Sickle cell anemia is a form of anemia, a condition in which there is a lower than normal number of red blood cells in the blood. Red blood cells normally live for three to four months. People with sickle cell anemia have abnormal cells known as sickle cells, which are fragile and begin to break down after 10 to 20 days. This often results in a shortage of red blood cells because it is difficult for the body to produce enough replacements.
Red blood cells are produced in the bone marrow, the soft inner component of bones. They contain hemoglobin, an iron–rich proteinmolecule that picks up oxygen from the lungs and releases it to the tissues as blood travels through the body. In healthy individuals, the body produces normal hemoglobin (hemoglobin A). In people with sickle cell anemia, red blood cells mostly contain an abnormal form of hemoglobin know as hemoglobin S. Hemoglobin S reduces the amount of oxygen in the cells. As a result, the shape of the cells becomes distorted.
Red blood cells are normally disc–shaped, flexible and smooth. This allows them to travel easily through the blood vessels of the body. In people with sickle cell anemia, however, red blood cells undergo a structural change and become crescent shaped under reduced oxygen conditions. The cells are named after the sickle, a crescent–shaped tool used to cut wheat. Red blood cells containing hemoglobin S can change from normal shape to sickle shape and back again until they become permanently sickle–shaped.
