Final answer:
The matrix of blood is called plasma, which is a mostly water-based liquid that contains various dissolved substances essential for the transport and function of the formed elements in the blood.
Step-by-step explanation:
The matrix of blood is called plasma. Blood is a fluid connective tissue composed of formed elements – erythrocytes (red blood cells), leukocytes (white blood cells), and platelets – and a fluid extracellular matrix called plasma; it's a component of the cardiovascular system. This matrix, which is mostly water, contains dissolved proteins, electrolytes, glucose, lipids, and gases, which facilitate the circulation of the formed elements throughout the body.