Anatomy and Physiology II Practice Test

Blood clotting is primarily dependent on which vitamin?

1. Vitamin A

2. Vitamin D

3. Vitamin E

4. Vitamin K

The correct answer is: Vitamin K

Blood clotting is primarily dependent on vitamin K, which plays a crucial role in the synthesis of certain proteins required for blood coagulation. This vitamin is essential for the production of clotting factors such as prothrombin and other proteins in the liver that are necessary for the coagulation cascade. Without sufficient vitamin K, the body cannot effectively form clots, leading to an increased risk of excessive bleeding. Vitamin K exists in two main forms: K1 (phylloquinone), found in leafy greens and vegetables, and K2 (menaquinone), found in fermented foods and animal products. The adequate intake of vitamin K ensures that the clotting factors are produced at levels sufficient to maintain hemostasis, which is critical for preventing blood loss after injuries or during surgical procedures. In contrast, vitamins A, D, and E do not play direct roles in the clotting process. Vitamin A is primarily involved in vision and immune function, vitamin D is crucial for calcium metabolism and bone health, and vitamin E acts as an antioxidant. Therefore, while these vitamins are important for various bodily functions, they do not directly influence blood coagulation like vitamin K does.