Which of the following is a protein present in blood plasma?
A.
Monocytes
B.
Platelets
C.
Fibrinogen
D.
Lymphocytes
The correct answer and Explanation is :
The correct answer is C. Fibrinogen.
Fibrinogen is a key protein present in blood plasma. It plays a crucial role in the blood clotting process, which is vital for preventing excessive bleeding when blood vessels are injured. Here’s a detailed explanation:
Blood Plasma Components
Blood plasma is the liquid component of blood in which cells and proteins are suspended. It constitutes about 55% of the total blood volume and is primarily composed of water (about 90%). The remaining 10% consists of various dissolved substances, including proteins, electrolytes, nutrients, hormones, and waste products.
Role of Fibrinogen
Fibrinogen is one of the major proteins in blood plasma, accounting for about 2-4 grams per liter of plasma. It is synthesized in the liver and released into the bloodstream. The primary function of fibrinogen is to aid in blood clotting. When a blood vessel is injured, fibrinogen is converted into fibrin through a series of enzymatic reactions involving thrombin. Fibrin forms a mesh-like structure that traps blood cells and platelets, creating a stable blood clot that helps to seal the wound and prevent further bleeding.
Comparison with Other Options
- Monocytes and Lymphocytes are types of white blood cells (leukocytes) found in blood, but they are not proteins. Monocytes are involved in immune responses and can differentiate into macrophages that engulf pathogens. Lymphocytes are crucial for adaptive immunity, including T-cells and B-cells, which recognize and respond to specific antigens.
- Platelets are small, cell-like fragments involved in clotting but are not proteins. They help in the formation of clots by adhering to the site of vascular injury and aggregating with fibrin.
Summary
Fibrinogen is an essential plasma protein involved in the coagulation cascade, making it vital for maintaining hemostasis. Its conversion to fibrin is a critical step in forming a blood clot, ensuring that bleeding is controlled and healing can proceed.