Final answer:
Serum lacks fibrinogen, one of the blood coagulation factors, differentiating it from blood plasma. Serum is used in lab tests due to the absence of clotting factors and has functions similar to interstitial fluid, including transporting nutrients, hormones, and antibodies.
Step-by-step explanation:
Serum is identical to plasma except it does not contain fibrinogen, which is one of the coagulation factors. The serum also contains antibodies, specialized proteins that are important for defense against viruses and bacteria. Lipids, including cholesterol, are also transported in the serum, along with various other substances including nutrients, hormones, metabolic waste, plus external substances, such as, drugs, viruses, and bacteria.
Blood plasma is the liquid component of blood that contains various substances including water, electrolytes, nutrients, hormones, antibodies, and coagulation factors. Serum is the fluid that remains after the clotting proteins, such as fibrinogen, has been removed from plasma, resulting in a substance that lacks these blood coagulation factors. This is why serum is used in various lab tests, as the absence of clotting factors does not hinder the analysis of other components. Characteristics of serum also include its role similar to interstitial fluid, providing necessary ions for muscle and nerve function, maintaining pH and osmotic balance, and transporting antibodies, lipids, and other substances throughout the body.