Red Blood Cells vs. White Blood Cells
What are Red Blood Cells?
Also known as erythrocytes, is the most common and important component of blood for delivering oxygen to the whole body tissues. RBCs present in the blood travels throughout the body via circulatory system. Along with oxygen they also have a ability to bind with CO2 as well. RBCs take O2 from our respiratory tract which then binds to the hemoglobin. Hemoglobin contains 4 subunits of an iron containing molecule called heme. Heme a subunit of hemoglobin have a capability of binding O2, one heme can bind one oxygen only. Therefore single hemoglobin can carry up to 4 O2 molecules. And the red color of RBCs is because of heme group. Cell wall of RBCs are made up of lipids and proteins and they are biconcave in shape which allow them to move even from the narrowest vessels by providing stability, flexibility and deformability. In mammals, RBCs contain nuclei in their early stages as they mature they become anucleate and lose some of their organelles. RBCs are formed in bone marrow in adults while in embryo they are derived from yolk sac which later in embryonic life is formed by liver. They cannot multiply on their own so, the old cells can only be replace by the new cell formed in the bone marrow which leads them to shorter life span of 120 days.
What are White Blood Cells?
White blood cells or leukocytes are involved in providing immunity. WBCs protect us from infectious and foreign organisms. WBCs are present in blood and lymphatic fluid. They do not contain heme, so they are colorless. The WBCs count in blood varies with type of disease. WBCs only comprises 1% of total blood as compared to RBCs which is 40-50% still this 1% is important for maintaining normal body immune system. If WBCs level becomes below 1% then our body is vulnerable to different infection as in case of HIV where WBCs counts drops to critical level. WBCs are of two different types granulocytes and agranulocytes. Granulocytes further divides into following types: neutrophils, basophils, eosinophils, mast cells. Agranulocytes are of two types named monocytes and lymphocytes. All the WBCs contain nucleus, they have shape according to their function. They are produced in bone marrow but they have ability to multiply to destroy foreign invader. Their life span varies between hours and days except lymphocytes which can survive up to weeks or years.