Respiration is the sequence of events that results in the exchange of oxygen and carbon dioxide between the atmosphere and the body cells. Air moves through a series of passages into and out of the lungs. After this, there is an exchange of gases between the lungs and the blood in small sacs in the lungs called alveoli. This is called external respiration. The blood transports the gases to and from the tissue cells. The exchange of gases between the blood and tissue cells is internal respiration. Finally, the cells utilize the oxygen for their specific activities: this is called cellular metabolism, or cellular respiration. Together, these activities constitute respiration!!!

*Respiratory system is the network of organs by which we could respirate(breath).The organs of the respiratory system extend from the nose to lungs. They include the nose, pharynx, trachea, bronchi, and bronchioles.