Respiratory tract

The entire respiratory system through which air travels as we breathe in oxygen (O2) and breathe out carbon dioxide (CO2).

A graphic showing the upper respiratory tract: nasal cavity, pharynx, and larynx; and the lower respiratory tract: Trachea, primary bronchi and lungsThe nose and nasal cavity, mouth, throat, voice box, and upper windpipe or trachea together form the upper respiratory tract. The large air tubes or bronchi, smaller air tubes or bronchioles and lungs with millions of alveoli (air sacs) form the lower respiratory tract.

The SARS-CoV-2 virus enters the nose through inhalation and settles in the upper respiratory tract where it causes inflammation of the lining of the tract giving rise to early symptoms such as dry cough and fever.

Active SARS-CoV-2 infection is diagnosed using throat and nasal swabs which collect mucous secretions from the back of the nasal cavity and the throat. Sometimes the infection travels further down into the alveoli. People with moderate COVID-19 may have mild pneumonia. In some cases, the infection damages the walls of the alveoli, air sacs, causing them to fill up with fluid. This process stimulates a very strong immune response that leads to inflammation and can result in acute respiratory distress syndrome (ARDS).


Infectious Disease Respiration


Alveoli (singular: Alveolus)Dry coughFeverSARS-CoV-2SwabAcute Respiratory Distress Syndrome (ARDS)Respiratory distressRespiratory diseaseAirborne TransmissionCOVID-19