longen

Longen, the Dutch term for lungs, are a pair of spongy, air-filled organs that facilitate gas exchange in most air-breathing vertebrates. In humans, they reside in the thoracic cavity and are separated by the mediastinum. Each lung contains a branching system of air passages—the bronchial tree—leading to tiny air sacs called alveoli, where oxygen passes into the blood and carbon dioxide is released for exhalation.

Anatomy: The right lung has three lobes (upper, middle, lower) and the left lung has two (upper, lower) with a cardiac notch to accommodate the heart. The lungs are enveloped by a double-layered pleural membrane and are supplied by the pulmonary arteries and drained by pulmonary veins; the bronchial circulation also nourishes lung tissue.

Physiology: Gas exchange occurs across the alveolar-capillary membrane. The lungs ventilate via rhythmic movements of the diaphragm and intercostal muscles, creating negative intrapleural pressure that draws air in. Surfactant reduces surface tension in the alveoli, helping keep them open.

Development: In embryology, lung tissue arises from foregut endoderm with mesoderm forming bronchial structures, vasculature, and pleura.

Clinical relevance: Common conditions include infections such as pneumonia, chronic obstructive pulmonary disease, asthma, pulmonary embolism, and lung cancer. Diagnostics include chest imaging and pulmonary function tests.

Terminology: In Dutch-language medicine, longen refers to the lungs; the term is used across anatomy, physiology, and clinical contexts.