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The lungs are a pair of organs in the chest that play a crucial role in the respiratory system. They are responsible for the process of breathing, which involves the exchange of oxygen and carbon dioxide between the body and the external environment. Each lung is a spongy, cone-shaped organ that is divided into lobes, which are further subdivided into smaller units called bronchioles. The lungs are surrounded by a thin membrane called the pleura, which helps to protect and lubricate them.

The primary function of the lungs is to facilitate gas exchange. When a person inhales, air enters the lungs through the trachea and bronchi, and then into the bronchioles. The bronchioles are lined with tiny air sacs called alveoli, which are the site of gas exchange. Oxygen from the inhaled air diffuses into the bloodstream, while carbon dioxide, a waste product of cellular metabolism, diffuses from the bloodstream into the alveoli to be exhaled.

The lungs also play a role in the body's immune system. They contain a network of lymphatic vessels that help to filter out and remove foreign particles and pathogens from the air. Additionally, the lungs produce a substance called surfactant, which reduces the surface tension in the alveoli and helps to keep them open and elastic.

The lungs are susceptible to a variety of diseases and conditions, including pneumonia, asthma, chronic obstructive pulmonary disease (COPD), and lung cancer. These conditions can cause symptoms such as shortness of breath, coughing, and chest pain. Treatment options for lung diseases vary depending on the specific condition and its severity, and may include medications, surgery, or other interventions.