The lungs enable our bodies to receive oxygen through inhalation and remove toxic carbon dioxide from our bodies through exhalation. Each day, an individual will take about 25,000 breaths. The air contains several gases, including oxygen, that is needed for proper cell function. With each breath, lungs add fresh oxygen to the blood, which then carries it to the cells. Oxygen enters the lungs via the trachea, which branches into two main tubes supplying the right and left lung. These tubes progressively branch 22 additional times to form more than 100,000 smaller tubes (bronchi, bronchioles) and more than 300 million alveoli (air sacs).
The lungs also play an important role in the body’s defense against infection and other harmful environmental factors. Mucus, a sticky fluid produced in the lungs, can trap inhaled agents and aid white blood cells in destroying harmful bacteria. The lung has a spongy texture. The lung is relatively light in weight and can float in water. It is also highly elastic, which enables it to expand and contract efficiently. The lungs are located in two cavities, on either side of the heart. Though similar in appearance, they are not identical. The environment of the lung is very moist, which attracts bacteria. Many respiratory illnesses are the result of bacterial or viral infection of the lungs. Inflammation of the lungs is known as pneumonia and inflammation of the pleura surrounding the lungs is known as pleurisy.