Blood is a connective tissue that circulates throughout the body. It is made up of a fluid medium called plasma in which float two types of blood cells, called red blood cells, white blood cells and cell fragments called blood platelets. Blood cells are manufactured in the bone marrow.

1. Red Blood Cells (RBC or Erythrocytes)

  • These are circular in shape, and contain a red coloured pigment called haemoglobin

  • No nucleus is present in RBC

  • RBC carry oxygen to tissues and bring back carbon dioxide from tissues

2. White Blood Cells (WBC or Leucocytes)

  • Since they carry no pigments, they are colourless

  • They have irregular shape

  • They prevent body from infections by eating up germs or by producing antibodies to fight antigens

3. Blood Platelets (Thrombocytes)

  • These are very small fragments of cells

  • They have no nuclei

  • They participate in clotting of blood

Functions of Blood

Blood carries nutrients, oxygen, carbon dioxide, hormones and waste material to the relevant parts of the body. Some medicines when taken in the body are also distributed through blood.