 8

Define: xenobiotics, poison, centrilobular necrosis (liver), lipid peroxidation, antibiotic, antimetabolite, metabolic activation.

Answer 8

Xenobiotic: Foreign chemical
Poison: Causes illness or death
Centrilobular necrosis of liver: Necrosis around the central vein following congestion
Lipid peroxidation: Oxidative degradation of lipids caused by free radicals
Antibiotic: Toxic to microorganisms
Antimetabolite: Poisons that resemble normal metabolites

Question 9

Use the example of cis-platinum (a chemotherapeutic agent) in describing the various mechanisms of molecular damage/alterations that lead to cell death

Answer 9

• Pt forms covalent bonds with macromolecules i.e. DNA
• Trigger apoptosis
• Stops mitosis in the intestine ( shortened villi and dilated crypts)
• Renal failure (necrotic, neutrophils, wide lumens)