Blood Constituents

BloodAi??is made up of cells in a watery base, called plasma. There are three major types of cells in blood ai??i?? red blood cells (RBCs), while blood cells (WBCs) and platelets.

  • Red Blood Cells (RBCs) or erythrocytes
  • White Blood cells (WBCs) or leukocytes
  • Platelets or thrombocytes

These cells float around and are carried through the body in a fluid known as plasma.

Blood is a fluid that flows through the body. It is thicker than water and is salty to taste. There are about 10.6 pints of blood that circulates through the body of a normal adult. Read the following blood constituents:

Red blood cells:

Red blood cells are also known as erythrocytes, carry oxygen to various parts of the body.

  • They are the most in number, constituting about 40-45% of blood. Their structure is like that of dough nuts.
  • They contain haemoglobin, which contains iron and protein and helps carry oxygen throughout the body.
  • The iron present in RBCs makes blood appears red in color.

Ai??White blood cells:

  • They are also called leukocytes, They protect body systems from infections, diseases by fighting viruses, bacteria and other such harmful invasions.
  • They are of three types, namely, monocytes, lymphocytes and granulocytes.
  • Granulocytes are of three types ai??i?? neutrophils, basophils and eosinophils.
  • Neutrophils destroy invasive bacteria by ingesting and then digesting them.
  • Eosinophils destroy parasites and play a part in allergic reactions.
  • Basophils also play a part in allergic reactions, but their role is not yet clear.
  • Lymphocytes are extremely important to the immune system. They are of two types ai??i?? T cells and B cells.
  • T cells tell the immune system about invasions and external activity.
  • B cells produce antibodies that destroy foreign harmful bodies.
  • Monocytes are the largest of WBCs which become even bigger on entering tissues and are called macrophages.
  • They ingest foreign bodies and help rid the body of damaged and dead cells.


  • They are also called thrombocytes, help in clotting of blood and also help prevent internal bleeding.
  • They are essential in maintaining wear and tear of the body.
  • They are important in stopping bleeding in case of an external wound or abrasion.
  • They are shaped like plates when inactive and that is the reason why they are called platelets. They are the smallest of the blood cells.


  • This is the fluid in which these cells are present and which carries these cells all over the body.
  • It is made up of 90% water.
  • The rest 10% consists of the cells mentioned above along with proteins, vitamins, minerals, glucose, hormones and many other essential nutrients.