Final answer:
Blood plasma contains coagulation factors that are necessary for blood clotting; serum is plasma with these clotting factors removed and thus does not clot. Plasma is used when clotting functionality needs to be assessed, while serum is used for other types of blood analyses.
Step-by-step explanation:
The liquid component of blood is called plasma, which consists of 90 percent water, along with substances required for maintaining the body's pH, osmotic load, and for protecting the body. This includes coagulation factors and antibodies. When we talk about blood clotting, the process involves platelets and coagulation factors triggering the conversion of the soluble protein fibrinogen into the insoluble protein fibrin, which forms a plug at a wound site. This process is crucial for preventing blood loss and allowing wounds to heal.
By contrast, serum is the part of blood plasma from which the clotting factors have been removed. Serum does not clot because it lacks these coagulation factors. This is summarized by the equation: plasma − fibrinogen = serum. In a clinical setting, serum is what remains after blood clots and is separated during processing. In conclusion, the main difference is that plasma contains coagulation factors necessary for clot formation, while serum is plasma without these factors, and therefore, does not clot.