Lungs

 Lungs 

    The lungs are a pair of spongy, air-filled organs located on either side of the chest (thorax). 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 eventually end in clusters of microscopic air sacs called alveoli. In the alveoli, 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. Between the alveoli is a thin layer of cells called the interstitial, which contains blood vessels and cells that help support the alveoli.

    The lungs are covered by a thin tissue layer called the pleura. The same kind of thin tissue lines the inside of the chest cavity -- also called pleura. A thin layer of fluid acts as a lubricant allowing the lungs to slip smoothly as they expand and contract with each breath.

Lungs functions 

• The lungs exchange oxygen and carbon dioxide between the air we breathe and the blood.
• The tracheobronchial tree is the passage way from the mouth to the interior of the lung.
• Gas exchange occurs in the alveoli deep in the lungs.
• Breathing air in (inhalation) requires muscular effort.
• Air is warmed, humidified, and cleaned by the nose and lungs.