11. The bronchioles ( small airways ) fill up with mucus leading to laboured breathing. 12. There are usually three arteries, and they branch alongside the bronchi and bronchioles . 13. These bronchioles give rise to the air sacs in the lungs called the alveoli. 14. Bronchioles possess the same columnar epithelial lining, but are not surrounded by cartilage rings.15. Lung parenchyma is the substance of the lung outside of the alveoli and respiratory bronchioles . 16. The same goes for goblet cells, although there are scattered ones in the first bronchioles . 17. Levosalbutamol relaxes the smooth muscles of all airways, from the trachea to the terminal bronchioles . 18. If the bronchiole is completely obstructed, atelectasis occurs : the alveoli of the lung collapse. 19. But the infection can then move into the lower respiratory tract-- the bronchioles and lungs. 20. The lobes of the lungs are further divided into bronchopulmonary segments based on the locations of bronchioles .
