Summary
Controls involuntary functions through sympathetic fight-or-flight and parasympathetic rest-and-digest branches.
In depth
Sympathetic: increases heart rate, dilates pupils and airways, diverts blood to muscles (noradrenaline). Parasympathetic: slows heart, stimulates digestion (acetylcholine, vagus nerve). Enteric nervous system in the gut works semi-independently.
The sympathetic system has short pre- and long post-ganglionic fibres; parasympathetic is the reverse. Most organs get dual innervation.
Key idea: sympathetic mobilises, parasympathetic conserves.
The ANS controls smooth muscle, cardiac muscle and glands. The sympathetic ganglia are near the spinal cord (short preganglionic, long postganglionic fibres), and parasympathetic ganglia are near the organs. Both use acetylcholine in ganglia (nicotinic receptors); postganglionic parasympathetic uses acetylcholine (muscarinic) and sympathetic mostly noradrenaline (adrenergic), with the adrenal medulla releasing adrenaline. Most organs have dual innervation with opposite effects, giving fine control. The enteric nervous system can operate independently.
Drugs act at these receptors: beta-blockers slow the heart, atropine blocks muscarinic receptors and dilates pupils, salbutamol relaxes bronchial muscle. Disorders include POTS and autonomic neuropathy. The hypothalamus and brainstem integrate autonomic output. Biofeedback and meditation can influence it.
Remember: parasympathetic is rest and digest, sympathetic is fight or flight.
Frequently asked questions
What is Autonomic Nervous System?
Controls involuntary functions through sympathetic fight-or-flight and parasympathetic rest-and-digest branches.
Which area of biology covers Autonomic Nervous System, and how advanced is it?
Autonomic Nervous System is one of the 54 topics in Neuroscience. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Neuropharmacology, Sensory and Motor Neurons, Brain Regions.
Can you give an example of Autonomic Nervous System?
Fear causes sweaty palms and a racing heart.
What should I learn before Autonomic Nervous System?
Autonomic Nervous System is a Beginner topic, so no earlier topic is required. Other Beginner topics in Neuroscience that pair well with it include Nervous System, Neuron, Central and Peripheral Nervous Systems.
What topics are related to Autonomic Nervous System?
The closest topics to Autonomic Nervous System are Neuropharmacology, Sensory and Motor Neurons, Brain Regions, Central and Peripheral Nervous Systems. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Autonomic Nervous System?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Autonomic Nervous System. To practise the whole of Neuroscience, use the Neuroscience quiz.
How is Autonomic Nervous System different from Neuropharmacology?
Autonomic Nervous System: Controls involuntary functions through sympathetic fight-or-flight and parasympathetic rest-and-digest branches. Neuropharmacology: Drugs act on receptors, transporters or enzymes to alter synaptic transmission. Read both side by side and note what each one explains.
How should I study Autonomic Nervous System step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Neuropharmacology and explain the difference aloud. Finally, take the Neuroscience quiz and come back to this page for any question you miss.