What happens to the volume of the thorax and the air pressure in the lungs during breathing in?
Correct answer: E. Option E
- A. Option A
- B. Option B
- C. Option C
- D. Option D
- E. Option E
Explanation
During inspiration, contraction of the diaphragm causes its dome shape to flatten its dome shape whereas the contraction of the external intercostal and relaxation of the internal intercostal causes the Ribcage to move upward and forward. Both these events result in the increase of inner space of the thoracic cavity. Consequently, the pressure in the thorax and hence in the lungs is reduced to less than atmospheric pressure. As the pressure in the thorax decreases, its volume increases(NBF page 9). Thus, option E is the correct answer.
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About Respiration
The human respiratory system includes the air passages, lungs, alveoli and breathing muscles, while gaseous exchange explains how oxygen enters blood and carbon dioxide leaves it by diffusion. The effects of smoking include damage to cilia and alveoli, reduced gas exchange, chronic bronchitis, emphysema and increased risk of lung cancer.
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