Exchange of gases between the air spaces of the lungs and the blood in the pulmonary capillaries. Pulmonary blood gains oxygen and loses carbon dioxide
Large cavity in the anterior aspect of the skull that lies inferior to the nasal bone and superior to the mouth, it also includes muscle and mucous membrane
Cup shaped outpouching lined by simple squamous epithelium
2 types of alveolar epithelial cells: Type 1 (main site of gas exchange, simple squamous), Type 2 (septal cells, rounded or cuboidal with microvilli, secrete alveolar fluid, keeps normal moisture of air)
Breathing in, inhalation, just before each inspiration the air pressure in the lungs is equal to the pressure of the atmosphere, for air to flow in the lungs the pressure inside the alveoli must become lower than the environment - achieved by increasing the volume of the lung
Breathing out, exhalation, the pressure of the lungs is greater than the pressure of the atmosphere, passive process with no muscular contractions, results from elastic recoil of chest wall and lungs