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Multiple Choice
Which events occur during quiet inhalation?
A
The diaphragm contracts and moves downward, increasing thoracic volume.
B
The intercostal muscles contract, decreasing thoracic volume.
C
The abdominal muscles contract, pushing the diaphragm upward.
D
The diaphragm relaxes and moves upward, decreasing thoracic volume.
Verified step by step guidance
1
Understand the process of quiet inhalation: Quiet inhalation is a passive process primarily driven by the diaphragm and intercostal muscles.
Identify the role of the diaphragm: During quiet inhalation, the diaphragm contracts and moves downward, which increases the volume of the thoracic cavity.
Recognize the role of the intercostal muscles: The external intercostal muscles contract, lifting the ribs upward and outward, further increasing the thoracic volume.
Consider the effect on thoracic volume: As the thoracic volume increases, the pressure inside the thoracic cavity decreases, allowing air to flow into the lungs.
Clarify the incorrect options: The abdominal muscles do not contract during quiet inhalation, and the diaphragm does not relax and move upward during this phase.