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 9

Textbook Question

_ and __ affect almost every aspect of the clotting process.
(a) Calcium, vitamin K
(b) Calcium, vitamin B12
(c) Sodium, vitamin K
(d) Sodium, vitamin B12

Verified step by step guidance

Step 1: Understand the clotting process. Blood clotting, or coagulation, is a complex process involving a cascade of reactions that lead to the formation of a fibrin clot. This process requires various clotting factors, enzymes, and cofactors.

Step 2: Recognize the role of calcium in clotting. Calcium ions (Ca²⁺) are essential for several steps in the clotting cascade, including the activation of certain clotting factors and the stabilization of fibrin clots.

Step 3: Identify the role of vitamin K. Vitamin K is crucial for the synthesis of clotting factors II (prothrombin), VII, IX, and X in the liver. Without vitamin K, these clotting factors cannot function properly, impairing the clotting process.

Step 4: Eliminate incorrect options. Sodium and vitamin B12 are not directly involved in the clotting process. Sodium is important for fluid balance and nerve function, while vitamin B12 is essential for red blood cell production and DNA synthesis, but neither plays a role in coagulation.

Step 5: Conclude that calcium and vitamin K are the correct answer because they directly affect almost every aspect of the clotting process.

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Key Concepts

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

Clotting Process

The clotting process, or coagulation, is a complex series of events that lead to the formation of a blood clot. This process involves various proteins known as clotting factors, which work together to stop bleeding by forming a stable fibrin mesh over a wound. Understanding the stages of clotting, including vascular spasm, platelet plug formation, and coagulation, is essential for recognizing how different substances influence this critical physiological response.

Calcium in Coagulation

Calcium ions (Ca2+) play a vital role in the coagulation cascade, acting as a cofactor for several clotting factors. They are necessary for the activation of prothrombin to thrombin, which is crucial for converting fibrinogen into fibrin, the protein that forms the mesh of a blood clot. Without adequate calcium levels, the clotting process can be severely impaired, leading to increased bleeding risk.

Vitamin K and Coagulation

Vitamin K is essential for the synthesis of several key clotting factors, including prothrombin and factors VII, IX, and X. It acts as a coenzyme in the post-translational modification of these proteins, enabling them to bind calcium ions and function effectively in the clotting process. A deficiency in vitamin K can lead to bleeding disorders, highlighting its critical role in maintaining hemostasis.