This is because the process called hemostasis, literally meaning to stop the flow of blood, is impaired.

这是因为血友病患者的止血过程受损，即其凝血功能出现障碍。

And also how he knows exactly that he's a hemophiliac.

还有他是如何确切知道自己是血友病患者的。

Treatment for hemophilia A and B are done with injections of the missing or nonfunctional clotting factor.

治疗血友病A和B的方法通常是注射那些缺失或失活的凝血因子。

In the family of disorders known as hemophilia, a patient can usually complete the first two steps of hemostasis just fine, but they can't make an effective fibrin clot.

在被称为血友病的疾病家族中，病人通常可以很好地完成止血的步骤，但是他们不能制造有效的纤维蛋白凝块。

Believe it or not, this is a somewhat simplified version of the coagulation cascade; but, it contains all of the key parts needed to understand hemophilia.

总之，这就是简化版的凝血级联反应，已经包含了解血友病病所需的关键部分。

To prevent complications from an existing blood or bleeding disorder, such as sickle cell disease, thalassemia, or anaemia caused by kidney disease, haemophilia, or von Willebrand disease.

预防现有血或出血性疾病的并发症，如镰状细胞病、地中海贫血或由肾脏疾病、血友病或血管性血友病引起的贫血。

By far the most common of these are deficiencies of factor VIII which gives rise to factor VIIIa and is stabilized by another factor called von Willebrand factor.

目为止，大多数的血友病通常是因子VIII缺乏症；因子VIII能转变为因子VIIIa，并被血管性血友病因子（vWF）固定。

Signs and symptoms hemophilia A and B are nearly clinically identical, which makes sense since factors VIIIa and IXa work together in the coagulation cascade to activate factor X.

血友病A和B的体征和症状在临床上几乎相同，也说得通，因为因子VIIIa和IXa在凝血级联反应中，共同作用以激活因子X。

Diagnosis of hemophilia A and B usually starts with lab tests including a platelet count which is usually normal, a prothrombin (PT) time, and a partial thromboplastic (PTT) time.

血友病A和B的诊断通常是进行实验检测，包括血小板计数（一般正常）、凝血酶原时间（PT），以及部分凝血活酶时间（PTT）。