bronchus. medical depicting respiratory cilia and mucus. pseudostratified columnar epithelium. structure

bronchus medical illustration depicting respiratory cilia mucus pseudostratified columnar epithelium structure ciliated infographic anatomy branchial wall crossection system mucociliary escalator goblet cells concept model trachea pulmonary diagram education body respiration science healthy anatomical medicine lung microbe airways cell secrete protect microorganism bronchi health internal infection hum