Dysautonomia is a term used to describe multiple medical conditions that cause the malfunction of the Autonomic Nervous System. The Autonomic Nervous System is what controls the “automatic” functions of our bodies, the ones that we don’t think about, such as, heart rate, blood pressure, digestion, dilation and constriction of the pupils of the eye, kidney function, and temperature control.
http://www.dysautonomiainternational.org/