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The autonomic nervous system is made up of the ''Sympathetic Nervous System'' (SNS) and the ''Parasympathetic Nervous System'' (PNS). The SNS is activated during critical situations, such as fight or flight responses whilst the PNS is activated whilst at rest, such as during food digestion after eating.

The autonomic nervous system is made up of the ''Sympathetic Nervous System'' (SNS) and the ''Parasympathetic Nervous System'' (PNS). The SNS is activated during critical situations, such as fight or flight responses whilst the PNS is activated whilst at rest, such as during food digestion after eating.

==Autonomic Nervous System: Basic Principles==

==Basic Principles==

Within the somatic nervous system, the link between the skeletal muscle cell and the central nervous system consists of a single nerve fibre. Within the ANS, efferent signals are transmitted by two neurons between the CNS and the effector cells. The first neuron is a '''preganglionic neuron''' with a cell body in the CNS (either brain stem or spinal cord). The second neuron is '''postganglionic''' and connects the effector cell with the ''autonomic ganglia'' found outside the CNS. The ANS nerve fibres are generally composed of ''General Visceral Motor'' (GVM) that transmit purely motor signals and ''General Visceral Sensory'' (GVS) which transmits purely sensory information.   

Within the somatic nervous system, the link between the skeletal muscle cell and the central nervous system consists of a single nerve fibre. Within the ANS, efferent signals are transmitted by two neurons between the CNS and the effector cells. The first neuron is a '''preganglionic neuron''' with a cell body in the CNS (either brain stem or spinal cord). The second neuron is '''postganglionic''' and connects the effector cell with the ''autonomic ganglia'' found outside the CNS. The ANS nerve fibres are generally composed of ''General Visceral Motor'' (GVM) that transmit purely motor signals and ''General Visceral Sensory'' (GVS) which transmits purely sensory information.   

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