Immune System
These cells attack invading germs.
What are white blood cells?
These two systems work together to deliver oxygen to body cells.
What are the respiratory and circulatory systems?
These are foreign invaders that make you sick.
What are pathogens?
This fluid in your body helps fight infection and contains white blood cells.
What is lymph?
These structures filter lymph and trap germs.
What are lymph nodes?
This process introduces a weakened germ to help your body build immunity.
What is vaccination?