Respiratory bronchiole proceed into –
**Core Concept**
Respiratory bronchioles are small airways in the lungs that play a crucial role in the transition from conducting airways to respiratory units. They are characterized by the presence of alveoli, which facilitate gas exchange between the lungs and the bloodstream.
**Why the Correct Answer is Right**
Respiratory bronchioles are part of the terminal bronchiole's continuation, where the airway diameter decreases, and the number of smooth muscle cells increases, making it more sensitive to bronchoconstrictors. This leads to a gradual transition from conducting airways to respiratory units, ultimately resulting in the formation of alveolar ducts and sacs. The respiratory bronchioles' primary function is to facilitate gas exchange, which is essential for the oxygenation of the blood.
**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because terminal bronchioles are characterized by a lack of alveoli and a relatively large diameter compared to respiratory bronchioles.
**Option B:** This is incorrect because the bronchioles are part of the conducting airways, which do not participate in gas exchange.
**Option C:** This is incorrect because respiratory bronchioles are not directly involved in the production of surfactant, which is primarily a function of type II pneumocytes in alveolar type II cells.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the respiratory bronchioles are the smallest airways that participate in gas exchange, and their dysfunction can lead to conditions such as bronchiolitis or bronchiolitis obliterans.
**Correct Answer: C. Alveolar ducts and sacs.**