Breathing:Theprocessofrespiration, during which air is inhaled into thelungsthrough themouthornosedue tomusclecontractionand then exhaled due to muscle relaxation.
![](https://images.rxlist.com//images/slideshow/heart-disease-visual-guide-s1-arteriogram-of-healthy-heart.jpg)
Breathing:Theprocessofrespiration, during which air is inhaled into thelungsthrough themouthornosedue tomusclecontractionand then exhaled due to muscle relaxation.