Autonomic nervous system:

• Structurally, the ANS consists of visceral efferent neurons (the name given to neurons of the ANS) organized into plexuses, ganglia, and nerves. It is regulated primarily by the cerebral cortex, hypothalamus, and medulla oblongata. It is generally considered to be entirely motor

• Visceral effectors include cardiac muscles, smooth muscle and glandular tissues. Afferent information from these areas goes through the dorsal root ganglia of the spinal nerves and is not a part of the autonomic nervous system

• In the somatic nervous system, an efferent neuron runs from the CNS, probably through a plexus, and to the muscle. In the ANS, there are two afferent neurons and a ganglion between them. In the SNS, the neurotransmitter used is acetylcholine. In the autonomic nervous system uses both acetylcholine and norepinephrine, or epinephrine

• A visceral efferent neuron runs from the CNS to a ganglion, sometimes to or through more than one, then to the effector. The fibers which run to the ganglia from the central nervous system are preganglionic fibers. The fibers which run from the ganglion to the effector are postgangionic fibers. The preganglionic fiber is usually myelinated, while the postgangionic is not

• A row of ganglia are found like a string of beads along the spine, called the sympathetic trunk

• The autonomic nervous system is divided into the sympathetic and parasympathetic, each using one neurotransmitter

• The preganglionic neuron bodies of the sympathetic nervous system are located in the grey matter of the spinal cord from the first thoracic nerve to the second lumbar. The preganglionic fibers of the parasympathetic nervous system are located in the midbrain, pons, medulla oblongata, and the spinal cord from the second through fourth sacral nerves

• The sympathetic nervous system generally controls fight-or-flight type responses, such as dilation of the iris', increase in heart rate, constriction of viscera or blood vessels in the skin, dilation of other blood vessels (such as those to the brain, lungs and heart), increase breathing rate, increased blood glucose levels, secretions by the adrenal glands, increased motility of the urinary organs and tissues, decreased motility of the digestive tract and constriction of sphincters, increases size and strength of heart contractions, relaxation of ducts in the gallbladder, far vision

• The parasympathetic nervous system restores and maintains order. Responses include: increased motility of the digestive tract, decreased heart and breathing rate, stimulates gastric secretions, near vision