The lymphatic system helps protect us from infection and disease. It also drains lymph fluid from the tissues of the body, before returning it to the blood.
The lymphatic system is made up of fine tubes called lymphatic vessels. They 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.