Blood Composition and Hemostasis - Anatomy and Physiology
- Which plasma protein lets platelets adhere to exposed collagen in a damaged vessel wall?
- Von Willebrand factor, which bridges collagen and platelet surface receptors.
- What does the hematocrit measure?
- The percentage of whole blood volume occupied by red blood cells.
- How does serum differ from plasma?
- Serum is the fluid left after blood clots, so it lacks fibrinogen and other consumed clotting factors.
- Which enzyme breaks down fibrin during fibrinolysis?
- Plasmin, formed from plasminogen by activators such as tissue plasminogen activator (tPA).
- The liver needs vitamin K to make which clotting factors?
- Factors II (prothrombin), VII, IX, and X.
- Which enzyme converts fibrinogen into fibrin?
- Thrombin, which is generated from prothrombin.
- About what percentage of whole blood volume is plasma, and what percentage is formed elements?
- About 55 percent plasma and 45 percent formed elements, nearly all of which are red blood cells.
- Which is the most abundant plasma protein, and what is its main role?
- Albumin. It provides most of the plasma colloid osmotic pressure that holds fluid in the vessels.
- What triggers the extrinsic pathway of coagulation?
- Tissue factor (factor III), released from damaged tissue outside the blood.
- Activation of which clotting factor begins the common pathway of coagulation?
- Factor X. The intrinsic and extrinsic pathways both converge on its activation.
- Which is the most abundant type of white blood cell in normal blood?
- The neutrophil, about 50 to 70 percent of leukocytes.
- What are the three phases of hemostasis, in order?
- Vascular spasm, platelet plug formation, and coagulation (blood clotting).