Lung
The lungs are a pair of spongy, air-filled organs located on either side of the chest that are essential for breathing and gas exchange. They take in oxygen from the air and expel carbon dioxide, a waste product of metabolism, helping to maintain the body’s internal chemical balance. Each lung is divided into lobes—three on the right and two on the left—and is protected by the ribcage and enclosed in a thin membrane called the pleura, which also helps reduce friction during breathing.
Air enters the lungs through the respiratory tract, beginning at the nose or mouth and continuing down the trachea, which branches into the bronchi and then into smaller bronchioles that terminate in microscopic air sacs called alveoli. These alveoli are surrounded by tiny blood vessels where oxygen passes into the bloodstream and carbon dioxide is removed. This gas exchange process is critical for supplying oxygen to organs and tissues and for removing carbon dioxide from the body.
Breathing is controlled by the respiratory center in the brainstem, which sends signals to the diaphragm and other muscles to expand and contract the lungs. This automatic process adjusts in response to the body’s oxygen demands, such as during exercise, sleep, or stress. The lungs also play secondary roles in regulating blood pH, filtering small blood clots, and metabolizing certain substances in the blood.
Lung health is vital for overall well-being. Diseases such as asthma, chronic obstructive pulmonary disease (COPD), pneumonia, pulmonary fibrosis, and lung cancer can impair breathing and oxygen delivery. Environmental factors like air pollution, smoking, and occupational exposure to harmful particles are major contributors to lung disease. Ongoing research into respiratory biology and treatment is helping to improve outcomes for individuals with lung conditions, underscoring the importance of the lungs in sustaining life.