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Multiple Choice
Inspiration occurs as a result of which of the following processes?
A
Relaxation of the diaphragm and internal intercostal muscles
B
Decrease in thoracic cavity volume
C
Contraction of the diaphragm and external intercostal muscles
D
Contraction of the abdominal muscles
Verified step by step guidance
1
Understand the mechanics of inspiration: Inspiration is the process of drawing air into the lungs, which requires an increase in thoracic cavity volume to create a pressure gradient that allows air to flow in.
Identify the role of the diaphragm: During inspiration, the diaphragm contracts and moves downward, increasing the vertical dimension of the thoracic cavity.
Examine the role of external intercostal muscles: These muscles contract during inspiration, pulling the rib cage upward and outward, which increases the lateral and anterior-posterior dimensions of the thoracic cavity.
Clarify why relaxation of the diaphragm and internal intercostal muscles is incorrect: Relaxation of these muscles occurs during expiration, not inspiration, as they reduce thoracic cavity volume.
Explain why contraction of abdominal muscles is incorrect: Abdominal muscle contraction is typically associated with forced expiration, not inspiration, as it pushes the diaphragm upward to expel air from the lungs.