The respiratory system brings oxygen into the lungs and blood through breathing. Air enters the lungs through the windpipe and branches into smaller tubes called bronchi and bronchioles. The bronchioles end in tiny air sacs called alveoli that are surrounded by capillaries. Oxygen passes from the alveoli into the blood in the capillaries, while carbon dioxide passes from the blood into the alveoli to be exhaled. The diaphragm and ribs help expand and contract the lungs during inhalation and exhalation.

1. THE RESPIRATORY SYSTEM By Danielle Nader

2. This chart of the respiratory system shows the apparatus for breathing. Breathing is the process by which oxygen in the air is brought into the lungs and into close contact with the blood. which absorbs it and carries it to all parts of the body. At the same time the blood gives up waste matter (carbon dioxide), which is carried out of the lungs with the air breathed out.

3. Notes on the Respiratory System When you breathe in, fresh air goes into your lungs. Then the air goes from the lungs into your blood. Stale air, called carbon dioxide, comes out of the lungs. You breathe it out.

4. When you breathe in through your mouth or nose, air travels down your windpipe and into your lungs. The windpipe is called the trachea. At the end of the trachea there are two big tubes : just one is called bronchus and the two together are called bronchi. Each bronchus goes to a lung. The bronchi branch off into smaller tubes and then smaller ones.

5. The tiniest ones are called bronchioles, and they are covered with millions of tiny air sacs called alveoli. These air sacs fill with air and the lungs get bigger.

6. Each air sac is covered with tiny blood vessels called capillaries.

7. Blood which has travelled around the body and has had all the oxygen taken from it, comes into the lungs from the heart through the blood vessels. The blood is carrying carbon dioxide which the body doesn't want.

8. The blood leaves the carbon dioxide in the lungs and picks up fresh oxygen from the lungs. When you breathe out, the carbon dioxide leaves your body. The fresh oxygen is carried around the body in the blood.

9. The lungs are protected by the ribs. Under the ribs there is a muscle called the diaphragm . It works with your lungs as you inhale and exhale.