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The human lungs flank the heart and great vessels in the chest cavity. Details; System: ... two lungs are located near the backbone on either side of the heart.
The alveoli are tiny air sacs in the lungs where gas exchange takes place. The mean number of alveoli in a human lung is 480 million. [11] When the diaphragm contracts, a negative pressure is generated in the thorax and air rushes in to fill the cavity. When that happens, these sacs fill with air, making the lung expand.
The end-exhalatory lung volume is now well below the resting mid-position and contains far less air than the resting "functional residual capacity". However, in a normal mammal, the lungs cannot be emptied completely. In an adult human, there is always still at least 1 liter of residual air left in the lungs after maximum exhalation. [6]
The carina of the trachea is located at the level of the sternal angle and the fifth thoracic vertebra (at rest). The right main bronchus is wider, shorter, and more vertical than the left main bronchus, [3] its mean length is 1.09 cm. [4] It enters the root of the right lung at approximately the fifth thoracic
A typical pair of human lungs contains about 480 million alveoli, [11] providing a total surface area for gas exchange of between 70 and 80 square metres. [10] Each alveolus is wrapped in a fine mesh of capillaries covering about 70% of its area. [ 12 ]
An X-ray of a human chest area, with some structures labeled. The contents of the thorax include the heart and lungs (and the thymus gland); the major and minor pectoral muscles, trapezius muscles, and neck muscle; and internal structures such as the diaphragm, the esophagus, the trachea, and a part of the sternum known as the xiphoid process.
The human rib cage is a component of the human respiratory system. It encloses the thoracic cavity, which contains the lungs. An inhalation is accomplished when the muscular diaphragm, at the floor of the thoracic cavity, contracts and flattens, while the contraction of intercostal muscles lift the rib cage up and out.
The mediastinum comprises those organs which lie in the centre of the chest between the lungs. The cavity also contains two openings one at the top, the superior thoracic aperture also called the thoracic inlet , and a lower inferior thoracic aperture which is much larger than the inlet.