The primary function of the respiratory system is to facilitate the exchange of oxygen and carbon dioxide between the body and the environment.

The heart is part of the cardiovascular system, not the respiratory system.

Oxygen moves from the lungs to the bloodstream by diffusion, a process in which molecules move from an area of high concentration to an area of low concentration.

The diaphragm is the main muscle involved in breathing. It contracts and relaxes to change the volume of the thoracic cavity, causing air to flow in and out of the lungs.

Pneumonia is the inflammation of the lungs, usually caused by an infection.

Bronchitis is the inflammation of the bronchi, the airways that carry air to and from the lungs.

Asthma is a chronic respiratory disease characterized by wheezing, coughing, and shortness of breath.

Emphysema is a chronic respiratory disease characterized by the destruction of lung tissue, causing shortness of breath and difficulty breathing.

Respiratory distress syndrome is a condition in which the lungs do not produce enough surfactant, a substance that helps the lungs expand and contract.

Pulmonary edema is a condition in which the lungs fill with fluid, causing shortness of breath and difficulty breathing.

Atelectasis is a condition in which a portion of the lung collapses, causing shortness of breath and difficulty breathing.

Pneumothorax is a condition in which air leaks into the pleural space, the space between the lungs and the chest wall, causing shortness of breath and chest pain.

Lobectomy is a surgical procedure in which a portion of the lung is removed, typically to treat lung cancer or other lung diseases.

Pneumonectomy is a surgical procedure in which the entire lung is removed, typically to treat lung cancer or other lung diseases.

Thoracotomy is a surgical procedure in which the chest cavity is opened, typically to perform lung surgery or to treat other conditions affecting the chest.

Bronchoscopy is a procedure in which a thin, flexible tube is inserted into the airways to examine the lungs, typically to diagnose or treat lung diseases.