The left lung is one of the two lungs in the human body, located on the left side of the chest. It is slightly smaller than the right lung to accommodate the heart, which is positioned slightly to the left. The left lung has two lobes, known as the upper and lower lobes, and is responsible for exchanging oxygen and carbon dioxide during the breathing process. Like the right lung, the left lung is made up of spongy tissue that allows it to expand and contract. Air enters the lungs through the trachea and branches into smaller tubes called bronchi, which lead to the alveoli, where gas exchange occurs. Proper functioning of the left lung is essential for overall respiratory health.