respiratory

Respiratory refers to the process of breathing and the organs involved in gas exchange between the air and the bloodstream. In biology, respiration is commonly divided into the respiratory system and the gas-exchange processes that occur in the lungs.

The respiratory system includes the upper airways—nasal passages, mouth, pharynx, and larynx—and the lower airways, such as the trachea, bronchi, and bronchioles, culminating in the lungs. The lungs contain millions of tiny air sacs called alveoli where oxygen and carbon dioxide are exchanged. The diaphragm and intercostal muscles drive ventilation, the mechanical process of moving air in and out of the lungs.

Ventilation moves air to bring oxygen into the lungs and remove carbon dioxide from the bloodstream. Inhalation expands the chest cavity, lowering pressure to draw air in; exhalation reduces volume, pushing air out. In the alveoli, oxygen diffuses into the blood, while carbon dioxide diffuses from the blood into the alveolar space to be exhaled.

Oxygen is transported by red blood cells bound to hemoglobin, delivering it to tissues throughout the body. Carbon dioxide is carried back to the lungs as bicarbonate, dissolved CO2, or bound to hemoglobin, and is expelled during exhalation. Cellular respiration in body cells uses oxygen to produce energy, with carbon dioxide as a waste product.

Breathing is regulated mainly by the brainstem, with chemical receptors monitoring CO2, O2, and pH to adjust ventilation. Voluntary control can modify breathing patterns during activities such as speaking or breath-holding.

Healthy respiration supports efficient gas exchange; disorders such as infections, asthma, COPD, or restrictive diseases can impair ventilation or diffusion.