Multiple Choice
Which of the following barriers must both \(\mathrm{O_2}\) and \(\mathrm{CO_2}\) cross to move between the air in the alveoli and the blood in pulmonary capillaries within the lungs?
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40. Circulatory System
Gas Exchange
Multiple Choice
What would most likely happen if the body allowed us to exhale all of the air out of our lungs during normal breathing?
A
The alveoli would collapse, making it difficult to reinflate the lungs.
B
The diaphragm would be unable to contract during the next inhalation.
C
Oxygen levels in the blood would rise above normal.
D
Gas exchange efficiency would increase significantly.
Verified step by step guidance1
Step 1: Understand the role of residual volume in the lungs. Residual volume is the amount of air that remains in the lungs after a normal exhalation. This air prevents the alveoli (tiny air sacs in the lungs) from collapsing completely, ensuring that the lungs can reinflate during the next inhalation.
Step 2: Consider the consequences of exhaling all air from the lungs. If the body allowed complete exhalation, the alveoli would collapse due to the lack of air pressure inside them. This would make it difficult for the lungs to reinflate during the next inhalation.
Step 3: Evaluate the role of the diaphragm in breathing. The diaphragm contracts during inhalation to create negative pressure in the chest cavity, drawing air into the lungs. If the alveoli collapsed, the diaphragm might struggle to create enough pressure to reinflate the lungs.
Step 4: Analyze the impact on oxygen levels and gas exchange. If the alveoli collapsed, gas exchange efficiency would decrease significantly because the surface area for oxygen and carbon dioxide exchange would be reduced. This would lower oxygen levels in the blood, not increase them.
Step 5: Conclude that the correct answer is related to alveolar collapse. The most likely outcome of exhaling all air from the lungs during normal breathing is that the alveoli would collapse, making it difficult to reinflate the lungs.
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