The Autonomic Nervous System or ANS is the branch of the Nervous System that controls and coordinates all the body’s automatic responses such as digestion, breathing, immune response, circulatory flow and blood pressure. It is divided into two parts, the sympathetic and parasympathetic nervous systems. Between them, they ensure that the body can function and remain balanced despite the many external and internal changes constantly affecting the body.
The sympathetic nervous system energizes our body, preparing us for action. It mainly stimulates the heart, lungs and major muscle groups. In its most extreme state it triggers the ‘fight or flight’ survival response. The physical structures of this system are the chains of sympathetic ganglia located beside the thoracic and lumbar vertebrae on either side of the spinal column. The parasympathetic nervous system calms and normalizes the body, restoring it to an optimal, resting state. It is the counterbalance to the Sympathetic system, stimulating the digestive system and skin and is most active when we are asleep or deeply relaxed.
The physical structures of this system are the vagus nerves, which can be affected at the base of the cranium and the sacral or pelvic nerve fibers, which leave the spinal cord at the sacrum. In a healthy person, both branches of the ANS will function with minimum effort to maintain the body’s balance or homeostasis. If a person is subjected to stress, whether physical, emotional or environmental, the ANS will have to work harder to maintain balance. Inevitably it is the sympathetic branch that tends to dominate, as the body’s most important needs during stressful times are for energy and adrenaline to keep functioning.
This is not harmful in the short term and may even be beneficial, but if stress levels remain high for longer periods then physical and mental changes can begin to show. Because the ANS controls so many structures and functions, stress related illnesses can show themselves almost anywhere, often causing a range of seemingly unrelated signs and symptoms.
Physical Symptoms of Stress
Emotional Symptoms of Stress