Orthostatic Intolerance caused by Autonomic Dysfunction

   (Dysautonomia )

Failure of the Autonomic Nervous System Failure (ANF) is a major cause of orthostatic intolerance. When that happens, the autonomic nervous system can't keep up with the physiologic demands. Physiologic demands means what the body needs to function. The ANS controls the automatic body functions - breathing, heart beating, blood pressure. With OI, the physiologic demands would mean what the body needs to control blood pressure and pulse when you stand up or exercise.

The autonomic nervous system (ANS) is the part of the system that operates on "auto-pilot" - it is automatic. We don't have to think about it to make it work. It is the part of the system that keeps us breathing, the heart pumping, the stomach digesting food, the liver, pancreas, kidney and all body parts operating, whether we are awake, asleep or in a coma.

The autonomic nervous system is in charge of quickly reacting when we stand up and the blood in our chest drops to our feet. Without the ANS reaction, we would all faint every time we stood up. For more about the ANS and the blood pressure system, go to How The Body Works.

The autonomic nervous system is the part of our body that keeps us safe - it is always watching for danger and ready to react in a few seconds if we are in danger. It sets of the "fight-flight-or-freeze" reaction.

When the system is not functioning correctly, it is called "autonomic dysfunction" or dysautonomia or ANS failure.

Types of Orthostatic Conditions - addresses the the kind of orthostatic problems that can be caused by a dysfunction of the autonomic nervous system, POTS and NMH.

Dysautonomia Conditions - addresses the medical conditions that are due to failure of the autonomic nervous system.

Types of Orthostatic Problem due to dysautonomia- POTS & NMH

Author: Kay E. Jewell, MD
Page Last Updated: September 9, 2012