Autonomic Nervous System (ANS)

"if all consciousness was eliminated, vital physiological processes would continue virtually unchanged. Deeper states of unconsciousness are not necessarily more dangerous, as long as nourishment is provided... Survival under these conditions is possible because routine adjustments in physiological sustems are made by the ANS oustide our conscious awareness."

... ANS regulates: body temperature; coordinates cardiovascular, respiratory, digestive, excretory, reproductive functions. It adjusts water, electrolyte, nutrient, and disolved-gas concentrations in body fluids.

Opposed to the Somatic Nervous System (SNS), that extends from the Central Nervous System, contacts and exerts direct control over the skeletal muscles.

Motor control

ANS- [the afferent sensory information of the ANS is processed in the CNS, and then the efferent impulses are sent to effector organs-- such as smooth muscles, cardiac muscle and glands] .

At least 2 neurons are involved in the pathways, one always in the periphery; Motor control involves- Preganglionic neuron- which send axons to synapse on ganlionic neurons whose cell bodies are outside the CNS.

So, the receptor and effector organ locations differ from the SNS. The arrangement of the neurons connecting to the CNS also differs.

Sympathetic- fight or flight. Preganglionic fibers in the thoracic and upper lumbar segments synapse. Stimulates tissure metabolism, increases alertness, prepares the the body to deal with emergencies.

Parasympathetic or Craniosacral division- preganglionic fibers originating in either the brain stem (Cranial nerves: 3, 7, 9, 10) or the sacral spinal cord. Rest and Repose. conserves energy, and promote digestion.

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