Question

Expiration invloves

• A. Relaxation of diaphragm and intercostal muscles
• B. Contraction of diaphragm and intercostal muscles
• C. Contraction of diaphragm muscles
• D. Contraction of intercostal muscles

Answer 1

The correct option is A Relaxation of diaphragm and intercostal muscles

When we breathe out, or exhale, diaphragm relaxes and moves upward into the chest cavity. The intercostal muscles between the ribs also relax to reduce the space in the chest cavity. Thus, it increases the air pressure among the lungs and it easily comes out of the lungs.