The lungs are the largest and main organs of the respiratory system. Every person has one right and one left lung. They are located on both sides of the mediastinum in the thorax. The right lung is situated on the right side of the heart and the mediastinum, while the left lung is on the left side.

The main function of the lungs is to provide the external and internal respiration processes.

During external respiration, the lungs fill up with air inhaled from the environment. The gas exchange happens at the smallest structural and functional units of the respiratory system - alveoli. It occurs between the pulmonary capillaries containing carbon dioxide and air in the alveoli rich in oxygen. Once the exchange has occurred, the air now rich in carbon dioxide is released back into the external environment by exhalation. This entire process is also known as breathing.
During internal respiration, the gas exchange happens at the level of the body capillaries between blood that contains oxygen and body cells rich in carbon dioxide.

Each lung appears somewhat conical in shape with a rounded apex pointed upwards and a flat base directed downwards. The bases of the lungs rest on the convex domes of the diaphragm.

Also, each lung has several surfaces and borders, and tcontain fissures that divide the lungs into smaller sections known as the lobes. The lobes are further subdivided into bronchopulmonary segments.

Each lung has a pulmonary hilum through which various anatomical structures (major bronchi, blood vessels and nerves) enter and leave the lung via the root of the lung.

Neurovascular supply of lungs

The arterial blood supply and venous drainage of the lungs are provided by two circulation systems - bronchial and pulmonary.

The bronchial circulation is a part of the systemic circulation, and it is formed by the bronchial arteries and veins. The bronchial arteries provide oxygenated blood to the lungs, while the bronchial veins collect deoxygenated blood from the bronchi and hila of the lungs.
In contrast, pulmonary circulation is provided by the pulmonary arteries and veins. The pulmonary arteries receive deoxygenated blood from the right ventricle of the heart via the pulmonary trunk. In the lungs, deoxygenated blood becomes oxygenated, and it reaches the left atrium of the heart via four pulmonary veins.

The innervation of the lungs is provided by the vagus nerve (CN X) providing parasympathetic innervation, and nerve fibers arising from the cervical ganglia of the sympathetic trunk that provide sympathetic innervation. These nerves form two plexuses - anterior pulmonary plexus and posterior pulmonary plexus. (Learn more)

NOTE: For more detailed anatomy of the lungs and their neurovascular supply, please visit our 3D article "Lungs"!

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Lungs