Your heart and blood vessels are the little highways that move blood through your body. Together they are called your vascular system.
A poisonous liquid that some bugs inject when they bite or sting you. It can make you itch or even make you sick.
A type of germ that can cause an infection, such as a wart.
Vitamins are found in food, and you need them to keep your body healthy. There are many kinds of vitamins. For instance, you need vitamin A for your eyes, and you can get it in carrots and egg yolks. Vitamins also can be put in pills, and some people take them to be sure they get everything they need.