Final answer:
Red blood cells live for about 120 days, after which they are recycled in the liver and spleen by phagocytic macrophages. They are made in the red bone marrow and are essential for oxygen transport due to their hemoglobin content. In sickle cell anemia, their lifespan is reduced due to the instability of HbS.
Step-by-step explanation:
Typically, red blood cells, or erythrocytes, have a lifespan of approximately 120 days in the bloodstream. Once they reach the end of their life cycle, they are broken down and recycled by phagocytic macrophages, a type of white blood cell. This process takes place primarily in the liver and spleen.
It is important to note that mature erythrocytes lack a nucleus and other organelles, which allows for an increased capacity to carry hemoglobin and thus transport more oxygen. These cells are made in the red bone marrow and then released as reticulocytes, which mature into erythrocytes in the bloodstream.
In certain medical conditions, such as sickle cell anemia, the lifespan of red blood cells is significantly reduced, often to about 30 days due to instability and excessive hemolysis of HbS (hemoglobin S), leading to anemia with symptoms that may include physical exertion, weakness, shortness of breath, leukemia, and heart murmurs.