Download PP-Alveolar gas exchange Notes

Alveolar Gas Exchange
Where does gas
exchange take
place?
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Why is gas
exchange required?
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Why does gas
exchange occur?
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Alveoli in the lungs
Across the respiratory membrane-the wall of a capillary and the
wall of the alveolus
Oxygen in the alveoli travels into blood capillaries in the lungs
Carbon dioxide in the blood capillaries in the lungs travels into the
alveoli
Role of O2
 Required for cell respiration
 During cell respiration, ATP is formed
 Therefore, oxygen is required to make energy
Role of CO2
 Created during cell respiration
 Waste molecule-need to rid the body of the gas
Diffusion:
Alveoli have a high concentration of oxygen
Blood capillaries have a low concentration of oxygen
Blood capillaries have a high concentration of carbon dioxide
Alveolus have a low concentration of carbon dioxide
As a result:
 Oxygen will diffuse from alveoli into the blood capillaries from
high concentration to low concentration (diffusion)
 Carbon dioxide will diffuse from the capillaries to the alveoli
from high concentration to low concentration (again diffusion)
Therefore:
 Blood with a high concentration of oxygen leaves the lungs and
travels to all the cells of the body
Expiration allows carbon dioxide (waste molecule) to leave the body