Blood is an important tissue of the body performing vital functions of nutrient transport, immunity and maintenance of homeostasis. Heart and blood vessels works continuously to circulate blood throughout the body in non-stop manner for whole of the life. Blood performs important functions such as oxygen & nutrient transport, body defense through phogocytosis and immune functions, thermoregulation, fluid balance, clotting etc. Blood groups are involved in blood transfusion purpose. Lymphatic system restores the fluid and osmotic balance of body by returning surplus tissue fluid and proteins from tissues to blood.