Question

The gaseous exchange between blood and air does not occur in

• A. Conductive zone
• B. Respiratory zone
• C. Transitory zone
• D. All of the above

Answer 1

Answer: (A)

Conductive zone

The gaseous exchange between blood and air does not occur in the conductive zone. In the conductive zone, the gas exchange does not occur between blood and air. The respiratory and transitory zones including alveoli constitute about 90% of the lung volume. The conducting zone of the respiratory system is made up of the nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles; their function is to filter, warm, and moisten air and conduct it into the lungs. Thus, conducting zone + respiratory zone = respiratory tract (airway).

The respiratory zone is found deep inside the lungs and is made up of the respiratory bronchioles, alveolar ducts, and alveoli. The respiratory zone is the site of O2 and CO2 exchange with the blood. Thus, the correct answer is option A.