Gas Exchange at the Alveoli |
In the lungs, gas exchange happens in the alveoli. Oxygen diffuses out of the alveoli and into the capillaries. Because of the pressure gradient, oxygen diffuses down and moves out of the alveoli and enters the blood of the capillaries. Oxygen binds to hemoglobin, which is found in red blood cells. Red blood cells then carry the oxygen to tissues where the oxygen dissociates and diffuses into the cells in the tissues. Overall, gas is exchanged by diffusion.
What Causes the O2/CO2 Exchange?
When the pressure of the O2 is lower in the alveoli than the external environment, oxygen diffuses into the alveoli.
When the pressure of CO2 is higher in the capillaries than in the alveoli, there is diffusion into the alveoli. Then, it is exhaled during expiration.
What Causes the O2/CO2 Exchange?
When the pressure of the O2 is lower in the alveoli than the external environment, oxygen diffuses into the alveoli.
When the pressure of CO2 is higher in the capillaries than in the alveoli, there is diffusion into the alveoli. Then, it is exhaled during expiration.
How Air Moves Into and Out Of Lungs
When your diaphragm contracts, it pushes up the abdominal cavity. Air is then sucked in through the mouth or nose because of the vacuum that is created. This is inhalation. During exhalation, the lung contracts, which forces air out of the lungs and back out through the mouth and nose. While this is happening, gas exchange is occurring in the alveoli and capillaries.