If you go to the National Dysautonomia Research Foundation ndrf.org and click on learn more scroll down to PDF format online it has an excellent, easy to understand booklet about the ANS system, what it does, about the vegas nerve etc
http://www.ndrf.org/NDRF%20Patient%20Handbook/SecA_pp17-58.PDF
if you are having hypotension and bradycardia which most times are due to a mixed signal in the autonomic nervous system/brain/heart connection and can be treated with extra fluids, salt and Midodrine or Florinef, compression stocking and some others
here's some more info from the Dysautonmia forum here:
http://www.medhelp.org/health_pages/Neurological-Disorders/Autonomic-Dysfunction-FAQ/show/181?cid=196 4. What is a Vasovagal Reflex? 5. What are some of the more common symptoms of an autonomic dysfunction
anxiety may just be part of the ANS with mixed signals about adrenaline (epinephrine)
hopefully this makes sense...I have brain fog horribly lately and sometimes miss explaining things =)