Autonomic nervous system

 Organ system: Peripheral nervous system

Definition: The component of the peripheral nervous system which carries involuntary, subconscious commands to the muscles and sweat glands of the body.

 

Divisions

By function

• Sympathetic nervous system
• Parasympathetic nervous system

By origin

• Cranial nerves
• Spinal nerves

The sympathetic and parasympathetic nerves are constantly transmitting signals (known as "sympathetic tone", "vagal tone", etc.) to maintain a dynamic balance in their target tissues. This 'tug of war' shifts towards sympathetic or parasympathetic effects as necessary.

Pathology

• Autonomic nervous system diseases

Removal of one system leaves the other system completely unopposed. For this reason, patients with spinal injuries may develop "autonomic dysfunction". Normal stimulation of the remaining system can cause life-threatening effects.