Chapter 13, Problem 1MC

More than one choice may apply.

When you exhale, air flows through respiratory structures in which sequence?

a. Alveolus, bronchiole, bronchus, larynx, trachea, pharynx, nasal cavity

b. Alveolus, trachea, bronchus, bronchiole, larynx, pharynx, nasal cavity

c. Alveolus, bronchus, bronchiole, trachea, larynx, pharynx, nasal cavity

d. Alveolus, bronchiole, bronchus, trachea, larynx, pharynx, nasal cavity

Summary Introduction

Introduction:

The respiratory system consists of a network of organs that work concertedly to bring about the gaseous exchange. It primarily involves two parallel processes namely inspiration (intake of gases) and expiration (exhalation of gases). These two processes help to maintain a proper gaseous homeostasis that is essential for the survival of an organism.

Answer to Problem 1MC

Correct answer:

Expiration begins at the gaseous exchange site of alveolus followed through bronchiole to bronchus, reaching to trachea then larynx, and is finally expired through nasal cavity through pharynx.

Explanation of Solution

Explanation for the correct answer:

Option (d) states the expiration route as alveolus, bronchiole, bronchus, trachea, larynx, pharynx, and nasal cavity. Expiration removes gases from the system and it follows the pathway governed by respiratory anatomy. The organ sequence in the respiratory anatomy in expiration is alveolus, bronchiole, bronchus, trachea, larynx, pharynx, and nasal cavity. Hence option (d) is correct.

Explanation for incorrect answers:

Option (a) mentions that the expiration occurs through larynx followed by trachea, which is incorrect because larynx lies downstream of trachea in expiration anatomy. So, it is an incorrect option.

Option (b) explains the expiration route through trachea followed by bronchus. This statement contradicts with the actual anatomical position of trachea, which is downstream of bronchus. So, it is an incorrect option.

Option (c) mentions that bronchus lie upstream of bronchioles in respiratory anatomy. The precise anatomical position of bronchus is downstream of bronchioles. So, it is also an incorrect option.

Hence, options (a), (b), and (c) are incorrect.

Conclusion

Expiration is involved in the removal of excessive gaseous materials from the body, which ensures that a balance between gaseous contents is maintained so, as to suit the physiology of an organism. The path of expiration is strictly under the control of respiratory anatomy and physiology.