Human upper body with brain, (upper and lower) airways, as well as oral cavity, nasopharyngeal space, trachea, bronchi and lung as well as inner organs of the lower abdomen (gastrointestinal tract). The yellow areas are supplied with air. It becomes obvious, that ventilation of the lung happens mostly in the upper sections. A virus next to the body. Airway disease as a collective term for feverish diseases with catarrh of the upper airways caused by viruses. Their symptoms are similar to the course of the real flu.