We breathe in and out, or inhale and exhale to ventilate our lungs.

... We breathe in and out, or inhale and exhale to ventilate our lungs. This allows an important exchange of gases to take place. * Oxygen in the alveoli goes into our blood and carbon dioxide goes out of our blood into the alveoli. 2. Gaseous exchange Gaseous exchange means getting oxygen from the air into our blood and getting carbon dioxide out of our blood into the air. Gaseous exchange happens by diffusion of gases across the very thin walls of the alveoli. The lungs must have a very large surface area to make this efficient. Breathing... * Is necessary to absorb oxygen into our blood. * Is necessary to remove carbon dioxide from our blood. * Is faster when you take exercise. * Is slower when you are lying down at rest. Wise-up words Epiglottis This is a little flap on the back of the tongue; it closes the top of the trachea when we swallow so that food

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