MICROANATOMY

Detailed explanation-1: -Quiet expiration is a passive process occurring at rest, whereas forced expiration is an active process that occurs during exercise. Quiet respiration depends on elastic recoil of the lungs after inspiratory stretching, elastic recoil of the costal cartilages, and the relaxation of the inspiratory muscles.

Detailed explanation-2: -Expiration is generally a passive event brought about by relaxation of the diaphragm and external intercostal muscles. The ribcage, diaphragm and lung tissue itself return by elastic recoil to their original pre-inspiratory positions. The consequent retraction of the chest wall forces air out of the lungs.

Detailed explanation-3: -Expiration. In healthy people quiet expiration or exhalation is passive and relies on elastic recoil of the stretched lungs as the inspiratory muscles relax, rather than on muscle contraction.

Detailed explanation-4: -To return to atmospheric pressure, air rushes into the lungs. The external intercostal muscles also contract during inspiration. Because this process requires the use of energy, quiet inspiration (inspiration during normal breathing) is an active process.

Detailed explanation-5: -Expiration is a normal passive process that involves relaxation of inspiratory muscles.