Complex sentence: Respiration can be described as the mechanical process of air flowing into and out of the lungs on the principle of Boyle's law, stating that, as the volume of a container increases, the air pressure will decrease.
Split into simpler sentences: Respiration can be described as the mechanical process of air flowing into and out of the lungs on the principle of Boyle's Law. As the volume of a container increases, the air pressure will decrease.