Answer :
Final answer:
The question pertains to blood clotting pathways, specifically the intrinsic and extrinsic pathways. The extrinsic pathway is initiated by damaged tissues, while the intrinsic pathway is slower and relies on factors within the bloodstream. The correct answer to the multiple-choice question is that the extrinsic pathway starts with factors from damaged tissues.
Explanation:
Pathways for Blood Clotting
Blood clotting involves two main pathways: the extrinsic pathway and the intrinsic pathway.
Extrinsic Pathway
The extrinsic pathway is triggered by damage to surrounding tissues, such as in a traumatic injury. When damage occurs, extravascular cells release factor III (thromboplastin), leading to a quick cascade of events resulting in blood clotting. This pathway acts rapidly, completing its function in a matter of seconds.
Intrinsic Pathway
Conversely, the intrinsic pathway, also known as the contact activation pathway, is longer and more complex. It typically begins when factor XII encounters negatively charged surfaces or foreign materials, starting a series of reactions involving several clotting factors present in the blood, ultimately leading to the formation of a clot. This pathway takes more time to activate compared to the extrinsic pathway.
Common Pathway
Both pathways converge at the common pathway, where factor X is activated, leading to the transformation of prothrombin into thrombin, which then converts fibrinogen into fibrin, stabilizing the clot.
Now, addressing the multiple-choice statements:
- The intrinsic pathway takes less time than the extrinsic pathway. (Incorrect)
- The intrinsic and extrinsic pathways require sodium. (Incorrect)
- The extrinsic pathway is started by factors from damaged tissues. (Correct)
- The intrinsic pathway requires the same clotting factors as the extrinsic pathway. (Incorrect)
The correct statement is: The extrinsic pathway is started by factors from damaged tissues.
Learn more about Blood Clotting here:
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