Blood is the fluid connective tissue and it plays a very vital role in the human body. There are 4 primary components of blood and they are Red Blood Cells and White Blood Cells, platelets and plasma. Plasma makes up around 55 % of the human blood in the body.
The blood performs three major functions in the human body, namely:
- Regulation of body temperature and also regulates the pH level of the body.
Red Blood Cells
The Red blood cells are also called erythrocytes. RBCs store the haemoglobin, which is a respiratory pigment that binds to oxygen or carbon dioxide molecules. This helps in the transportation of the oxygen to different tissues and organs of the human body. It also takes away the carbon-dioxide from these organs and tissues to be replenished in the lungs.
Haemoglobin mainly comprises of iron which combines with the oxygen, thus giving the reddish colour to the blood. It occupies 40-45% of the total volume of blood. The main function of the RBCs is the transportation of nutrients and the hormones throughout the human body.
Lifespan of RBC
The lifespan of RBC is 100-120 days. When their lifespan is completed, they are removed from the circulation. When a person suffers from chronic diseases, the lifespan of RBCs is reduced.
Also Read: Body Fluids and Circulation
White Blood cells
The white blood cells are also called Leukocytes. These act as defence agents against any infections in the human body. They produce a special kind of protein called an antibody which recognizes and fights against the foreign entities invading the human body. These cells are classified further as granulocytes and agranulocytes.
Granulocytes have visible granule-like structures in the cell bodies, hence their names. On the other hand, agranulocytes do not possess these granule-like structures. The three kinds of granulocytes are neutrophils, basophils, and eosinophils.
WBCs comprise 1% of the total volume. They are colourless because they are devoid of haemoglobin.
Lifespan of WBC
The lifespan of WBC is 12-20 days. After that, they are destroyed in the lymphatic system. The immature WBCs released from the bone marrow into the peripheral blood and are called bands or stabs.
Let us learn more about the difference between the red blood cells and white blood cells.
Difference between Red Blood Cells and White Blood Cells
|RBC – Red Blood Cells||WBC – White Blood Cells|
|Red blood cells are called as Erythrocytes.||White Blood Cells are called as Leucocytes or Leukocytes.|
|RBCs are shaped as bi-concave discs.||These have an irregular shape.|
|Size varies from 6 – 8 µm in diameter.||Size varies from 12 – 17 µm in diameter.|
|These cells have a lifespan of about 120 days.||These have a lifespan of around 13-20 days after which, they are destroyed in the lymphatic system|
|Red blood cells do not have a nucleus at maturity.||WBCs are characterized by the presence of a large central nucleus.|
|Due to the presence of haemoglobin, these cells appear red in colour.||These cells are colourless, as they do not have any pigment.|
|Only one type of RBCs exists.||Different types of WBC’s are found in the blood such as neutrophils, B lymphocytes, T lymphocytes, monocytes, basophils, eosinophils.|
|They help in the transport of respiratory gases to different parts of the human body||They help in producing antibodies to fight against diseases causing microbes.|
|RBCs are produced in the red bone marrow||These cells are produced in the red bone marrow, lymph nodes, and spleen, etc.|
|The components of red blood cells are haemoglobin.||The components of white blood cells are antibodies with the presence of MHC (major histocompatibility complex) antigen cell markers.|
|These cells make up around 36-50% of human blood.||They make up around 1% of the human blood.|
|They are about 5 million/ mm³ of blood.||They are about 7000–8000/mm³ of blood.|
|The process of formation of RBC is known as erythropoiesis.||The process of formation of WBC is known as leukopoiesis.|
|These cells move between the cardiovascular systems.||These cells move between the cardiovascular and lymphatic systems.|
|Low count of RBCs results in Anaemia.||Low count of WBC’S results in Leukopenia.|
Also Read: Blood
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