Need an easier read? Change your font
Anatomy Insight | Comic Sans | Lexend
Embedded Files
Lungs: Location, Structure & Function
Lungs: Location, Structure & Function
Includes labeled diagrams, downloadable notes, anatomy quizzes, and interactive learning tools
The lungs are paired, cone-shaped organs of respiration located within the thoracic cavity on either side of the mediastinum. They are soft, porous, elastic, and spongy in texture because of the air contained within the alveoli. Each lung has an apex extending above the clavicle into the root of the neck, a concave base resting on the diaphragm, a costal surface facing the ribs, and a mediastinal surface facing the heart and mediastinum.
The mediastinal surface contains the hilum, where bronchi, pulmonary arteries, pulmonary veins, lymphatics, and nerves enter or leave the lung to form the root of the lung. The lungs are covered by visceral pleura and separated from the thoracic wall by the pleural cavity containing pleural fluid.
Right Lung
The right lung is larger, broader, heavier, and more voluminous than the left lung, although it is slightly shorter because the diaphragm rises higher on the right side due to the liver.
It is divided into three lobes (superior, middle, and inferior) by two fissures: an oblique fissure and a horizontal fissure. The middle lobe is the smallest lobe.
On the mediastinal surface are grooves for the superior vena cava, azygos vein, esophagus, and inferior vena cava.
The right bronchus is shorter, wider, and more vertical than the left, making inhaled foreign bodies more likely to enter it. Before entering the lung, it gives off the eparterial bronchus to the superior lobe above the pulmonary artery.
The remaining bronchi are hyparterial. At the root of the right lung, the arrangement from above downward is: eparterial bronchus, pulmonary artery, hyparterial bronchus, and pulmonary veins.
The left lung is narrower, somewhat longer, and smaller in volume because the heart projects toward the left side.
It is divided into two lobes (superior and inferior) by a single oblique fissure. The anterior border contains the cardiac notch, which accommodates the heart, and below this is a tongue-like projection of the upper lobe.
The mediastinal surface shows impressions from the heart, aortic arch, descending aorta, subclavian artery, and esophagus.
The left bronchus is longer, narrower, and more horizontal than the right. All branches of the left bronchus are hyparterial because the pulmonary artery lies above them.
At the root of the left lung, the arrangement from above downward is: pulmonary artery, bronchus, and pulmonary veins.
Bronchial Tree and Lung Structure
Within the lungs, the bronchi branch repeatedly into smaller bronchi and bronchioles to form the bronchial tree. Cartilage rings become irregular cartilaginous plates in smaller bronchi and disappear in bronchioles under 1 mm in diameter. The lungs are divided into bronchopulmonary segments supplied by tertiary bronchi, and further into pulmonary lobules containing bronchioles and alveoli.
Blood Supply and Function
The lungs are specialized for gas exchange. Pulmonary arteries carry deoxygenated blood to capillary networks surrounding the alveoli, where oxygen enters the blood and carbon dioxide leaves it. Oxygenated blood returns to the heart through the pulmonary veins. The respiratory membrane formed by alveolar and capillary walls provides a large surface area for efficient gas exchange.
Pleura and Innervation
Each lung is enclosed within a pleural sac composed of visceral and parietal pleura. The pleural cavity between them contains pleural fluid that reduces friction and helps keep the lungs expanded during breathing.
The lungs receive autonomic innervation through the pulmonary plexus. Parasympathetic stimulation causes bronchoconstriction, while sympathetic stimulation causes bronchodilation.
Need a recap? Take a look at the lungs anatomy notes here.
Need a recap? Take a look at the lungs anatomy notes here.
Ready to test what you've learned?
Play through the games below to test your understanding and sharpen your skills.
References
References
Gray, H. (1918). Anatomy of the human body (W. H. Lewis, Ed.; 20th ed.). Lea & Febiger.
Sobotta, J. (1906). Atlas and text-book of human anatomy (J. P. McMurrich, Ed.; W. H. Thomas, Trans.). Vol. 2. W.B. Saunders Company.
J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix. (2013, April 25). Anatomy and Physiology. OpenStax. https://openstax.org/books/anatomy-and-physiology-2e/pages/13-2-the-central-nervous-system.
Based on OpenStax, Anatomy and Physiology (2013), licensed under CC BY 4.0.
Access for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction.
Content paraphrased; adaptations were made.
Image Credis
Image Credis
Images used in this guide and games are by Dr. Johannes Sobotta. They are in the public domain; modifications have been made to the originals.
Google Sites
Report abuse