Which of the following is the last step that produces an inspiration?
A)The atmospheric pressure becomes lower than the intrapleural pressure.
B)The diaphragm contracts.
C)The intercostal muscles contract.
D)The intra-alveolar pressure becomes lower than the atmospheric pressure.
E)The intrapleural pressure becomes positive.

Question

Quizplus · Accepted Answer

Inspiration occurs when the intra-alveolar pressure becomes lower than the atmospheric pressure, allowing air to flow into the lungs. This is accomplished by the contraction of the diaphragm and the intercostal muscles, which increase the volume of the thoracic cavity and decrease intra-alveolar pressure. Option A is incorrect because a decrease in atmospheric pressure does not directly cause inspiration. Option B and C are steps that lead to lung expansion but not the last step in producing an inspiration. Option E is incorrect because a positive intrapleural pressure would impede lung expansion and not produce inspiration.

Which of the Following Is the Last Step That Produces