Lungs and linked blood vessels deliver oxygen to the body and remove carbon dioxide. The lungs lie on either side of the breastbone and fill the inside of the chest cavity. The left lung is slightly smaller than the right lung to allow room for the heart.
Within the lungs, the bronchi branch into thousands of smaller, thinner tubes called bronchioles. These tubes end in bunches of tiny round air sacs called alveoli.
Each of these air sacs is covered in a mesh of tiny blood vessels called capillaries. The capillaries connect to a network of arteries and veins that move blood through your body. The pulmonary artery and its branches deliver blood rich in carbon dioxide (and lacking in oxygen) to the capillaries that surround the air sacs. Inside the air sacs, carbon dioxide moves from the blood into the air. Oxygen moves from the air into the blood in the lungs.
The oxygen-rich blood then travels to the heart through the pulmonary vein and its branches. The heart pumps the oxygen-rich blood out to the body. The lungs are divided into five main sections called lobes. Some people need to have a diseased lung lobe removed. However, they can still breathe well using the rest of their lung lobes.
Muscles Used for Breathing
Muscles near the lungs help expand and contract (tighten) the lungs to allow breathing. These muscles include the:
- Diaphragm
- Intercostal muscles
- Abdominal muscles
- Muscles in the neck and collarbone area
The diaphragm is a dome-shaped muscle located below your lungs. It separates the chest cavity from the abdominal cavity. The diaphragm is the main muscle used for breathing.
The intercostal muscles are located between your ribs. They also play a major role in helping you breathe.
Beneath the diaphragm are abdominal muscles. These help you breathe out when you're breathing fast (for example, during physical activity). Muscles in the neck and collarbone area help you breathe in when other muscles involved in breathing don't work properly, or when lung disease impairs your breathing.
The National Heart, Lung, and Blood Institute (NHLBI) is a research, training, and education program to promote the prevention and treatment of heart, lung, and blood diseases.