Multiple Choice
Which of the following is the most likely outcome if platelets could not release aggregating agents?
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17. The Blood
Platelets: Hemostasis
Multiple Choice
Which of the following is true regarding the extrinsic pathway of blood clotting?
A
The extrinsic pathway is independent of procoagulants.
B
The extrinsic pathway does not involve calcium ions.
C
The extrinsic pathway is slower than the intrinsic pathway of blood clotting.
D
The extrinsic pathway is triggered by tissue factor.
Verified step by step guidance1
Understand the context: Blood clotting involves a series of complex processes that prevent excessive bleeding when a blood vessel is injured. There are two main pathways: the intrinsic and extrinsic pathways, both leading to the formation of a blood clot.
Identify the role of the extrinsic pathway: The extrinsic pathway is initiated by external trauma that causes blood to escape from the vascular system. It is known for being a rapid response to injury.
Recognize the key components: The extrinsic pathway is triggered by the release of tissue factor (TF), also known as factor III, from damaged tissues. This is a crucial step that distinguishes it from the intrinsic pathway.
Clarify the involvement of calcium ions: Calcium ions (Ca²⁺) are essential for various steps in the blood clotting process, including the extrinsic pathway. They act as cofactors in the activation of several clotting factors.
Compare the speed of pathways: The extrinsic pathway is generally faster than the intrinsic pathway because it involves fewer steps and is directly activated by tissue factor, leading to a quicker formation of the clot.
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