Mechanism of plasma membrane damage in ischemia

# The major mechanism of damage to plasma membrane in ischemia is:
A. Reduced intracellular pH
B. Increased intracellular accumulation of sodium
C. Increased Ca++ ions in the cytosol
D. Reduced aerobic respiration

The correct answer is C. Increased Ca++ ions in the cytosol.

The ion calcium is critical for cell damage. Influx of calcium acts as second messenger and activates wide spectrum of enzymes that destroy cellular organelles.

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Most reactive free radical

# Out of the various free radical species, the following radical is most reactive:
A. Super oxide (O2
B. Hydrogen peroxide (H2O2
C. Hydroxyl (OH-
D. Nitric oxide (NO)

The correct answer is C. Hydroxyl ion.

Important mechanism of cell injury is by damage to DNA, proteins, lipid membranes, and circulating lipids (LDL) by peroxidation caused by oxygen derived free radicals--super oxide anion (O2-), hydroxy radical (OH-), and hydrogen peroxide (H2O2). Hydroxyl ion is most reactive.

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Folic acid deficiency

# Folic acid deficiency is associated with administration of:
A. Phenytoin
B. Chloramphenicol
C. Isoniazide
D. Streptomycin

The correct answer is A. Phenytoin.

Folic acid deficiency can be caused by drugs that interfere with folate absorption or metabolism. Phenytoin, some other anticonvulsants, oral contraceptives, and isoniazide can cause Folic acid deficiency by interfering with Folic acid absorption. Other drugs such as methotrexate and, to a lesser extent, trimethoprim and pyrimethamine, inhibit dihydrofolate reductase and may result in a deficiency of folate cofactors and ultimately in megaloblastic anemia.

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Fracture of the tooth bearing segment

# The fracture of the tooth bearing segment of the mandible is:
a) Simple
b) Complex
c) Compound
d) Comminuted

The correct answer is C. Compound.

• Simple fracture includes linear fracture of condyle, coronoid ramus and edentulous body or mandible.

• Compound fracture include fractures of tooth bearing portions of mandible.

• Green stick fracture is a rare type of simple fracture and is found exclusively in children.

• Comminuted fracture are due to direct violence to mandible from penetrating sharp objects and missiles.

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