Which component of blood consists of small cell fragments that aid in coagulation?

• A. Blood plasma
• B. Platelets
• C. White blood cells
• D. Red blood cells

Answer: (B)

Platelets are the small cell fragments that help stop bleeding. They come from larger bone marrow cells called megakaryocytes and circulate in the blood as tiny, anucleate pieces. When a blood vessel is injured, platelets quicky stick to exposed surfaces, become activated, and release chemicals that recruit more platelets. They also provide a surface for the clotting factors in the plasma to assemble a fibrin mesh, forming a stable clot. This platelet-led plug is the first crucial step in stopping bleeding, working alongside the plasma-based clotting cascade. The other components—blood plasma is the fluid with nutrients and clotting factors, white blood cells fight infections, and red blood cells carry oxygen—do not perform this immediate plug-and-seal function.