lungsystemet

The lungsystemet, or the respiratory system, is the collection of organs and structures responsible for bringing air into the body, exchanging oxygen and carbon dioxide, and expelling air. It supports cellular metabolism by supplying oxygen and removing waste products.

Anatomy: The main components are the airways, the lungs, the pleural membranes, and the breathing muscles. Air enters through the nose or mouth, passes down the trachea, and branches into the two main bronchi, then into progressively smaller bronchioles ending in alveolar sacs. The lungs are divided into lobes (the right lung has three lobes and the left lung has two). The pleura encloses the lungs and forms a sealed thoracic cavity with the diaphragm and intercostal muscles enabling ventilation.

Physiology: Ventilation involves inspiration and expiration. Inhalation expands the thoracic cavity, drawing air into the lungs; exhalation restores volume and expels air. Gas exchange occurs in the alveoli, where oxygen diffuses into the blood and carbon dioxide diffuses into the air. Oxygen is transported mainly by hemoglobin in red blood cells; carbon dioxide is carried mostly as bicarbonate in plasma. The process is regulated by the brainstem and chemoreceptors that adjust rate and depth in response to carbon dioxide, oxygen, and pH levels.

Clinical notes: The lungsystemet is commonly affected by diseases such as asthma, chronic obstructive pulmonary disease (COPD), pneumonia, pulmonary fibrosis, and lung cancer. Protective mechanisms include mucociliary clearance, immune defenses, and surfactant that reduces surface tension in the alveoli. Environmental factors like tobacco smoke and air pollution can impair lung function over time.