Dr Mark Rosenthal


Consultant in Paediatric Respiratory Medicine

also specialist in Food Allergies & Disorders of Sleep

A | A | A

T: 0207 351 8832

E: s.harvey@rbht.nhs.uk

A:The Royal Brompton Hospital, London, SW3 6NP

What Do Your Lungs Do?

Knowing a bit about what the lungs look like and what they are busy doing all day can help make sense of what your respiratory paediatrician is telling you.


  1. Breathe: The brain tells your lungs how often you need to breathe, depending on your activity level. It signals the muscles between your ribs to breathe in while your diaphragm is flattened to provide more space for your lungs. Air is drawn in through your nose or mouth, down your throat and windpipe. It splits into the two bronchi that lead to the left and right lungs. Your respiratory paediatrician may mention these tubes as they are what spasm during an asthma attack. The bronchi branch into smaller thousands of smaller bronchioles, which lead to air sacs called alveoli. When your rib muscles and diaphragm relax again, you breathe out.

  3. Exchange Oxygen and Carbon Dioxide: The real work of the lungs goes on inside the alveoli, which have very thin walls covered in fine blood vessels called capillaries. Every cell in your body needs oxygen to survive, but the only way to get it into your body is through the lungs. Oxygen can move quickly from the air you breathe in, across the thin alveolar walls, and into your bloodstream. The blood goes from your lungs straight to your heart, which pumps it all around the body. After the oxygen has been used up, the blood returns to your heart, which pumps it into your lungs. It can then pick up more oxygen while getting rid of the waste product carbon dioxide that it has collected from around your body.

  5. Protect Themselves: In order to keep doing their job well, your lungs also have to protect themselves against the dust, bacteria, pollutants and other material that comes in with the thousands of litres of air that you breathe every day. The airways produce mucus to keep themselves clean and lubricated. If your respiratory paediatrician diagnoses a lung infection, the symptoms are probably caused by increased production of this mucus as your lungs try to clear out the infection. The bronchi also have tiny hair-like structures called cilia, which work together to move mucus, dust and other things out of your lungs.