Inside the air sacs, oxygen moves across paper-thin walls to tiny blood vessels called capillaries and into your blood.

A protein called haemoglobin in the red blood cells then carries the oxygen around your body. At the same time, carbon dioxide that is dissolved in the blood comes out of the capillaries back into the air sacs, ready to be breathed out.

Blood with fresh oxygen is carried from your lungs to the left side of your heart, which pumps blood around your body through the arteries.

Blood without oxygen returns through the veins, to the right side of your heart. From there it is pumped to your lungs so that you can breathe out the carbon dioxide and breathe in more oxygen.

What else do the lungs do?

The lungs are exposed to the air so they also play an important protective role in your body, linked to your immune system.

Each breath of air doesn’t only carry oxygen, it also carries germs and other foreign bodies such as pollutants. As a result, your lungs are also designed to prevent unwanted materials from getting into your body.

Mucus is produced in the walls of the small airways to help keep your lungs clean and well lubricated. It is moved by tiny hairs called cilia that line your airways. They move back and forth sweeping a thin layer of mucus out of your lungs and into your throat. Unwanted materials stick to the mucus. When it reaches the throat, it’s usually swallowed without you realising.

If your mucus builds up or if you have an inflammation, coughing can help to clear it from the airways.

So the delicate structure of your lungs is beautifully adapted to breathe and, at the same time, helps protect your body from harm.

But your lungs can be damaged if you breathe in cigarette smoke, polluted air or dusts and fumes in your workplace over a sustained period of time. If your airways get damaged, you can get breathless. Often it’s hard to protect yourself from environmental risks such as air pollution. But you can help protect your lungs by quitting smoking, improving the air quality in your home and doing what you can to reduce your exposure to air pollution.

If you have a lung condition there is plenty of support and advice for you on how to keep active. Attending a pulmonary rehabilitation  programme is another way to help improve your fitness and improve how you use the oxygen that is delivered to your muscles.

Keywords; breathing, oxygen, health