PATHOLOGY MCQ
RESPIRATORY SYSTEM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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the volume of the thoracic cavity increases and the pressure decreases, causing air to rush into the lungs.
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the volume of the thoracic cavity decreases and the pressure increases causing air to rush out of the lungs.
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Either A or B
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None of the above
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Detailed explanation-1: -The second phase is called expiration, or exhaling. When the lungs exhale, the diaphragm relaxes, and the volume of the thoracic cavity decreases, while the pressure within it increases. As a result, the lungs contract and air is forced out.
Detailed explanation-2: -During expiration, the diaphragm relaxes, bowing up into the thoracic cavity, thereby decreasing the volume of the thoracic cavity. This results in a corresponding increase in pressure (Boyle’s law), and thus the movement of air from the lungs out of the body through the upper respiratory structures.
Detailed explanation-3: -During expiration, the relaxation of the diaphragm and elastic recoil of tissue decreases the thoracic volume and increases the intraalveolar pressure. Expiration pushes air out of the lungs.
Detailed explanation-4: -Lung volume expands because the diaphragm contracts and the intercostals muscles contract, thus expanding the thoracic cavity. This increase in the volume of the thoracic cavity lowers pressure compared to the atmosphere, so air rushes into the lungs, thus increasing its volume.