Question

Arrange the following structures in the order air passes through them during inhalation.

(1) alveolar ducts
(2) alveolus
(3) respiratory bronchiole
(4) terminal bronchiole

A) 4, 3, 1, 2
B) 3, 4, 1, 2
C) 4, 3, 2, 1
D) 3, 4, 2, 1

Answer 1

The correct order is Terminal bronchiole (4), Respiratory bronchiole (3), Alveolar ducts (1), Alveolus (2), represented by option A) 4, 3, 1, 2. This sequence starts with the smallest non-respiratory airways (terminal bronchioles) and ends at the alveoli where gas exchange occurs.

Step-by-step explanation:

The correct order in which air passes through the structures during inhalation from the terminal bronchiole to the alveolus is A) 4, 3, 1, 2. This sequence is as follows:

1. Terminal bronchiole - the smallest airways within the lungs that are not involved in gas exchange.
2. Respiratory bronchiole - these are the first airways that are part of the respiratory system where gas exchange can occur.
3. Alveolar ducts - the ducts lead directly to the alveolar sacs, linking the respiratory bronchioles to the alveoli.
4. Alveolus - the tiny air sacs where the gas exchange between air and blood occurs.

As air flows into the lungs during inhalation, it moves through the trachea to the primary bronchi and continues to divide into smaller bronchi and then into bronchioles. The terminal bronchioles are the last non-respiratory airways before the air reaches the respiratory bronchioles, proceeding to the alveolar ducts which are connected to alveolar sacs containing alveoli for gas exchange.