Final answer:
Several causes can lead to a decrease in the quantity of circulating red blood cells, including faulty hematopoiesis, anemia, and polycythemia.
Step-by-step explanation:
Causes of Decreased Quantity of Circulating Red Blood Cells
There are several causes for a decrease in the quantity of circulating red blood cells:
Faulty hematopoiesis: Disease processes can interfere with the production and formation of RBCs. For example, myeloid stem cells can be defective or replaced by cancer cells, resulting in insufficient quantities of RBCs.
Anemia: Ineffective hematopoiesis can lead to various forms of anemia, where there are insufficient numbers of RBCs. This can be caused by genetic disorders like sickle cell anemia and thalassemia, as well as deficiencies in iron or vitamins needed for RBC production.
Polycythemia: On the other hand, an overproduction of RBCs can lead to a condition called polycythemia. While it does not directly decrease the quantity of circulating RBCs, it increases blood viscosity, making it harder for the heart to circulate the blood efficiently.