Question

Presence of large number of alveoli around alveolar ducts opening into bronchioles in mammalian lungs is

• A. Inefficient system of ventilation with litle of residual air
• B. Inefficient system of ventilation with high percentage of residual air
• C. An efficient system of ventilation with no residual air
• D. An efficient system of ventilation with little residual air

Answer 1

The correct option is D An efficient system of ventilation with little residual air

Alveoli is a characteristic feature of mammalian lungs. The pulmonary alveoli form the terminal ends of the respiratory tree and from these the branches out the alveolar sacs and ducts which act as efficient sites for gaseous exchange. These air sacs provide the total surface area of about 75 m${}^2$ Besides the epithelial layer and extracellular matrix, these contain collagen and elastic fibers. which stretch as the alveoli are filled with air and spring back to expel carbon dioxide during exhalation.

So, the correct answer is option D.