Name the components of the formed elements in the blood and mention one major function of each of them.

(N/A) The formed elements in the blood are:
$(1)$ Erythrocytes (Red Blood Cells - $RBCs$):
They contain the red pigment haemoglobin,which is responsible for the transport of oxygen from the lungs to the tissues.
$(2)$ Leukocytes (White Blood Cells - $WBCs$):
These are colourless cells that lack haemoglobin. They are primarily involved in the body's immune defence mechanism. For example,neutrophils and monocytes are phagocytic,while lymphocytes are responsible for specific immune responses.
$(3)$ Platelets (Thrombocytes):
These are cell fragments produced from megakaryocytes. Their primary function is to release substances that promote blood coagulation (clotting) at the site of an injury.