What is plasma?

• A. The formed elements including red blood cells, white blood cells, and platelets
• B. The liquid component of blood
• C. The plasma proteins only
• D. The cellular portion that carries oxygen

Answer: (B)

Plasma is the liquid component of blood—the watery medium in which the formed elements float. It is mostly water, but it also carries dissolved substances such as electrolytes, nutrients, hormones, waste products, and plasma proteins. Among those proteins are albumin, globulins, and fibrinogen, which support functions like fluid balance, immune responses, and blood clotting. The key idea is that plasma is the fluid part, not the cellular elements.

The cellular portion—red blood cells, white blood cells, and platelets—makes up the formed elements, not plasma. Saying plasma contains only plasma proteins ignores the other dissolved substances. The cellular portion that carries oxygen refers to red blood cells, which is separate from plasma.