Autonomous Nervous System- Function, types & Nature

Autonomous Nervous System

• Autonomic nervous system was discovered by Langley. Autonomic nervous system (ANS) automatically regulates the activities of smooth muscles, cardiac muscles and glands.
• This co-ordination is involuntary. Autonomic nervous system usually operates without conscious control. Autonomic nervous system is entirely motor.
• All autonomic axons are efferent fibres. Autonomic nervous system is regulated by centres in brain like cerebral cortex, hypothalamus and medulla oblongata.
• Autonomic fibres release chemical transmitters at synapse. On the basis of the transmitter produced, these fibres may be classified as cholinergic or adrenergic.
• Cholinergic fibres release acetylcholine. Adrenergic fibres produce norepinephrine (noradrenaline), also called sympathetin.

Checkout more info here: peripheral nervous system divisions

Nature of Autonomous Nervous System

The autonomic nervous system regulates and co-ordinates such vital

involuntary activities like heart beat, breathing, maintenance of the composition of body fluids (= homeostasis) and body temperature, gut peristalsis, secretion of glands, etc. Autonomic nervous system consists of

two divisions –

(1) Sympathetic ANS (Thoracolumbar out flow)

1. Thoraco Lumber out flow (all thorocic + 3 lumber)
2. Preganglionic nerve small.
3. Post ganglionic nerve long.
4. Preganglionic nerve secrete acetyl choline.
5. Postganglionic nerve secrete sympathatin. (nor-epinephrine)
6. It shows sympathy (generally increase the function).
7. Expenditure of energy takes place.
8. It increase defence system of body against adverse condition.
9. It is active in stress condition, pain, fear and anger

(2) Parasympathatic ANS (Cranio-sacral out flow)

1. ANS Cranio sacral outflow (cranial-III, VII, IX, X Nerves)-(sacral-II, III, IV Nerves)
2. Preganglionic nerve long.
3. Postganglionic nerve small.
4. Secrete acetyl choline only.
5. It provide relaxation, comfort, pleasure, at the time of rest.
6. Restoration and conservation of energy takes place.
7. Collateral ganglia present in sympathetic nervous system.
8. Horner’s syndrome results from the damage of sympathetic trunk of one side.
9. A patient of Horner’s syndrome exhibits lack of sweating (on affected side), sunken eyes and constricted pupil.

Click here to know more about: reflex action and its types