The document discusses the components and functions of blood. Blood has three main functions: transportation, regulation, and protection. Whole blood consists of blood plasma and formed elements, which include red blood cells, white blood cells, and platelets. Red blood cells contain hemoglobin and transport oxygen, white blood cells help fight infection, and platelets form clots to stop bleeding. Blood types are determined by antigens on red blood cells, and Rh disease can occur if an Rh- mother has an Rh+ baby.