1. AUTONOMIC NERVOUS SYSTEM
ARCHANA

2. Introduction
• ANS also k/a the vegetative , visceral or
involuntary nervous system, serves as the
functions of maintaining ongoing organ function
and adopting to environmental changes.
• It serves as one of component of a larger sensory
integrative motor system made up of the
nervous, endocrine and immune system that
ensures inside & outside forces affecting the
body.

4. Anatomy
• Has both peripheral and central components.
• Peripheral ANS : 3 components
• 1) sympathetic n. system (SNS)
• 2) parasympathetic system (PSNS)
• 3) enteric n. system (ENS)
• ANS efferents consist of two neurons
• i) preganglionic neurons : whose soma is in the
brain stem or sc
• ii) postganglionic : soma is in ganglion, a cluster of
neuron cell bodies outside the CNS.

6. SNS

7. PSNS

8. • The oculomotor nerve (iii) innervates the eye
• Facial and glossopharyngeal nerves innervate
face , oropharynx and salivary glands
• Vagus nerve innervates thoracic and
abdominal organs down to the descending
colon.
• Sacral parasympathetic outflow (pelvic nerves)
controls the pelvic organs.

9. ENS
• The myenteric plexus, located between the
longitudinal and circular muscle layers, is
responsible for the segmentation of gut contents
and peristalsis.
• That involves reciprocal innervation of the two
muscle layers : inhibited & other is excited with
propulsion of gut contents.
• Submucosal plexus , located between the circular
muscle and mucosa , regulates ion & water
transport across the epithelia, controls crypt cell
secretions & feeds information to regulate the
gut motility.

10. Physiology

12. Neurotransmitters and their receptors
• Based on NT release , the ANS can be divided into 3
divisions: 1) the cholinergic system
• 2) the adrenergic system
• 3) non adrenergic non cholinergic
• NANC division overlaps SNS & PSNS.
• Cholinergic fibres innervate ganglia (both SNS & PSNS) ,
PSNS postganglionic synapses, SNS postganglionic synapses
on sweat glands.
• SNS postganglionic adrenergic fibres release NE.
• Dopamine is released by SNS postganglionic adrenergic
fibres in the renal, mesenteric and coronary vascular beds
& by interneurons in sympathetic ganglia.

13. Effects on specific structures
• SNS & PSNS generally shows antagonistic effects.
• HEART: SNS activation produces +ve chronotropic
,inotropic & dromotropic effects.
• Parasympathetic activation reduces heart rate &
force.
• Blood vessels: SNS activation produces
constriction of renal, mucosal, cutaneous,
splanchnic arteries and some veins.
• PSNS activation produces opposite effects.

14. • Gut : SNS activation produces relaxation of smooth
muscle, contraction of sphincter muscle & reduced
secretions.
• PSNS effects Inc. peristalsis & secretions, relaxation
sphincter muscles.
• Lungs : SNS activation produces relaxation of smooth
muscle, bronchodilation & reduced secretions.
• PSNS produces bronchoconstriction & mucus secretion.
• Eye : SNS activation produces dilation of pupil &
retracting of nictitating membrane.
• PSNS activation causes miosis, lacrimation, contraction
of ciliary muscle, helps in accommodation of the lens
for near vision.

15. • Bladder : SNS activation produces relaxes the detrusor muscle of
bladder, contracts trigone, leads to urine retention.
• PSNS acts oppositely ,results in urine evacuates.
• Sweat gland: eccrine type glands are activated by sympathetic
cholinergic innervation.
• Apocrine glands are activated by sympathetic adrenergic
innervation.
• Sweat gland don’t receive PSNS innervation.
• Salivary glands: SNS activation produces limited saliva, decreases
blood flow.
• PSNS activation produces release of profuse saliva.
• Reproductive organs: SNS activation produces ejaculation,
contraction of muscle in epididymis, ductus deferens, prostate
glands.
• PSNS innervation is for venoconstriction in penis & clitoris,
producing erection & for mucus secretions.

16. Effect of exercise
• ANS makes compensatory changes to exercise ,
inc. SNS activity, dec. PSNS activity & stimulated
respiratory activity.
• SNS signals to the heart helps to inc. cardiac
output to meet the tissue demand.
• Max. cardiovascular changes occurring with
exercise is due to central resetting of
baroreceptor reflex, inc. sympathetic activity.
• Stimuli to chemoreceptor eliciting inc. SNS
activity include inc. in H+ , K+ , BRADYKININ.

17. EFFECTS ON AGEING
• Normal ageing in reduced in ANS function in
response to stress .
• Baroreceptor reflex function is reduced with
Inc. in age, Inc. in BP, Dec. in cardiac function,
reduced exercise tolerance.
• Vagal parasympathetic regulation of heart rate
is Dec.
• But circulating NE levels may be increased,
with reduced receptor responsivity.

18. Pharmacology
• Major classes of drugs acting on the ANS are usually
classified by the transmitter system affected.
• Alpha adrenergic agonist drugs such as phenyl
propanolamine are used to Inc. BP & treat urinary
incontinence by activating receptors on appro. Tissues.
• While its antagonists i.e. phenoxybenzamine are used
as antihypertensive agents by blocking alpha receptor.
• Beta adrenergic agonist drugs such as isoproterenol are
used as bronchodilator agents, while beta antagonists
such as metaprolol are used to treat cardiac
arrhythmias.

19. Disorders
• Trauma & diseases affecting the ANS constitute a
major portion.
• Several number of autonomic disorders exist i.e.
diabetes neuropathies, anhydrosis, sympathectomy
following cervical cord trauma, various
dysautonomias, where diffuse degeneration of SNS
& PSNS postganglionic or preganglionic neurons
occurs.

20. THANK YOU