Overview of the Lungs
The lungs are the organs involved in breathing.
All the cells in your body need oxygen to turn food into energy. The process of turning food into energy creates waste in the form of carbon dioxide, which must be released from your body.
You have 2 lungs in your chest, surrounded by your rib cage. Air comes into your lungs through your windpipe, also called the trachea. The windpipe divides into smaller airways called bronchi. Like branches of a tree, bronchi divide into even smaller airways called bronchioles. The bronchioles end in millions of very tiny air sacs called alveoli.
Your airways are lined with very tiny hairs. Your airways also make mucus that coats their lining. Together, the hairs and mucus filter and trap dust and germs so they don't get into your lungs. A little flap called the epiglottis keeps food out of your windpipe when you swallow.
The average adult breathes 15 times each minute while resting. A moderately active person breathes 5,000 gallons (almost 20,000 liters) of air every 24 hours.
Your brain automatically sends messages for you to breathe, even when you're asleep or passed out.
Your brain sends signals to your rib and diaphragm muscles to make you breathe. To inhale, muscles between your ribs contract and your diaphragm contracts. Your diaphragm is a big, flat muscle that separates your chest and belly. Your lungs don't have muscles of their own.
Your lungs contain tiny air sacs called alveoli. Blood flows through the walls of the air sacs and picks up oxygen from the air in the sacs. At the same time, carbon dioxide leaves your blood and goes into the air sacs. The carbon dioxide then can leave your body when you exhale.
All the blood in your body passes through your lungs every minute or so. That means the lungs need lots of large blood vessels.
Gas Exchange Between Alveolar Spaces and Capillaries
Problems that involve your brain, like a stroke, drug overdose, or extreme alcohol intoxication, can interfere with the part of your brain that controls breathing. These problems can make you breathe too slowly or even stop breathing.
The airways can become narrowed by asthma or blocked by a foreign body such as a piece of food.
Blood vessels inside your lungs can be blocked by blood clots, called a pulmonary embolism.