Final answer:
Sickle-cell anemia is caused by an abnormal type of hemoglobin called hemoglobin S, which causes red blood cells to become sickle-shaped, leading to blockages in blood vessels and reduced oxygen delivery to tissues.
Step-by-step explanation:
In sickle-cell anemia, the abnormal component that causes erythrocytes, or red blood cells, to change shape is a mutated form of hemoglobin known as hemoglobin S. This abnormal hemoglobin causes the red blood cells to take on a characteristic sickle or crescent shape. The sickle-shaped cells can become lodged in narrow blood vessels, leading to serious complications such as pain, tissue damage, and organ dysfunction because they are less flexible and can block blood flow to different tissues of the body.
A normal erythrocyte is disc-shaped with a biconcave center, allowing it to bend and flow easily through capillaries. However, sickle cells are elongated and pointed, and they are prone to getting stuck in smaller vessels. Because of the rigidity and abnormal shape, these sickle-shaped erythrocytes cannot carry oxygen as efficiently, which contributes to the symptoms of sickle-cell anemia. Sickle-cell anemia is a genetic condition commonly found in individuals of African descent but can occur in others as well.