Final answer:
Anemia is a disorder in which the blood has an inadequate volume of red blood cells, reducing the amount of oxygen that the blood can carry and causing weakness and fatigue.
Step-by-step explanation:
Anemia is a disorder in which the blood has an inadequate volume of red blood cells. This reduces the amount of oxygen that the blood can carry and may cause weakness and fatigue. These and other signs and symptoms of anemia are shown in the figure below. Anemia has many possible causes, including excessive bleeding, inherited disorders such as sickle cell hemoglobin, or nutritional deficiencies (iron, folate, or B12). Severe anemia may require transfusions of donated blood.