Question

At the beginning of inspiration, the

a. diaphragm relaxes
b. thoracic cavity volume increases
c. diaphragm becomes dome shaped
d. thoracic cavity pressure increases

Answer 1

During inspiration, the diaphragm contracts and the rib muscles contract, expanding the thoracic cavity and allowing air to rush into the lungs. During expiration, the diaphragm relaxes and the rib muscles relax, contracting the thoracic cavity and pushing air out of the lungs. Hence the correct answer is option C

Step-by-step explanation:

During inspiration, the diaphragm contracts and moves down, and the rib muscles contract, expanding the thoracic cavity. This increases the volume of the thoracic cavity and lowers the pressure compared to the atmosphere, allowing air to rush into the lungs. The diaphragm becomes dome-shaped at rest and relaxes during expiration when it expands and moves upwards, and the rib muscles relax, contracting the thoracic cavity and increasing the air pressure inside, which pushes the air out of the lungs.

Hence the correct answer is option C