The bone marrow produces stem cells, this is what makes your bodys blood cells – red cells, white cells and platelets. The erythropoietin sends a message to the stem cells telling more of them to develop into red blood cells, rather than white cells or platelets.
Blood is made up of blood cells and plasma. Plasma (say: PLAZ-muh) is a yellowish fluid that has nutrients, proteins, hormones, and waste products. The different types of blood cells have different jobs
