Heart and lungs

Have a look inside the lungs! What happens when the oxygen you inhale is absorbed by the blood, and what does it feel to touch a lung?

The organ in the model is three quarters of normal size. In the model you can see the windpipe (trachea) and bronchial tubes, which provide the lungs with air when breathing. The bronchial tubes pass into the bronchioles inside the lungs. The bronchioles look like the branches of a tree in the lungs.

The left lung consists of two lobes  to make space for the heart in the chest. The right lung consists of three lobes. The lungs are made up of a special kind of tissue with lots of lung cavities that contain air, also known as alveoli. If you touch a lung, it feels sort of like a sponge. The walls of the lung cavity are thin to allow oxygen and carbon dioxide to pass through them easily. The lung cavities are surrounded by a network of small blood vessels called the capillary network.

In the lungs, the exchange of gas occurs between the respiratory air and the blood. Oxygen in the inhaled air is absorbed by the blood, and carbon dioxide in the blood is released to the exhaled air. The blood in the capillaries around the lung cavities contains carbon dioxide from the body's tissues, which is transported to the lungs by the pulmonary arteries. This carbon dioxide can either be loose in the blood or bound to haemoglobin, the pigment in the blood. The carbon dioxide passes between the walls of the capillaries and the lung cavities to the lungs. When you exhale, the carbon dioxide leaves the body.

In the lung cavities, oxygen is absorbed from the inhaled air. The oxygen is transported in the opposite direction from the lung cavities to the capillaries, and then continues through the pulmonary veins to the heart and into the body. The oxygen transported in the blood is mainly bound to haemoglobin.

The organs in the model are three-quarters the size of real organs. Here, you can learn more about the heart.