The lungs

The lungs are the parts of the body that we use to breathe. We have two lungs (right and left). 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 lobes.

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. The diaphragm separates the chest from the upper tummy (abdomen).

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

View a large version

Read a description of this image

The lungs are part of our respiratory (breathing) system. This system includes the:

  • nose and mouth
  • windpipe (trachea)
  • two tubes (bronchi) that branch from the windpipe going into each lung
  • lungs.

The respiratory system
The respiratory system

View a large version

Read a description of this image

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 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 have breathed in (inhaled) passes into the blood. Then oxygen is circulated through the blood 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).

The lymphatic system

The lymphatic system helps protect us from infection and disease. It also drains lymph fluid from the tissues of the body then returns it to the blood. The lymphatic system is made up of fine tubes called lymphatic vessels that connect to groups of lymph nodes throughout the body. Lymph nodes (sometimes called lymph glands) are small and bean-shaped. They filter bacteria (germs) and disease from the lymph fluid. When you have an infection, lymph nodes often swell as they fight the infection.

Sometimes, cancer can spread through the lymphatic system. If the cancer cells spread outside the lungs, they are most likely to go to lymph nodes nearby in the chest.

Lymph nodes close to the lungs
Lymph nodes close to the lungs

View a large version

Read a description of this image

Back to Understanding

About lung cancer

Lung cancer is a common cancer that is usually caused by smoking.

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.

Why do cancers come back?

Sometimes, tiny cancer cells are left behind after cancer treatment. These can divide to form a new tumour.