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 12

Textbook Question

Number the steps of hemostasis in order, putting 1 by the first event, 2 by the second, and so on.
The intrinsic/contact activation and extrinsic/tissue factor pathways produce factor Xa.
The clot retracts.
Thrombin converts fibrinogen to fibrin, and fibrin glues the plug together.
Platelets are activated, and the platelet plug forms.
Vasoconstriction and increased tissue pressure decrease blood flow through the vessel.
Tissue plasminogen activator activates plasmin, which degrades fibrin.
The common pathway produces thrombin.

Verified step by step guidance

Step 1: Vasoconstriction and increased tissue pressure decrease blood flow through the vessel. This is the vascular spasm phase, which helps minimize blood loss immediately after injury.

Step 2: Platelets are activated, and the platelet plug forms. This is the platelet phase, where platelets adhere to the damaged vessel and aggregate to form a temporary plug.

Step 3: The intrinsic/contact activation and extrinsic/tissue factor pathways produce factor Xa. These pathways are part of the coagulation cascade, which leads to the activation of factor Xa.

Step 4: The common pathway produces thrombin. Factor Xa converts prothrombin into thrombin, a key enzyme in the coagulation process.

Step 5: Thrombin converts fibrinogen to fibrin, and fibrin glues the plug together. Fibrin stabilizes the platelet plug, forming a solid clot.

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Key Concepts

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

Hemostasis

Hemostasis is the process that prevents and stops bleeding, or hemorrhage. It involves a complex interaction between blood vessels, platelets, and various proteins in the blood, leading to the formation of a stable blood clot. The process is typically divided into three phases: vascular spasm, platelet plug formation, and coagulation, each playing a crucial role in maintaining hemostatic balance.

Coagulation Pathways

The coagulation pathways consist of intrinsic and extrinsic pathways that converge to form a common pathway, ultimately leading to the production of thrombin and fibrin. The intrinsic pathway is activated by damage to the blood vessel, while the extrinsic pathway is triggered by tissue factor released from damaged tissues. Understanding these pathways is essential for grasping how factor Xa is produced and how clotting occurs.

Clot Retraction and Fibrinolysis

Clot retraction is the process by which a blood clot contracts to reduce its size, which helps to stabilize the clot and bring the edges of the wound closer together. Fibrinolysis is the subsequent process that involves the breakdown of fibrin in the clot, primarily through the action of plasmin. This balance between clot formation and dissolution is vital for normal healing and preventing excessive clotting.

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Textbook Question

Define hemostasis

List the three major phases of coagulation. Explain what initiates each phase and what the phase accomplishes

In what general way do the intrinsic and extrinsic mechanisms of clotting differ?

Which ion is essential to virtually all stages of coagulation?

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Textbook Question

Why is aspirin sometimes prescribed for the prevention of vascular problems?

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Textbook Question

A test for prothrombin time is used to identify deficiencies in the extrinsic clotting pathway; prothrombin time is prolonged if any of the factors are deficient. A test for activated partial thromboplastin time is used in a similar fashion to detect deficiencies in the intrinsic clotting pathway. Which factor would be deficient if a person had a prolonged prothrombin time but a normal partial thromboplastin time?

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Textbook Question

Almost half of our vitamin K is synthesized by bacteria that inhabit the large intestine. Based on this information, how could taking a broad-spectrum antibiotic for a long time cause frequent nosebleeds?

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Textbook Question

How do the intrinsic/contact activation and extrinsic/tissue factor coagulation pathways differ? How are they similar?

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Textbook Question

What are the overall goals of the common pathway of coagulation?

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Textbook Question

Which of the following is not an anticlotting agent produced by endothelial cells?