Blood is made of blood cells floating in plasma. The plasma is mostly made of water with chemicals in it. These chemicals include proteins, hormones, minerals and vitamins.
There are three basic types of blood cells. These include:
- Red blood cells (RBCs) are also called erythrocytes. They make up almost half of blood. Red blood cells are filled with hemoglobin. That's a protein that picks up oxygen in the lungs and brings it to cells all around the body.
- White blood cells (WBCs) are also called leukocytes. They fight disease and infection by attacking and killing germs that get into the body. There are several kinds of white blood cells, each of which fights a different kind of germ.
- Platelets are also called thrombocytes. They are small pieces of cells that help blood clot and stop bleeding.