PE Mechanics of Breathing

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Created by: John Deere 6R
Created on: 29-01-18 12:37

Breathing

Breathing is a two way process.

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Inspiration

Is the intake of air into the lungs which is brought about by increasing the volume of the chest cavity.

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Expiration

Is the expulsion of air from the lungs through reducing the volume of the chest cavity.

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Use of muscles

Both these types of breathing involve the use of muscles, the diaphragm and intercostal muscles. When these muscles contract they cause the chest cavity to increase in size and therefore increase its volume.

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During inspiration

Breathing muscles contract. Contraction of the dome shaped diaphragm causes it to flatten. This enlarges the chest cavity. At the same time, contraction of the intercostal muscles causes the ribs to rise, this increases the size of the chest cavity.

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During inspiration (chest cavity expanding)

The volume increases. This reduces the pressure in the chest cavity and the air is drawn into the lungs. Air passes from the higher pressure outside the lungs to the lower pressure inside the lungs.

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During expiration

Breathing muscles relax. The diaphragm curves and returns to its dome shape; the weights of the ribs causes them to descend and the chest volume decreases.

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