To supply the blood with oxygen so that it can transport this oxygen around the body. It does this by: Ventilating the lungs & Transferring oxygen from the air to the blood. It also removes the waste products such as Carbon Dioxide
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The mechanics of breathing
Breathing occurs due to changes in air pressure within the lungs. The respiratory muscles change the area of the lungs. Gases (oxygen and carbon dioxide) move from high pressure to low pressure.
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Inspiration
During inspiration (breathing in) a greater volume in the lungs causes a decreased air pressure in the lungs compared to atmospheric air pressure causes air to rush in. Increase in the size of the lungs, pressure drops and air rushes into the lungs.
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Expiration
During expiration (breathing out) the volume in the lungs decreases causing increased air pressure in the lungs compared to atmospheric pressure leading to air being forced out. Decrease in size of lungs, pressure rises and air rushes out of lungs.
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The respiratory muscles
Internal Intercostal muscles – 11 pairs found between the ribs close to the lungs. External Intercostal muscles – 11 pairs found on top of the Intercostal muscles. The Diaphragm – dome-shaped muscle found at the base of the lungs.
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Ventilation At Rest: Inspiration
External Intercostals contract. Internal Intercostals relax. Lungs increase in width. Diaphragm contracts and flattens.
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Ventilation At Rest: Expiration
External Intercostals relax. Internal Intercostals contract (don’t need to at rest). Lungs return to normal size. Diaphragm relaxes and returns to normal size.
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Ventilation During Exercise: Inspiration
More oxygen required. External intercostal muscle contract harder. Sternocleidomastoid and scalene muscles also used to raise ribs and sternum. Trapezius and neck extensors used. Diaphragm contracts harder. Increase volume of the thorax.
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Ventilation During Exercise: Expiration
Internal intercostals muscles contract. Abdominal muscles contract to help push air out of the lungs.
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Other cards in this set
Card 2
Front
The function of the respiratory system
Back
To supply the blood with oxygen so that it can transport this oxygen around the body. It does this by: Ventilating the lungs & Transferring oxygen from the air to the blood. It also removes the waste products such as Carbon Dioxide
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