Question

The 120 days is the lifespan of
A. Red blood cells
B. White blood cells
C. Platelets
D. Red blood cells and Platelets

Answer 1

Hint: RBCs or erythrocytes are produced in red bone marrow by a process known as erythropoiesis. Once they have completed their lifetime phagocytosis occurs with the help of macrophages that are specialized structures such as lymph nodes, spleen and liver.

Step by step answer:The life cycle of RBCs is completed in 120 days. The process by which they are digested by macrophages is known as erythropoiesis. The process of digestion is known as phagocytosis. The process is a form of apoptosis, which is the process of programmed cell death. Helps in making the amount of circulating RBCs in the blood at a constant rate.
White Blood Cells or WBCs also known as leukocytes function as protective cells for the body. These cells have a lifespan of 13 to 20 days and are destroyed in the lymphatic system. Actual amounts of leukocytes are important for the right functioning of the immune system. Increased WBC count may result in autoimmune disorders such as rheumatoid arthritis.
Platelets have a very short lifespan compared to other blood cells. The survival time of platelets is only 10 days and then they have to be removed from the circulation. Thus, there is a balance between the production and removal of these cells. These cells act in the process of blood clotting.
Thus, the right option is A. Red blood cells

Note: The process of erythropoiesis is initiated or stimulated by a hormone known as erythropoietin, produced from the kidneys. This hormone is abundantly produced during hypoxia, in which oxygen level is low.