Question

How is inhaled air modified before it reaches the lungs? a. It must be humidified. b. It must be warmed. c. It must be filtered. d. All of these are correct.

Short answer

Inhaled air is modified before it reaches the lungs by undergoing humidification, warming, and filtration. Therefore, the correct answer is (d) All of these are correct.

Step-by-step solution

1. Evaluate Answer Choice a

: Choice a states that inhaled air must be humidified. This is indeed a modification that occurs as air passes through the nose and nasal passages before reaching the lungs. The nasal passages add moisture (water vapor) to the air, which helps protect the delicate lung tissue from drying out.

2. Evaluate Answer Choice b

: Choice b states that inhaled air must be warmed. Similarly, the inhaled air is warmed as it passes through the nose and nasal passages. The heat comes from the blood vessels in the mucous membranes and helps to bring the air to body temperature, which is essential for proper gas exchange in the lungs.

3. Evaluate Answer Choice c

: Choice c states that inhaled air must be filtered. This is also true, as the nose and nasal passages have design features such as hairs and mucus to trap dust, pollen, and other particulates present in the air. The filtration process helps to prevent these particles from reaching the lungs and causing damage or infection.

4. Evaluate Answer Choice d

: Choice d states that all of these (a, b, and c) are correct. Since we have already determined that inhaled air undergoes humidification, warming, and filtration before reaching the lungs, this answer choice is the correct one.

5. Conclusion

: Thus, the correct answer is (d) All of these are correct, as inhaled air is humidified, warmed, and filtered before it reaches the lungs.