(anatomy) The passages, divided into an upper and a lower part, through which air enters and leaves the body, including the mouth, nose and nasal passages, pharynx, larynx, trachea, bronchi and conducting bronchioles, sometimes further including the respiratory bronchioles, alveolar ducts and alveoli.

(biochemistry) any of several coloured metal-containing protein pigments which combine reversibly with oxygen and which are found in the tissues of vertebrates and invertebrates and whose role is to transport oxygen

Any of the downstream bronchioles that already engage in blood-air gas exchange, in contrast to the upstream conducting-zone bronchioles that merely transport air.

plural of respiratory bronchiole

plural of respiratory rate

(anatomy) The system of organs serving for respiration.

(anatomy) The part of the respiratory tract consisting of trachea, bronchi, bronchioles and alveoli.

(anatomy) The part of the respiratory tract consisting of the nose, oral cavity, pharynx and larynx.

(virology) Any virus in genus Pneumovirus causing respiratory tract infections.

plural of respiratory syncytial virus