Define breathing mechanism in Human beings?

In breathing, human beings inhale oxygen and exhale carbon dioxide.During inhalation process, the diaphragm contracts and moves down. The ribcage moves upwards and outwards and expands. This results in increasing the volume of the chest cavity and reduces the pressure inside it as volume is inversely proportional to pressure. When the pressure inside the lungs reduces then During exhalation process, the diaphragm relaxes as it moves up and returns to its normal dome shape. The ribcage also returns to its normal position. This reduces the volume of the chest cavity, which in turn increases the pressure inside it. And thus air is expelled out. In this way, process of breathing takes place in human beings.