Extenuating Circumstances

The night before my Biology and Physics EMPA 3X exams my dad fell off his bike and suffered a serious head injury and I was the only point of call for my family at the time so I had to stay in hospital with him until 01:30 in the morning. I let my school know this and they told me that they would write to the exam board explaining my situation, I went in to school the next day and sat the exams and they went as well as they would have done. I was just wondering what kind of extenuating circumstances, if any, I can expect in this instance? I don't believe it affected me much, if at all, but say I was seriously affected by this, what would the exam board be able to do? Would it be as simple as giving me 10% extra marks, because that doesn't really seem fair.