Which of the following is NOT a formed element of blood?

Plasma is not considered a formed element of blood. Formed elements of blood refer specifically to the cellular components that are suspended in the plasma. These include erythrocytes (red blood cells), leukocytes (white blood cells), and platelets (cell fragments involved in clotting). Together, these components make up the cellular aspects of blood and are crucial for its functions, such as oxygen transport, immune response, and hemostasis.

Plasma, on the other hand, is a yellowish liquid that makes up about 55% of total blood volume and serves as a transport medium. It contains water, electrolytes, proteins, hormones, nutrients, and waste products. While plasma plays a vital role in the circulatory system, it is not classified as a formed element because it is not a cellular structure. Hence, recognizing the distinction between the liquid medium of plasma and the cellular formed elements is fundamental in understanding blood composition.