The cellular elements—referred to as the formed elements —include red blood cells (RBCs) , white blood cells (WBCs) , and cell fragments called platelets . The extracellular matrix, called plasma , makes blood unique among connective tissues because it is fluid.

The primary function of blood is to deliver oxygen and nutrients to and remove wastes from body cells, but that is only the beginning of the story. Recall that blood is a connective tissue.

blood — liquid connective tissue composed of formed elements—erythrocytes, leukocytes, and platelets—and a fluid extracellular matrix called plasma; component of the cardiovascular system. formed elements — cellular components of blood; that is, erythrocytes, leukocytes, and platelets. plasma — in blood, the liquid extracellular matrix composed mostly of water that circulates the formed elements and dissolved materials throughout the cardiovascular system. white blood cells (WBCs) — (also, leukocytes) one of the formed elements of blood that provides defense against disease agents and foreign materials.

Be able to identify the primary functions of blood in transportation, defense, and maintenance of homeostasis; name the fluid component of blood and the three major types of formed elements, and identify their relative proportions in a blood sample; discuss the unique physical characteristics of blood.