What cellular component is not present in the respiratory zone?

What cellular component is not present in the respiratory zone?

• A. Smooth muscle
• B. Alveolar macrophages
• C. Cartilage
• D. Pneumocytes

Answer: (C)

The respiratory zone is primarily composed of structures involved directly in gas exchange, which includes the alveoli and associated cells. In this context, cartilage is not present in the respiratory zone. Instead, the respiratory zone is characterized by the presence of alveoli and features such as smooth muscle, which can help regulate airflow, and pneumocytes, which are the cells that line the alveoli and are crucial for the exchange of oxygen and carbon dioxide. Alveolar macrophages are also found in the respiratory zone and play a vital role in immune defense by cleaning the alveoli of pathogens and debris. In contrast, the conducting zone, which includes larger airways, is where cartilage is present, providing structural support to the airway passages. Therefore, the absence of cartilage in the respiratory zone highlights the contrasting structural components necessary for their distinct functions in respiration.

The respiratory zone is primarily composed of structures involved directly in gas exchange, which includes the alveoli and associated cells. In this context, cartilage is not present in the respiratory zone. Instead, the respiratory zone is characterized by the presence of alveoli and features such as smooth muscle, which can help regulate airflow, and pneumocytes, which are the cells that line the alveoli and are crucial for the exchange of oxygen and carbon dioxide. Alveolar macrophages are also found in the respiratory zone and play a vital role in immune defense by cleaning the alveoli of pathogens and debris.

In contrast, the conducting zone, which includes larger airways, is where cartilage is present, providing structural support to the airway passages. Therefore, the absence of cartilage in the respiratory zone highlights the contrasting structural components necessary for their distinct functions in respiration.