Structure of respiratory system Divided into two parts Upper respiratory- nose, nasal cavity, pharynx, u Lower respiratory- trachea, larynx, trachea, bronchi, alveoli and Diaphragms Various protective components- ciliated mucous membrane, alveolar macrophage and secretory antibodies. Microbiome of upper respiratory system Upper respiratory system Colonized by many microorganisms. Normal microbiome limits growth of pathogens. Normal microbiome may be opportunistic pathogens. Bacterial disease of the upper respiratory system, sinuses, and ears Streptococcal respiratory disease Signs and symptoms Pharyngitis Sore throat and difficulty swallowing.