I have been thinking about feelings of anxiety and worrisome thoughts, which for the purposes of this discussion I will better define:

1) Feelings of anxiety are the internal feelings that is are caused body's actual physical response.  For me it is felt as a throbbing of some sort, and for others they might have shortness of breath or some other physical feeling.

2) Worrisome thoughts are those internal thoughts that flicker in your mind, and likely begin with what if, which you then associate with, and perhaps even merge with as if they are actually happening now.

I guess I always thought that the feelings of anxiety served as a string around my finger not to stop thinking about something important, but was reading earlier that in fact it is the opposite, that thoughts create the feelings.  Of course, a further option they didn't mention is that thoughts create feelings that in turn create more thoughts.  

Does anyone have any scientific sources that discuss the above question they can point me to so I can learn a little more about it?  Thanks!