The lungs

The lungs are the parts of our body that we use to breathe. They supply oxygen to the organs and tissues of the body. The lungs are divided into areas called lobes. The right lung has three lobes and the left lung has two.

The lungs are covered by a lining called the pleura which has two layers. The inner layer covers the lungs. The outer layer lines the ribcage and a sheet of muscle called the diaphragm that separates the chest from the upper tummy (abdomen).

Structure of the lungs and pleura
Structure of the lungs and pleura

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The lungs are part of our respiratory (breathing) system, which includes the:

  • nose and mouth
  • windpipe (trachea)
  • tubes that go to each lung (bronchus)
  • lungs.

When we breathe in, air passes from our nose or mouth through to the windpipe (trachea). The trachea divides into two tubes (airways) that go to each lung. These tubes are called the right and left bronchus.

Air passes through each bronchus and into the lungs through smaller tubes called bronchioles. At the end of the bronchioles, there are tiny air sacs called alveoli. This is where oxygen from the air we’ve breathed in (inhaled) passes into the blood and is circulated around the body.

A waste gas called carbon dioxide passes from the blood into the air sacs (alveoli). We get rid of carbon dioxide when we breathe out (exhale).

Back to Understanding small cell lung cancer

Types of lung cancer

The main types of primary lung cancer are small cell lung cancer and non-small cell lung cancer. They are treated differently.

What is cancer?

Cancer is a disease of our cells. Sometimes cells go wrong and become abnormal. These cancer cells keep dividing to make more and more abnormal cells.Cancer is a disease of our cells. Sometimes cells go wrong and become abnormal. These cancer cells keep dividing to make more and more abnormal cells.

Why do cancers come back?

Sometimes, cancer cells are left behind after cancer treatment. Over time, these cells can form a new tumour and the cancer comes back.