As we breathe in and out the lungs inflate and deflate with air, taking oxygen into the body and removing carbon dioxide from the body.
When we breathe in, air passes from our nose or mouth through the windpipe (trachea), which divides into two tubes (airways), one going to each lung. These are known as the right and left bronchus.
They divide to form smaller tubes called bronchioles, which carry air through the lungs. At the end of the bronchioles are millions of tiny air sacs called alveoli. In the alveoli, oxygen is absorbed from the air we breathe in and passes into the bloodstream to be circulated around the body.
Carbon dioxide is a waste gas that needs to be removed from the body. It passes from the bloodstream into the alveoli and is then breathed out from the lungs.
The right lung has three main areas (known as lobes) and the left lung has two. Many lung cancers start in the cells lining the bronchi and are called carcinomas of the bronchus.
The lungs are covered by a membrane, or lining, called the pleura, which has an inner and outer layer.
The inner layer covers the lungs. The outer layer lines the ribcage and the diaphragm - a sheet of muscle that separates the chest from the abdomen.
The pleura produces a fluid that acts as a lubricant, which helps you to breathe easily and allows the lungs to move in and out smoothly.
The lymphatic system
The lymphatic system is part of the immune system - the body’s natural defence against infection and disease. It’s made up of organs such as bone marrow, the thymus, the spleen, and lymph nodes.
The lymph nodes throughout the body are connected by a network of tiny lymphatic tubes (ducts).
The lymphatic system has two main roles: it helps to protect the body from infection and it drains fluid from the tissues.