A 7-year-old African American boy complains of fever, swelling of hands and feet and yellow sclera. He is diagnosed with sickle cell disease. The extent of tissue damage found in children with sickle disease results from which of the following?
•In sickle cell anemia, RBCs become characteristically elongated and crescent-shaped (sickled) when they are exposed to low oxygen tension, a low blood pH, or increased blood viscosity such as occurs with dehydration or hypoxia.
•When RBCs sickle, they do not move freely through vessels. Stasis and further sickling cause blockage and ischemia resulting in acute pain and cell destruction.
•The actual anemia is caused by hemolysis, not deoxygenated blood cells.
•Sickle cell anemia is not related to bilirubin levels.
•Sickle cell anemia is not an autoimmune disease.
•Tissue damage is not a result of elevated bilirubin.