Biology – The gas exchange system | e-Consult

Answer: The wall of a bronchus, as seen in a cross-section, consists of the following layers, from inner to outer:

• Mucosa: The innermost layer, composed of pseudostratified columnar epithelium with cilia and goblet cells. Function: This layer secretes mucus to trap debris and pathogens, and the cilia move the mucus upwards towards the trachea for removal.
• Submucosa: A layer of connective tissue located beneath the mucosa. Function: Provides support and contains blood vessels and nerves that supply the mucosa.
• Cartilaginous Hoop: A ring of hyaline cartilage that provides structural support and prevents the bronchus from collapsing. Function: Maintains the patency of the airway.
• Adventitia (or Serosa): The outermost layer, composed of fibrous connective tissue. In the bronchus, this layer is referred to as the adventitia. Function: Attaches the bronchus to surrounding tissues and organs.