Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

17. The Blood

Platelets: Hemostasis

Anatomy & Physiology

17. The Blood

Platelets: Hemostasis

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Problem 16

Textbook Question

What is the difference between prothrombin and thrombin?

Verified step by step guidance

Prothrombin is a plasma protein produced by the liver and is inactive in its original form. It plays a crucial role in the blood clotting process and is dependent on vitamin K for its synthesis.

Thrombin is the active enzyme form of prothrombin. It is generated during the coagulation cascade when prothrombin is converted into thrombin by the action of the enzyme prothrombinase.

The conversion of prothrombin to thrombin occurs in the presence of calcium ions (Ca²⁺) and clotting factors, specifically Factor Xa and Factor Va, which form the prothrombinase complex.

Thrombin acts as a key enzyme in the clotting process by converting fibrinogen, a soluble plasma protein, into insoluble fibrin strands that form the structural framework of a blood clot.

In summary, prothrombin is the inactive precursor, while thrombin is the active enzyme that facilitates the formation of a blood clot by catalyzing the conversion of fibrinogen to fibrin.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Prothrombin

Prothrombin is a glycoprotein produced by the liver that plays a crucial role in blood coagulation. It is a precursor to thrombin and is converted into thrombin through the action of the enzyme prothrombinase during the coagulation cascade. Prothrombin is essential for the formation of blood clots, as it helps in the conversion of fibrinogen to fibrin.

Thrombin

Thrombin is an enzyme that is formed from prothrombin during the coagulation process. It is a key player in hemostasis, as it catalyzes the conversion of fibrinogen into fibrin, which forms the structural basis of a blood clot. Thrombin also activates platelets and other coagulation factors, amplifying the clotting response.

Coagulation Cascade

The coagulation cascade is a complex series of events involving various proteins and enzymes that lead to blood clot formation. It consists of intrinsic and extrinsic pathways that converge to activate prothrombin into thrombin. Understanding this cascade is essential for grasping how prothrombin and thrombin function in the body, as well as the overall process of hemostasis.