Respiratory Physiology: Hemoglobin

Question

A woman dumped a bucket of ice water over her head to raise global awareness about a neurological disease called amyotrophic lateral sclerosis, ALS. Which of the following correctly describes what happens in her body immediately afterward before thermoregulation?

a. Hb has a lower affinity for O₂; more O₂ is delivered to the tissues

b. Hb has a higher affinity for O₂; less O₂ is delivered to the tissues

c. Hb has a lower affinity for O₂; less O₂ is delivered to the tissues

d. Hb has a higher affinity for O₂; more O₂ is delivered to the tissues

[Hint: Apply knowledge of Hemoglobin Dissociation Curves]

Answer 1

B. Hb has a higher affinity for O2; less O2 is delivered to the tissues

The woman decreased her body temperature by dumping ice water over her head. Lower temperature increases Hb affinity for O2, so less O2 will be released into the tissues.

Remember the Hb-O2 dissociation curves. Decreased temperature induces a left shift of the curve, causing hemoglobin to have a higher affinity for O2. Other factors that induce a left shift are low CO2, high pH, and CO. Hemoglobin has a higher affinity for O2 in the lungs as well, as it acts like an acid in the lungs from the Haldane effect.

If I could, I would attach a diagram to show this visually, but there is no attachment option: