Transfer of blood from one person to another is called blood transfusion. Ill or seriously injured people may need it. But compatibility of the blood groups is checked first. People with blood group AB are called universal recipients and people with blood group 0 are called universal donors.
Concept: Blood Vessels of the Heart: Vena Cavae, Pulmonary Veins, Pulmonary Trunk, Aorta, Coronary Artery and Vains