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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
