Question

Arrange the following in the correct sequence of branching in conducting zone and respiratory zone of respiratory passage.
(A) Alveolar sacs
(B) Bronchi
(C) Bronchioles
(D) Trachea
(E) Alveolar ducts

• A. (C), (A), (E), (D), (B)
• B. (A), (D), (B), (C), (E)
• C. (B), (A), (D), (C), (E)
• D. (D), (B), (C), (E), (A)
• E.

Hint:

Always remember the branching order of respiratory system: Trachea → Bronchi → Bronchioles → Alveolar ducts → Alveolar sacs.

Answer 1

The Correct Option is D

Step 1: Initial pathway - Trachea.
Air enters the respiratory system via the trachea, the largest airway, supported by cartilage. The first structure identified is (D) Trachea.
Step 2: Bifurcation into bronchi.
The trachea bifurcates into the right and left primary bronchi, which then further divide into secondary and tertiary bronchi. Therefore, the second structure is (B) Bronchi.
Step 3: Progression to bronchioles.
Bronchi continue to subdivide into smaller, cartilage-free bronchioles, continuing the air conduction pathway. Thus, the third structure is (C) Bronchioles.
Step 4: Entry into the respiratory zone - alveolar ducts.
Bronchioles ultimately branch into alveolar ducts, which lead directly to the gas exchange regions. Thus, the fourth structure is (E) Alveolar ducts.
Step 5: Terminal structures - alveolar sacs.
Alveolar ducts terminate in alveolar sacs, which are collections of alveoli, the primary sites for gas exchange. Thus, the fifth and final structure is (A) Alveolar sacs.
Step 6: Summary of sequence.
The established sequence of branching is: (D) Trachea → (B) Bronchi → (C) Bronchioles → (E) Alveolar ducts → (A) Alveolar sacs.