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The Alveoli. They are very numerous. The average adult lung contains millions of alveoli. This provides a great surface area for the diffusion of gases. Alveolar walls are only one cell thick which aids the diffusion of gases.
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They are very numerous. The average adult lung contains millions of alveoli. This provides a great surface area for the diffusion of gases. Alveolar walls are only one cell thick which aids the diffusion of gases. Alveoli are the location of external respiration and are specialized for their function in a number of ways:
The alveoli have a coating of lipoproteins on their inner surface, which helps maintain surface tension. This prevents them from collapsing and sticking together during exhalation Alveoli are the location of external respiration and are specialized for their function in a number of ways:
They are supplied with stretch receptors. These nerve endings are sensitive to stretch. The alveoli expand during inhalation. The stretch receptors send impulses to the medulla oblongata of the brain when the alveoli are full enough (stretched).This triggers exhalation. Alveoli are the location of external respiration and are specialized for their function in a number of ways:
The alveoli are kept moist. If they dried out, efficient diffusion of gases would be impossible. The alveolar surfaces are highly vascularized by the pulmonary capillaries. This ensures maximum diffusion of gases. Alveoli are the location of external respiration and are specialized for their function in a number of ways: