Suzy is a 14 year old with pulmonary fibrosis. This diseasecauses progressive scarring of the lungs and therefore, reducedinspiratory volumes and chronic hypoxemia. Suzy is veryinquisitive. Due to her disease, she knows that when she breathesin, her lungs help to bring oxygen into her blood, and when shebreathes out, she gets rid of carbon dioxide from her blood. At herappointment today, you note that she has cyanosis (blue coloration)and clubbing in her fingers and toes – symptoms of hypoxemia. WhenSuzy asks why her fingers and toes look the way they do, you tellher that she is not getting enough oxygen to them. This answer doesnot satisfy Suzy! She then asks:
1. “How EXACTLY does oxygen get into my blood and carbon dioxideget out of my blood when I breathe?†(How do I oxygenate myblood?)
2. “And how does the oxygen get from my blood into my toes andfingers so they won’t turn blue?†(How do I oxygenate mytissues?)
Be thorough (or Suzy will just keep asking “how…why?†She isannoying like that!)
For both 1 and 2: Be sure you describe the events in the correctsequence. Your answer should include the how each gas’s partialpressure affects its diffusion, and the chemical reactions thatoccur within the blood during gas exchange.
3. Concerned, the doctor asks you to determine Suzy’sinspiratory reserve volume (IRV). Using a spirometer, you measureher tidal volume (TV) at 100 mL, expiatory reserve volume (ERV) at800 mL, and her vital capacity (VC) at 1100 mL. What is herinspiratory reserve volume?
4. Finally, you treat Suzy by giving oxygen via a mask. Explainwhy this would be helpful in oxygenating her blood even though herinspiratory volumes are reduced.
