The respiratory system is a key part of our survival. It gives the cells oxygen and takes away the carbon dioxide waste. However, if it wasn't for the muscular system, the respiratory system would not be able to help the cells. The way we get the oxygen into our body and the carbon dioxide out is by inhaling and exhaling. This task is made by the contractions of our diaphragm, a skeletal muscle tissue, which change the air pressure making the air inhale and exhale. Also, the muscular system protects us from choking. When we eat and swallow, a flap of smooth muscle called the epiglottis closes over our larynx and trachea to prevent the food from clogging our air ways and stopping breathing. The muscular system is all the part of the reason why we can breathe and give our cells oxygen and survive through our daily lives.
For more info- http://oac.med.jhmi.edu/res_phys/Encyclopedia/Diaphragm/Diaphragm.HTML