The lungs are a pair of spongy, air-filled organs located on either side of the chest .Air enters the body through the nose or mouth. The trachea (windpipe) conducts inhaled air into the lungs through its tubular branches called bronchi. The bronchi then divide into smaller and smaller branches (bronchioles), finally becoming microscopic.
The bronchioles end in microscopic air sacs called alveoli in which oxygen from the air is absorbed into the blood. Carbon dioxide, a waste product of metabolism, travels from the blood to the alveoli, where it can be exhaled.
The right lung has three parts (lobes) while the left lung has two lobes.