Atelectasis is composed of 78% nitrogen and 21% oxygen. Since oxygen is exchanged at the alveoli-capillary membrane, nitrogen is a major component for the alveoli's state of inflation. If a large volume of nitrogen in the lungs is replaced with oxygen, the oxygen may subsequently be absorbed into the blood, reducing the volume of the alveoli, resulting in a form of alveolar collapse known as absorption atelectasis. It is usually associated with accumulation of blood, fluid, or air within the pleural cavity, which mechanically collapses the lung. This is a frequent occurrence with pleural effusion, caused by congestive heart failure (CHF).
Regeneration in humans could be grown and expanded outside of the body, with the exception of the liver, nerve and pancreas, as these tissue types need stem cell populations. The first organ ever induced and made in the lab was the bladder, which was created in 1999. In 2014, organs that have been various tissues regenerated by the printer; these tissues include the bladder, muscle, vagina, penis and the thymus. In 2015 researchers developed a proof of principle biolimb inside a laboratory; they also estimated that it would be at least a decade for any testing of limbs in humans. The limb demonstrated,