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Human Performance
The alveoli have a very large total surface area
(around 70 m²), allowing the absorption of large
amounts of oxygen. Top athletes, such as rowers,
can absorb up to 6000 ml of oxygen per minute.
Surrounding the alveoli, in addition to capillaries,
is a network of elastic connective tissue fibers.
The lungs do not contain muscles.
2.3.1.2 Gas exchange in an alveoli
Oxygen-poor blood releases carbon dioxide and
absorbs oxygen. This exchange occurs through diffusion. Carbon dioxide exits
the blood plasma, while oxygen binds to hemoglobin in red blood cells.
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2.3.2 The breathing mechanism
The lungs are essentially free-floating within the chest cavity and are not in
direct contact with the chest wall.
Surrounding the lungs are two closely positioned membranes with fluid in
between.
These membranes, called pleura, are separated by pleural fluid.
The inner membrane adheres to the lungs, while the outer membrane is
attached to the inner chest wall and diaphragm.
When the outer membrane moves, it creates negative pressure between the
membranes, causing the inner membrane to follow, enabling lung movement.
Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 135
