The blood circulates throughout your whole body because one of the aims of blood is to provide food, oxygen, hormones and other chemicals to all the body's cells.

Bone Marrow is called as the "blood cell factory" as it fills up the cavities of bones. The fact is that all the blood cells are originated and produced from a single "stem cell" that has progeny  that grow and mature into different types of blood cells. The most important feature of  stem cell is that it can grow and renew itself as per the individual requirement of every body structure.

Red blood cells that are known as erythrocytes and are responsible for carrying oxygen from the lungs to each and every potion of the body. If you don't have enough red blood cells, then it can cause a very serious disorder called anemia.

In this condition, a person normally looks very pale and the condition may make you feel tired, dizzy, irritable and short of breath. RBCs that is Red Blood Cells are also responsible for picking up wastes on their way around the body, and carry them to  lungs so that they can be exhaled out in the form of  carbon dioxide.

White blood cells that are also known as leucocytes or WBC, are called as the body's infection fighters. There is the existence of three types of white blood cells: granulocytes, lymphocytes and monocytes.
Their main motto is to make our body get rid of all the disease-causing bacterias, viruses, fungi. They are also responsible for destroying the body's dead or defective cells.

Platelets, on the other hand, are a form of small cells that help the body in preventing bleeding and makes blood clot, immediately after an injury is caused. When a blood vessel is damaged or cut, platelets immediately run to that particular area and block  together to plug the bleeding site.