ANATOMY

Detailed explanation-1: -The second phase is called expiration, or exhaling. When the lungs exhale, the diaphragm relaxes, and the volume of the thoracic cavity decreases, while the pressure within it increases. As a result, the lungs contract and air is forced out.

Detailed explanation-2: -Expiration (exhalation) is the process of letting air out of the lungs during the breathing cycle. During expiration, the relaxation of the diaphragm and elastic recoil of tissue decreases the thoracic volume and increases the intraalveolar pressure. Expiration pushes air out of the lungs.

Detailed explanation-3: -In exhalation, the diaphragm moves upward and the chest wall muscles relax, causing the chest cavity to get smaller and push air out of respiratory system through the nose or mouth.

Detailed explanation-4: -Physical Factors Affecting Ventilation The recoil of the thoracic wall during expiration causes compression of the lungs. Contraction and relaxation of the diaphragm and intercostals muscles (found between the ribs) cause most of the pressure changes that result in inspiration and expiration.

Detailed explanation-5: -Exhalation is a passive process because of the elastic properties of the lungs. During forced exhalation, internal intercostal muscles which lower the rib cage and decrease thoracic volume while the abdominal muscles push up on the diaphragm which causes the thoracic cavity to contract.