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What causes oxygen to diffuse from the lungs into the capillaries? A. Equal oxygen...

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pradipshah90 | Student, Undergraduate | eNotes Newbie

Posted December 14, 2009 at 11:57 PM via web

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What causes oxygen to diffuse from the lungs into the capillaries?

A. Equal oxygen concentration in lungs and capillaries

B. Oxygen concentration is lower in lungs

C. Oxygen concentration is lower in capillaries

D. Blood from pulmonary arteries is high in oxygen

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enotechris | College Teacher | (Level 2) Senior Educator

Posted December 15, 2009 at 4:28 AM (Answer #1)

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The answer is C, the oxygen concentration is lower in the capillaries relative to the lungs.  Likewise, at the alveoli, where this transaction occurs, the concentration of carbon dioxide is higher in the capillaries and lower in the lungs, so that migrates into the lungs to be breathed out.  The oxygenated blood then gets pumped throughout the body where it gives up its oxygen to the cells.  The deoxygenated blood then returns to the lungs to become oxygenated once again.

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versatilekamini | College Teacher | Valedictorian

Posted December 15, 2009 at 8:48 PM (Answer #2)

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Respiration is a mechnical process and is completed in two phases, inspiration and expiration. In inspiration, the ribs are elevated and the diaphragm contracted and flattened, the chest cavity is enlarged. This increase in the volume of the chest cavity and lungs causes the air pressure in the lungs to fall below the atmospheric pressure, and air passes through the air passageways to the lungs to equalize the pressure. In expiration, the ribs and diaphragm return to their original position, the chest cavity volume is decreased. The distended elastic lungs then contract and the air is forced out.

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