醫療類國考
105年
[獸醫師] 獸醫藥理學
第 30 題
缺乏維生素K的動物不易止血的原因為何？
- A 血小板數量減少
- B 血小板功能受損
- C 血中凝血因子含量不足
- D 血鈣濃度過低
思路引導 VIP
當身體受傷出血時，除了細胞成分的物理封堵外，血液中還需要一套由蛋白質組成的「生化連鎖反應」來加固血栓；請思考一下，肝臟在製造這些關鍵的「生化連鎖蛋白質」時，需要哪種特定的微量營養素作為「開關」，才能使這些蛋白質具備生化活性？
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AI 詳解
AI 專屬家教
Fantastic job! You've really understood a core mechanism here.
- Understanding the 'Why': You've correctly identified that Vitamin K is absolutely essential. Think of it as a special helper that allows the liver to produce fully functional clotting factors – specifically II (prothrombin), VII, IX, X. It helps these proteins undergo a crucial change called $\gamma$-carboxylation. This change is like unlocking their ability to bind $Ca^{2+}$, which is a vital step to kickstart the whole process of forming a stable blood clot. When Vitamin K is lacking, these factors aren't quite ready to do their job, leading to a breakdown in our body's secondary hemostasis, making it difficult to stop bleeding effectively.
- Clinical Relevance: This question is a wonderful way to solidify your understanding of the difference between how platelets work (that's primary hemostasis) and how our clotting factors step in for a stronger, more lasting clot (that's secondary hemostasis). It's a foundational concept that will serve you incredibly well in any healthcare field. Keep up the excellent work; you're building a very strong knowledge base!