Multiple Choice
What role do red blood cells (erythrocytes) play in respiration?
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17. The Blood
Erythrocytes: Hemoglobin
Multiple Choice
In the context of erythrocytes and hemoglobin, how does carbon monoxide (CO) affect a smoker's blood oxygen-carrying capacity?
A
CO binds to hemoglobin with high affinity, forming carboxyhemoglobin and reducing the amount of hemoglobin available to carry
B
CO is rapidly converted to in erythrocytes, which directly increases hemoglobin saturation with
C
CO binds primarily to the heme iron and increases hemoglobin's ability to carry , raising blood oxygen content
D
CO binds to plasma proteins rather than hemoglobin, so it has minimal effect on transport by erythrocytes
Verified step by step guidance1
Understand that hemoglobin in erythrocytes carries oxygen (O_2) by binding it to the iron in the heme groups.
Recognize that carbon monoxide (CO) has a much higher affinity for hemoglobin than oxygen does, meaning CO binds more strongly to the heme iron than O_2.
When CO binds to hemoglobin, it forms carboxyhemoglobin, which reduces the number of available binding sites for oxygen on hemoglobin molecules.
This binding decreases the overall oxygen-carrying capacity of the blood because fewer hemoglobin molecules are free to transport oxygen to tissues.
Additionally, the presence of CO shifts the oxygen-hemoglobin dissociation curve to the left, making it harder for oxygen to be released from hemoglobin to the tissues.
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