Watch this video to learn about how the body makes red blood cells, which contain hemoglobin and carry oxygen throughout the body. Anemia occurs when there are too few red blood cells or not enough hemoglobin. Find out more about anemia and other blood disorders by visiting ASH’s patient resources webpage http://hematology.org/Patients/. This animation was featured in the documentary film “Blood Detectives.” To learn more about the film, visit http://www.hematology.org/Publications/Blood-Detectives/5246.aspx