Answer:
The prime agonist of inspiration is the diaphragm muscle.
The conditions when expiration becomes an active process is : Emphysema, Pneumonia, Bronchitis.
-Expiration is the passive process as there is elastic recoil of lungs following inspiration without contraction of any muscles.
-The elastic fibers in alveoli are damages or filled with mucus and fluid in the disease such as conditions such as emphysema or pneumonia.
-Elastic recoil of lungs.
-Hence, muscle contraction is required to forcefully exhale the air from lungs. Internal intercostal muscles contract to pull the ribs downward and remove air from the lungs.
