Tag Archives: haemoglobin


In a human body, there are three major functions of the blood that includes regulation, transportation, and protection. The blood is made up of three types of cells that involve red blood cells, white blood cells, and blood platelets. In here the difference between the red blood cells and the white blood cells are to be identified.

Structure of Red blood cells (RBCs):

The red blood cells (RBCs) are uniquely structured. They are oval and biconvex in shape which is flexible in nature. The oval biconvex disc shape helps the RBCs to have increased surface area in comparison to the volume ratio of the extremely smaller cells enabling carbon dioxide and oxygen to be diffused across the plasma membrane of the red blood cell easily.

The RBCS lacks the nucleus and has no mitochondria or endoplasmic reticulum. This helps them to carry an increased amount of oxygenated blood and haemoglobin as well as helps it to form a disc-shaped structure that helps it ineffective diffusion with ease.

There are enzymes present in the RBCs which allow them to produce a small amount of ATP from the glucose in the form of energy.

The most important structural part of the RBCs is haemoglobin. The Haemoglobin is a molecule which is responsible for carrying oxygen by the RBCs. It helps the RBCs to develop a red colour.

The haemoglobin consists of heme and globin. The formation of heme occurs when the succinyl-CoA effectively binds with glycine in order to form pryrole molecule. The four of the produced pyrrole molecules are combined together to form protoporphyrin IX that helps to bind the iron with the heme molecules. The globin is seen to be a polypeptide chain. During the combination of the heme and globin molecule, a haemoglobin chain is formed. There are slight variations in the chains formed and they are as per designated as alpha, beta, gamma and delta chains.

In order to form the final haemoglobin, four of the chains are required to be combined. The most common form of haemoglobin in a human body is haemoglobin A which is formed by a combination of two alpha and beta chains. Each of the molecules of iron is seen to bind with one of the molecule of oxygen which consists of two atoms of oxygen. In a single haemoglobin chain, there is one iron atom and four haemoglobin chains.

Thus, each of the haemoglobin chains is able to carry a total of eight oxygen atoms. In each 100mm of blood, it consists of 15g of haemoglobin apart from other blood components.

Structure of White Blood cells:

The white blood cells are components of the blood which protects the body from any infectious agents. The WBCs are also known as leucocytes and these are originated from the bone marrow and are circulated through the lymph and blood system. They can be granulocyte or agranulocyte and they migrate from the blood vessels to the tissues of the body. There are three types of granulocytes that include:

Neutrophils: The neutrophils contain a single nucleus which consists of multiple lobes. They are the most abundant number of granulocytes present in the blood. They are found to be chemically attracted to the bacteria and they migrate through tissues to reach the infection site. They are phagocytic in nature and engulf the bacteria or the target cell for destroying it. During their release in the blood, they also act as lysosomes for digesting cellular macromolecules and are destroyed in the process.

Basophils: They are the least in the number found in the blood. The Basophils have a multi-lobed nucleus and contain heparin and histamine in their granules. The heparin is essential to keep the consistency of the blood so that it does not clot. The histamine acts to dilate the blood vessels which results to increase the permeability of the blood capillaries. This helps in increasing the flow of blood that assists in transporting leucocytes in the infected areas. They are also responsible for creating a response to an allergic reaction in the body.

Esonophils: The Eosinophils contain the double-lobed nucleus and due to their structure they appear as u-shaped in the smears of the blood. These are found in the connective tissues of the intestine and the stomach. They are also phagocytic in nature and they primary target is antigen-antibody complexes which are formed when the antibodies bonds with the antigens for identifying the substance to be eliminated and destroyed. They are seen to become more active during the allergic reaction and parasitic infection.

Agranulocytes have no granules and contain a larger nucleus than the granulocytes. There are mainly two types of agranulocytes:

Lymphocytes: The lymphocytes are the next common form of WBC after neutrophil to be present in the blood. They are spherical in shape and contains a very little amount of cytoplasm and a large nucleus. The lymphocytes are of three types that include natural killer cells, T cells and B cells. The natural killer cells perform to offer non-specific immunity whereas the T cells and B cells offer specific immunity to the body.

Monocytes: The monocytes are the largest form of white blood cells present in the body. They consist of a single and large nucleus which is varied in shape but most often they appear in the shape of a kidney. They are migrated to the tissues from the blood where they develop into dendritic cells and macrophages. The macrophages are phagocytic in nature and are large cells which are present within the tissues. The dendritic cells are seen to be found at places where the tissues come into contact with the antigens transported from the external environment such as the skin, lungs, gastrointestinal tract and others. The dendritic cells are seen to primarily send antigenic information to the lymph organs and lymph nodes which helps in immunity development against the antigen. The dendritic cells are named so because they are similar in appearance with the dendrites of the nerve cells.

Comparison chart between Red Blood Cells (RBCs) and White Blood Cells (WBCs)

Red Blood Cells (RBCs)

White Blood Cells (WBCs)

They are named as Erythrocytes. They are named as Leucocytes
They are disc-shaped and biconcave in nature They are irregular in shape
Size ranges from 6-8µm diameter Size ranged from the 7-12µm diameter
The lifespan of RBCs is 120 days The lifespan of WBCs ranges from 4 to 30 days
Mature cells do not have nucleus Mature cells has a large central nucleus
They are red in colour They are colourless
RBCs are mainly produced from the bone marrow WBCs are produced from lymph nodes, red bone marrow, spleen, and others
Low RBC count is known as Anaemia Low WEB count is called Leukopenia
They help to transport oxygen and carbon dioxide to and from the blood. They mainly help to develop the body’s immunity system so that the infections are effectively fought.