NHA Phlebotomy Certification Practice Exam

What is the liquid portion of blood called?

1. Hematocrit

2. Serum

3. Cytoplasm

4. Plasma

The correct answer is: Plasma

The liquid portion of blood is referred to as plasma. Plasma constitutes about 55% of total blood volume and is a vital component as it serves several important functions. It is primarily composed of water, electrolytes, proteins, hormones, and waste products. Plasma acts as a medium for transporting nutrients, gases, and waste products throughout the body. It plays a crucial role in maintaining blood pressure and volume, providing essential proteins for blood clotting and immunity, and facilitating the distribution of heat. Unlike serum, which is obtained after the blood has clotted and does not contain clotting factors, plasma retains these factors. This characteristic allows plasma to support coagulation processes, making it critical for wound healing and maintaining hemostasis. Hematocrit refers to the proportion of blood volume that is occupied by red blood cells and does not represent the liquid component. Cytoplasm, on the other hand, pertains to the fluid within cells, rather than a part of blood. Thus, plasma is the correct answer, as it accurately describes the liquid portion of blood that serves a fundamental role in the circulatory system.