Mediates output from the whole body except skeletal muscle
Output modulated by external and internal sensory input, often via reflexes
Reflexes: negative feedback loops within PNS and CNS
Regulates functions essential to human health and life that do not require conscious effort e.g. contraction and relaxation of vascular and visceral smooth muscle, heartbeat, metabolism, immune system
Training allows some conscious influence over some ANS reflexes
Basic organisation of the motor ANS
Regulates essential physiological functions, helping to maintain homeostasis via complementary actions of the sympathetic and parasympathetic divisions
Sympathetic ANS
‘Fight or flight’
Preganglionic neurones originate in the thoracolumbar region
Parasympathetic ANS
‘Rest and digest’
Preganglionic neurons originate in the craniosacral region
Chemical transmission in the ANS
Sympathetic division
Transmitter for preganglionic neurons - acetylcholine (ACh)
Transmitter for postganglionic neurons - noradrenaline (NA)
Parasympathetic division
Transmitter for preganglionic neurons - acetylcholine (ACh)
Transmitter for postganglionic neurons - acetylcholine (ACh)
Other transmitters
NANC transmission - does not use ACh or NA
More often, ACh/NA is co-released with a NANC co-transmitter
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