Which statement best describes the health effects mechanism of carbon monoxide?

Which statement best describes the health effects mechanism of carbon monoxide?

• A. It forms carboxyhemoglobin reducing oxygen delivery
• B. It increases oxygen carrying capacity
• C. It has no effect on the nervous system
• D. It causes direct chemical burns on lungs

Answer: (A)

Carbon monoxide causes harm mainly by binding tightly to hemoglobin to form carboxyhemoglobin, which markedly reduces oxygen delivery to tissues. CO has a much higher affinity for hemoglobin than oxygen, so it displaces O2 and lowers overall oxygen carrying capacity; this also shifts the oxygen-hemoglobin dissociation curve to the left, making it harder for the remaining oxygen to be released to cells. While CO can also affect cellular respiration by interacting with other heme-containing proteins, the dominant effect is tissue hypoxia due to carboxyhemoglobin formation. The idea that CO would increase oxygen capacity, leave the nervous system untouched, or burn lung tissue directly does not describe how it causes damage.

Carbon monoxide causes harm mainly by binding tightly to hemoglobin to form carboxyhemoglobin, which markedly reduces oxygen delivery to tissues. CO has a much higher affinity for hemoglobin than oxygen, so it displaces O2 and lowers overall oxygen carrying capacity; this also shifts the oxygen-hemoglobin dissociation curve to the left, making it harder for the remaining oxygen to be released to cells. While CO can also affect cellular respiration by interacting with other heme-containing proteins, the dominant effect is tissue hypoxia due to carboxyhemoglobin formation. The idea that CO would increase oxygen capacity, leave the nervous system untouched, or burn lung tissue directly does not describe how it causes damage.