首先，本科期间，比较了我所学的这些课程之后，我发现自己对消化方面的东西很感兴趣。再者，在我看来，研究生的专业方向，几乎会决定我将来的从业方向，所以我当时下定决心转专业的出发点是：将来能在自己比较感兴趣的行业工作的话，会更加好一点，而且我希望自己将来会在这行业有所作为。
还有，出于家庭因素的考虑，我希望自己能用自己的所学，帮助家人减轻疾病的痛苦，报答这些年来一直帮助我的亲人们！

Firstly,I carefully analyzed all the curriculums I've had during my undergraduate study and found that the courses related to digestion was where I've located my interest.Then,in my opinion the major I choose for my graduate study would also be the major of my future career.Accordingly when I decided to have my major changed,I simply wanted to be involved in something I was interested in and I believed that working in my favorate field,in which I hope I will at least achieve something, would guarantee myself a more prosperous future.
Furthermore,due to my family background,to alleviate the surfferings of my ill familiy members with what I've learnt would be quite important for me.I've been receiving solid supports from them for so many years and now it's time for me to pay them back.