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 7

Textbook Question

The following is a list of the phases involved in the process of hemostasis:
Coagulation
Fibrinolysis
Vascular spasm
Retraction
Platelet phase
The correct sequence of these phases is:
(a) 5, 1, 4, 2, 3
(b) 3, 5, 1, 4, 2
(c) 2, 3, 5, 1, 4
(d) 3, 5, 4, 1, 2
(e) 4, 3, 5, 2, 1

Verified step by step guidance

Step 1: Understand the concept of hemostasis, which is the process by which the body stops bleeding and repairs damaged blood vessels. It involves several sequential phases.

Step 2: Begin with the first phase, vascular spasm. This is the immediate constriction of blood vessels to reduce blood flow to the injured area.

Step 3: Next is the platelet phase, where platelets adhere to the damaged vessel and aggregate to form a temporary plug.

Step 4: The coagulation phase follows, involving a cascade of reactions that lead to the formation of a stable fibrin clot. This stabilizes the platelet plug.

Step 5: After the clot is formed, retraction occurs, where the clot contracts to bring the edges of the wound closer together, followed by fibrinolysis, the breakdown and removal of the clot once the vessel is repaired.

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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 that form a clot. The process is typically divided into three main phases: vascular spasm, platelet plug formation, and coagulation, followed by fibrinolysis to break down the clot once healing has occurred.

Coagulation Cascade

The coagulation cascade is a series of biochemical reactions involving clotting factors that lead to the formation of a stable blood clot. This cascade is triggered by vascular injury and involves intrinsic and extrinsic pathways that converge to produce fibrin, which stabilizes the platelet plug. Understanding this cascade is crucial for determining the correct sequence of hemostatic phases.

Platelet Phase

The platelet phase is the initial response to vascular injury, where platelets adhere to the exposed collagen of the damaged vessel and aggregate to form a temporary 'platelet plug.' This phase is essential for rapid hemostatic response and is followed by the coagulation phase, where the clot is stabilized. The sequence of events in this phase is critical for understanding the overall process of hemostasis.