The lungs are the principal organs of respiration. A human body has a pair of lung present inside the rib cage above an arched muscle called the diaphragm. The lungs are covered by two thin membranes called pleura. The lungs are cone-shaped organs with spongy texture. This spongy texture helps in the incorporation of inhaled oxygen into the blood. The lungs fill up with air. Hence, the main function of the lungs is the interchange of the gases, oxygen and carbon dioxide.