Cyanide poisoning and oxygen use
Cyanide blocks cytochrome c oxidase. What happens to the body's oxygen consumption and to venous blood oxygen levels?
Answer D: explanation for every choice
A
Venous oxygen falls when tissues extract more oxygen, the opposite of what happens here.
B
Rising oxygen consumption is the pattern of an uncoupler.
C
Blocking complex IV stops oxygen use, a major change.
D
Correct. Tissues can't use oxygen, so less is extracted from the blood, leaving venous blood unusually oxygen-rich.
TakeawayCyanide: cells can't use O2, so venous O2 stays high.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb119.