Blood Components

Blood Components

Components of Blood

Red Blood Cells

  • Red blood cells or erythrocytes are biconcave disc-shaped cells without a nucleus.
  • They carry oxygen from the lungs to body cells and carbon dioxide from the cells to the lungs.
  • Haemoglobin, the red pigment in red blood cells, binds with oxygen to form oxyhaemoglobin in the lungs. This pigment provides the red colour.

White Blood Cells

  • Leukocytes, commonly known as white blood cells, play a major role in defending the body against diseases.
  • They can change their shape to engulf microorganisms.
  • The two primary types of leukocytes are phagocytes (cells that ingest harmful foreign particles) and lymphocytes (cells that produce antibodies against these particles).


  • Platelets are small fragments of cells that initiate blood clotting.
  • When a blood vessel is damaged, platelets stick to the damaged area and release chemicals that activate enzymes in the blood to form a clot.
  • The clot prevents further bleeding and seals the damage.


  • Blood plasma is a straw-coloured liquid that carries dissolved substances around the body.
  • Plasma transports various components including hormones, nutrients, waste products, gases like oxygen and carbon dioxide, and heat.
  • It also carries the cells and platelets which make up the solid part of the blood.


  • Antibodies are proteins produced by a type of white blood cell, the lymphocytes, in response to the presence of foreign substances, known as antigens.
  • Each antibody is specific to one particular antigen. Once it meets with the specific antigen, it neutralises or destroys it.
  • Antibodies help the body to build immunity against diseases.


  • Antigens are substances, often proteins, that are recognised by the immune system as foreign and trigger an immune response.
  • They can be found on the surface of cells, viruses, fungi, or bacteria.
  • The body produces specific antibodies to try and neutralise or destroy each different antigen.