Question

Which features distinguish bronchioles from bronchi?
A. Bronchioles are less than 1mm in diameter.
B. Bronchioles have cartilage in their walls.
C. Larger bronchioles are supported by connective tissue along which extend from the interlobular septa.
D. Both A and B
E. Both A and C

Answer 1

Hint: When we breathe in air, the air travels down through our windpipe(trachea). It then moves towards our lungs. These tubes are known as bronchi. When air enters from the windpipe towards lungs with the help of the tube called bronchi is further branched into very smaller and smaller pipes or tubes called bronchioles.

Complete answer:
There is no cartilage in the bronchioles along with their very small size that can be distinguished from bronchi. Bronchioles are approximately 1mm or can be even less than 1mm. The bronchi is also called the primary bronchi, in each lung. These rise to tertiary bronchi (tertiary meaning "third"), known as segmental bronchi. These are different from the bronchi in that their walls do not have cartilage and they have cells in their epithelial lining. The diameter of the bronchioles is often said to be less than 1 mm, though this can range from 5 mm to 0.3 mm. As stated, these bronchioles do not have cartilage to maintain their patency. Instead, they depend on elastic fibres attached to the surrounding lung tissue for support. As the bronchioles will get smaller they divide into terminal bronchioles. Each bronchiole divides into between 50 and 80 terminal bronchioles. These bronchioles mark the end of the conducting zone, which covers the first division through the sixteenth division of the respiratory tract.

Hence, the correct answer is option (A)

Note: Alveoli only become present when the conducting zone changes to the respiratory zone, from the sixteenth through the twenty-third division of the tract. They do not contain the cartilage; it is only found in the bronchi.