The upper airways:
The upper airways serve as the point of entry to the airways as a whole. It is divided into three areas, which work closely together in many ways:
The nose with the paranasal cavities (the maxillary sinuses, frontal sinus, sphenoid sinus and the ethmoidal cells), the pharynx, and the larynx. The upper airways are coated with a layer of mucus.
Diseases of the nose (rhinitis), the paranasal cavities (acute and chronic sinusitis), the pharynx (pharyngitis) and the larynx (laryngitis, pseudocroup) can be caused by viral or bacterial pathogens, or they can also take the form of an allergic reaction.
The lower airways:
The lung consists of the trachea, bronchial system (bronchi and bronchioles) as well as the air cells of the lung (alveoli). It can be divided into a central, middle and outer area.
Diseases affecting the lung include coughs,bronchitis, pneumonia, asthma, COPD and cystic fibrosis.