Blood without blood cells and fibrinogen is called?

NHM UP Staff Nurse - 2017

Applied Physiology

Medium

Appeared in: NHM UP Staff Nurse - 2017

Explanation

Serum is the liquid component that remains after blood has been allowed to clot.
The process of clotting consumes coagulation factors, most notably fibrinogen, which is converted into a solid fibrin clot.
Therefore, serum is defined as blood plasma from which fibrinogen and other clotting factors have been removed.
The question asks for blood without cells and without fibrinogen, which is the precise definition of serum.

Option A: Lymph is the fluid of the lymphatic system, which is separate from the circulatory system. While it originates from plasma, its composition is different, containing less protein.
Option C: Plasma is the liquid component of blood before clotting. It is obtained by treating blood with an anticoagulant. Crucially, it still contains fibrinogen.
Option D: Platelets (thrombocytes) are small, irregular cell fragments, not a fluid. They are a solid component of blood and are essential for initiating the clotting process.

Clinical Relevance

Nursing practice connection: Knowing Composition of blood and its fluid components (Plasma vs. Serum) helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses must understand the difference between serum and plasma because it dictates which type of blood collection tube to use for specific laboratory tests. Using the wrong tube leads to inaccurate results and can delay diagnosis and treatment.
Serum is required for many chemistry, immunology, and serology tests because the absence of fibrinogen and other clotting factors prevents interference with the assay.
Plasma is required for coagulation studies (like PT/INR and aPTT) because the test's purpose is to measure the activity of the clotting factors (including fibrinogen) present in the plasma.

How to Approach the Question

First, break down the question into its core components: the starting material is 'blood', and two things are removed: 'blood cells' and 'fibrinogen'.
Recall the basic composition of blood. When you remove the cellular components (RBCs, WBCs, platelets) from whole blood, the remaining liquid is called plasma.
Next, consider the role of fibrinogen. Fibrinogen is a protein dissolved in plasma that is essential for blood clotting.
The question specifies that fibrinogen is also removed. The process that removes fibrinogen from plasma is clotting. The liquid left over after clotting is called serum.
Therefore, blood without cells and without fibrinogen is serum.
Evaluate the options based on this logic: Lymph is a different body fluid. Plasma contains fibrinogen. Platelets are cells. Serum is the only option that fits the description.

Concept Tested & Keywords

Concept Tested: Composition of blood and its fluid components (Plasma vs. Serum)
Stem keywords: blood, blood cells, fibrinogen
Lead-in keywords: is called
Negative lead-in flag: false

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