Question

when the inspiratory muscles contract,
multiple choice
expiration occurs.
thoracic volume decreases.
the alveolar pressure increases.
thoracic volume increases.
pleural pressure increases.

Explanation:

When inspiratory muscles (like the diaphragm and external intercostals) contract, they cause the thoracic cavity to expand. This expansion leads to an increase in thoracic volume. Expiration occurs when inspiratory muscles relax. When thoracic volume increases (due to muscle contraction), alveolar pressure decreases (as per Boyle's law: \(P \propto\frac{1}{V}\)), and pleural pressure (which is normally sub - atmospheric) becomes more negative (decreases further in a negative direction), not increases.

Answer:

thoracic volume increases.