Blood is a wonder liquid circulating throughout our body. It is not a mere liquid, it carries gases such as oxygen and carbon dioxide, has the ability to undergo diffusion of gases and absorbs various nutrients while dissolving essential molecules. Blood contains 4 major components:

  • Red blood cells(RBCs) or Erythrocytes
  • White blood cells(WBCs) or Leukocytes
  • Platelets
  • Plasma

Each component is crucial and carries out specialized functions. The RBCs contains a pigment called haemoglobin, responsible for the red color of the blood. It collects oxygen from the lungs and supplies it to all the tissues and collects deoxygenated blood from all parts of the body and unloads into the lungs. Platelets carry out haemostatic mechanisms and bring about coagulation of blood while plasma majorly contributes to fluid-like consistency of the blood.

White blood cells are the defense mechanisms of our body and can be classified into agranulocytes and granulocytes. Granulocytes contain organelles and cytoplasm, they are called so since the organelles emerge as granules which are usually coloured. It consists of eosinophils, basophils and neutrophils. Agranulocytes on the other hand, contain no granules. It consists of monocytes and lymphocytes.


  • Eosinophils – It has a nucleus which is split into two folds and large granules. They destroy allergens and harmful chemicals. They also release enzymes which disables parasites.
  • Neutrophils – Also called as PMN(Polymorphonuclear) as it varies in shape. They destroy bacteria by releasing chemicals harmful to the growth of bacteria.
  • Basophils – Contains granules behind which a neutral nucleus hides. It secretes histamine and heparin which increases the flow of blood to tissues and promotes mobility by preventing clotting respectively.


  • Monocytes – Constitutes for the largest formed elements. It contains clear and ample cytoplasm. They help differentiating macrophages, digest dead neutrophils and pathogens etc,. They also present antigens for activation of immune cells like lymphocytes.
  • Lymphocytes – They appear in all shapes – medium, small, large. Connective tissue sees lymphocytes. Sometimes, it also occurs in the bloodstream. They destroy virus-infected cells and other foreign cells. They live in the lymph nodes and help combat diseases by triggering the immune system to activate other cells. In addition, they secrete antibodies and maintain immune memory.

Just like WBCs, there are other organic molecules in our body called amino acids which carry out defense mechanisms in our body. They are a vital part of our nutrition and carry out important functions. Deficiency of one of these nutrients leads to disorders and imbalance in our body. Amino acids are the building blocks of proteins. They are a made up of a basic amino group(-NH2) and a carboxyl group (-COOH) and an organic group unique to each amino acid.

They are vital in promoting hair growth, repairing damaged tissues, help in the development of healthy bones, skin, teeth. It also helps eliminate wastes from the body as part of metabolism.

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White Blood Cells: Body’s Defense Mechanism