Carbon monoxide (CO) poisoning is a significant cause of mortality in the United States. Which of the following statements about CO is correct? A. competes with CO2 for a common binding site of hemoglobin B. competes with O2 for a common binding site of hemoglobin C. has a lower affinity for hemoglobin than does O2 D. irreversibly binds to hemoglobin E. is normally a perfusion- limited gas

• competes with O2 for a common binding site of hemoglobin

Explanation:

Carbon monoxide is lighter than air and has greater affinity for hemoglobin than oxygen does. Carbon monoxide displaces oxygen and quickly binds which means less oxygen can be transported to the cells whenever there is carbon monoxide inside the system. When cells lack oxygen, respiration stops and there is increased acidity in the cells, the body tissues and cells finally fail and die.