Blood composition and function

Blood is red blood cells, white blood cells, platelets and plasma, such as composed of several components, red blood cells, white blood cells and platelets are produced in the bone marrow, and then enter the blood. Red blood cells can carry oxygen for use in human tissue respiration, while the white blood cells can resist bacteria and other diseases, the human body are the most powerful defense system. Platelet can hemorrhage in the injured, the promotion of blood coagulation and reduce the possibility of loss of blood. Plasma contains many antibodies, can resist diseases.