Nervous. Very.

I am feeling very nervous for my Anatomy workshop that starts tomorrow. Why? It's only a workshop...I'm there to learn, right? My ego has kicked into hyper-gear, and I'm worried I'll look like an amateur. Duh. That's what I am, right? I've only been practicing yoga for 3.5 years. I did my first teacher training only two years ago. Of course, I'm not going to know as much as the people who are hosting the workshop. They're there to teach me, and I'm there to learn. I've got to let this nervousness flow through me.

Can anyone explain to me the "science" behind the feeling of nervousness? What happens to our bodies when we are nervous? I would be very interested.