bronkialträdets

The bronchial tree, also known as the tracheobronchial tree, refers to the branching network of airways in the respiratory system that conducts air from the trachea into the lungs. It begins with the trachea, which then divides into the left and right primary bronchi. These primary bronchi further subdivide into progressively smaller tubes called bronchioles. The branching pattern is extensive, with each generation of bronchioles becoming narrower and thinner-walled.

The initial divisions of the bronchial tree, the primary, secondary (lobar), and tertiary (segmental) bronchi, are characterized by cartilage in their walls, providing structural support. As the airways continue to branch into smaller bronchioles, cartilage gradually disappears, and smooth muscle becomes more prominent. This smooth muscle allows for regulation of airway diameter.

The terminal bronchioles represent the end of the conducting zone, where air is warmed, humidified, and filtered. Beyond the terminal bronchioles lie the respiratory bronchioles, which are the first part of the respiratory zone, where gas exchange begins to occur. These then lead into alveolar ducts, alveolar sacs, and finally, the alveoli, which are the tiny air sacs where the majority of oxygen and carbon dioxide exchange takes place with the bloodstream. The extensive surface area of the alveoli is crucial for efficient respiration. The entire bronchial tree is lined with ciliated epithelium and goblet cells, which help trap and remove foreign particles and mucus.