3.ANS and their side effect and important

11/23/2024 1
Autonomic nervous system

11/23/2024 2
Autonomic nervous system
¨ The term ‘autonomic’ is derived from the words
• Auto  self and
• Nomos  control
¨ Controls functions of the involuntary organs of the body that
include:-
 Heart and blood vessels
 Exocrine and endocrine glands
 All visceral organs

11/23/2024 5
SOMATIC & AUTONOMIC FIBERS/NEURONS
SOMATIC NERVOUS SYSTEM
It only takes one motor neuron to reach its target/effector
organ
Origin: anterior horn of the spinal cord
Target: skeletal muscles
 At the synaptic level, the neuron releases acetylcholine,
which binds to the nicotinic receptors on muscles to
stimulate contraction.

11/23/2024 6
SOMATIC & AUTONOMIC FIBERS/NEURONS…
AUTONOMIC NERVOUS SYSTEM
 It takes two motor neurons to reach its target/effector organ
(i) Pre-ganglionic neuron
 Origin: brainstem/spinal cord
 Target: synapses with a ganglion
(ii) Post-ganglionic neuron
 Origin: ganglion
 Target: effector organ (e.g., viscera...)

11/23/2024 10
Sympathetic Nervous System(SNS)
“Fight, Flight, or Fright stage”
 Activated in stressful situations
 Location: Spinal Cord, T1 – L2 (thoracolumbar)
Action potentials/signals from the SNS pass
through this thoracolumbar outflow.

11/23/2024 11
Sympathetic Division

11/23/2024 12
GANGLIONIC NEURONS/FIBERS
Sympathetic Nervous System
Pathway:
(i) Short pre-ganglionic neurons

11/23/2024 13
GANGLIONIC NEURONS/FIBERS…
(ii) Long post-ganglionic neurons
 Adrenergic fibers - release norepinephrine at
the synaptic junction

11/23/2024 14
SYMPATHETIC NERVOUS SYSTEM…
CHAIN/PARAVERTEBRAL GANGLIA
 Sympathetic fibers from the upper thoracic spinal cord
extend to the cervical region to synapse with the
cervical ganglia:
o Superior cervical ganglia
o Middle cervical ganglia
o Inferior cervical ganglia
o Stellate ganglia
 These cervical ganglia provide sympathetic efferent
innervation to the face and head.

11/23/2024 15
SYMPATHETIC NERVOUS SYSTEM…
A.SUPERIOR CERVICAL GANGLIA
• Pathway of Pre-ganglionic Fibers: Sympathetic fibers from T1-
T3 pass through the chain ganglia then extend superiorly to
synapse with the superior cervical ganglia
 Pathway of Post-ganglionic Fibers:
o Join/Contribute to spinal nerves to supply:
 Arrector pili
 Blood vessels
 Sudoriferous sweat glands
 Contribute branches to the heart, lungs, and
esophagus
 Form carotid plexus

11/23/2024 16
SUPERIOR CERVICAL GANGLIA…
¨ The carotid plexus branches into three to
innervate:
1. Dilator pupillae
2. Ciliary muscle (ciliaris)-- Contracts to make the
lens flat (accommodation)
3. Salivary glands
• Decreasing salivary output
• Increases mucin
4. Lacrimal glands

11/23/2024 17
B. Middle And Inferior Cervical Ganglia
 Fibers from T1-T3 can contribute to the plexuses
 Fibers from T1-T5 can exit on their own as
splanchnic nerves
Cardiac plexus
Esophageal plexus
 Pulmonary plexus

11/23/2024 18
PREVERTEBRAL/COLLATERAL GANGLIA
Divert blood flow away from the digestive and
excretory organs to the brain and muscles.
Sympathetic fibers from T5-T9 pass through the chain
ganglia and exit as the greater splanchnic nerve
o The greater splanchnic nerve synapses with the
celiac ganglia

11/23/2024 19
PREVERTEBRAL/COLLATERAL GANGLIA…
• Pathway of Post-ganglionic Fibers:
o The post-ganglionic fibers branch out to innervate
some abdominal organs
Stomach
Liver
Gall Bladder
Pancreas
Spleen
Duodenum

11/23/2024 20
B.SUPERIOR MESENTERIC GANGLIA
• Sympathetic fibers From T5-T9 pass through the chain ganglia and
exit as the greater splanchnic nerve(GSN)
o The GSN synapses with the celiac ganglia AND the superior
mesenteric ganglia
 The superior mesenteric artery supplies the duodenum (distal half),
jejunum, ileum, cecum ,ascending colon, and transverse colon
(proximal, 2/3s)
 Inhibit the digestive process by:
 Decreasing peristalsis
 Decreasing absorption (through vasoconstriction)
 Decreasing secretion

11/23/2024 21
C. ADRENAL MEDULLA
• Pathway of Pre-ganglionic Fibers: The greater
splanchnic nerve synapses with the chromaffin cells of
the adrenal medulla
o Example of an intramural ganglion
o Exception to the usual two-neuron structure of the
sympathetic nervous system
• Pathway of Post-ganglionic Fibers
o The chromaffin cells release norepinephrine and
epinephrine to the general circulation, causing a
diffuse, systemic effect

11/23/2024 22
D.AORTICORENAL GANGLIA
o Sympathetic fibers from T10-T11 pass through the chain
ganglia and exit as the lesser splanchnic nerve.
o The lesser splanchnic nerve synapses with the aorticorenal
ganglia.
o The post-ganglionic fibers innervate the kidney and
ureter
 Decrease urine production (by decreasing blood
flow to the kidneys)
 JGC release renin, which triggers the angiotensin II cascade to
increases blood pressure

11/23/2024 23
E.RENAL PLEXUS
• Pre-ganglionic Fibers: Sympathetic fibers from T12
pass through the chain ganglia and synapse with diffuse
ganglion cells (renal plexus)
• Post-ganglionic Fibers: The post-ganglionic fibers enter
the kidney to:
o Support the aorticorenal ganglion fibers in decreasing
urine production in the kidney.
o Decrease peristalsis of the ureter

11/23/2024 24
F.INFERIOR MESENTERIC GANGLION
• Pathway of Pre-ganglionic Fibers:
o Sympathetic fibers from L1-L2 (sometimes L3) pass
through the chain ganglia and exit as lumbar
splanchnic nerves
o The lumbar splanchnic nerves innervate the inferior
mesenteric ganglion
Pathway of Post-ganglionic Fibers:
 The inferior mesenteric artery supplies the transverse
colon (distal 1/3), descending colon, sigmoid colon,
and upper rectum---decrease peristalsis and
defecation

11/23/2024 25
G. SUPERIOR HYPOGASTRIC PLEXUS
 Sympathetic fibers from T12-L2 (sometimes L3) pass
through the chain
ganglia and synapse with the superior hypogastric
plexus.
 The postganglionic fibers go to the internal urethral
sphincter(-1AR) and detrusor (-2 and -3
receptor)

11/23/2024 26
H. INFERIOR HYPOGASTRIC PLEXUS
o Sympathetic fibers from T10-L2 pass through the
chain ganglia and exit around the sacral region as the
sacral splanchnic nerves
o The sacral splanchnic nerves synapse with the
inferior hypogastric plexus
• The postganglionic fibers of this plexus innervate
the gonads

11/23/2024 27
INFERIOR HYPOGASTRIC PLEXUS…
1. Males
 The postganglionic fibers of the inferior hypogastric
plexus innervate the penis and scrotum
o Initiate ejaculation
o Stimulate prostate gland to produce seminal fluid
2. Females
 The postganglionic fibers innervate the uterus and
vagina.

11/23/2024 28
Fig. Structure of the sympathetic division of the autonomic nervous system

11/23/2024 29
Parasympathetic Nervous System(PSNS)
✹“Rest and Digest stage”
✹ Location: Brainstem (CN III, VII, IX, X) and
Spinal Cord, S2-S4 (craniosacral)
✹ Action potentials/signals from the PSNS pass
through this craniosacral outflow

11/23/2024 30
Parasympathetic Division

11/23/2024 31
FIG. Sympathetic (thoracolumbar outflow) and parasympathetic
(craniosacral outflow) systems.

11/23/2024 32
GANGLIONIC NEURONS/FIBERS of PSNS

11/23/2024 33
OCCULOMOTOR NERVE - CN III
• Long preganglionic PS fibers outwards to ciliary ganglion
postganglionic fibers
pierce through sclera and into the ciliary muscle.
Action:
1. Ciliaris muscles contract zonules become relax
lens becomes globular (accommodation) produces near
vision
2. Sphincter pupillae  constricts  near vision
(less light rays come to eye)

11/23/2024 34
FACIAL NERVE – CN VII
¨ Super Salvitory Nucleus long preganglionic axons 
synapses to two ganglions:
¨ 1. pterygopalatine ganglion Postganglionic fibers
stimulates glandular structures like lacrimal, nasal and
palatine glands
2. submandibular ganglion  Postganglionic
stimulate glandular structures like submandibular and
sublingual glands
 ↑↑ production of saliva (↑↑ Amylase – to break down
carbohydrates)

11/23/2024 35
GLOSSOPHARYNGEAL NERVE - CN IX
• Long preganglionic axons from Inferior Salvitory
Nucleus  synapse with otic ganglionPost ganglionic
fibers innervate the parotid salivary gland
Action:
• ↑↑ Salivary amylase secretion which breaks down
carbohydrates.
• Watery secretions helps turn food to bolus to help with
deglutition.

11/23/2024 36
VAGUS NERVE – CN X
Dorsal Nucleus of Vaguslong preganglionic axons
 synapse with:
1. Pulmonary Plexus Lungs
2. Cardiac Plexus  Heart
3. Esophageal Plexus  Stomach
4. Submucosal & Myenteric PlexusIntestines
5. Celiac Plexus  Kidney & Intestines
6. Hepatic Plexus Liver & Gall Bladder

11/23/2024 40
ANS Receptors
I) ADRENERGIC RECEPTORS
• Sensitive to epinephrine (adrenaline) and
norepinephrine
• Two classes:
o α adrenergic receptors
α1, α2
o β adrenergic receptors
β1, β2, β3

11/23/2024 41
Table 1. Different adrenergic receptors and their intracellular signaling

11/23/2024 42
TARGETS AND LOCATIONS OF ADRENERGIC
RECEPTORS
A. VASCULAR SYSTEM
 Adrenergic receptors are located in the tunica media of
the blood vessels
o Very sensitive to Epi or NE in controlling the diameter
of the blood vessels.
 Vascular system usually contains either α1 or β2
adrenergic receptors:-
o α1: causes constriction of the blood vessels
o β2: causes dilation of the blood vessels

11/23/2024 43
TARGETS AND LOCATIONS OF ADRENERGIC
RECEPTORS…
1. Blood Flow to the Integumentary System
Vascular smooth muscles of the skin contain α1
adrenergic receptors.
o ↓Blood flow to the skin → palish skin appearance
o Arrector pili muscle contracts → hair stands up

11/23/2024 44
Blood Flow to the Kidneys
• Blood vessels to the kidneys have α1 receptors →
blood flow blood filtered
↓ → ↓ → urine
↓
Blood Flow to the GIT
• Splanchnic circulation has α1 adrenergic
receptors blood flow digestion,
→ ↓ → ↓
absorption and secretions.

11/23/2024 46
Blood Flow to the Skeletal Muscles
Vascular smooth muscles of the skeletal muscles contain
β2 adrenergic receptors
o Dilate the blood vessels blood flow
→ ↑ → ↑perfusion to
the muscles
Blood Flow to the Heart
 Under metabolic control
 The ANS DOES NOT have a significant effect on the
coronary circulation

11/23/2024 47
Blood Flow to the CNS
• The blood flow of the CNS is NOT dependent on the
autonomic nervous system
• Therefore, vascular system to the CNS contains α1 and
β2 adrenergic receptors.
 Myogenic mechanism
The dilation or constriction of the blood vessels
depends on BP
 ↑BP = constriction
 ↓BP = dilation

11/23/2024 48
B. EYES
(1) Ciliaris Muscle
• Contains β2 adrenergic receptors
• Ciliaris muscles relax → ciliary zonules tighten → lens
flatten → far vision
(2) Dilator Pupillae
• Contains α1 adrenergic receptors
• Contraction of dilator pupillae → pupil dilation → ↑light
rays hitting the retina → far vision

11/23/2024 50
(C) SALIVARY GLAND
• Contains β2 adrenergic receptors
o Switches salivary secretions into making
↓Water and electrolyte-rich saliva
↑Mucin proteins
↑Different salivary enzymes
End result: thicker saliva

11/23/2024 51
Fig. Adrenergic receptors on the salivary gland.

11/23/2024 52
D. HEART
 SA node, AV node, Bundle of His and the
contractile myocardium contains β1 adrenergic
receptors.
o ↑APs→ ↑HR → ↑CO → ↑BP
o ↑Ca2+ loading → ↑contractility → ↑SV →
↑CO → ↑BP

11/23/2024 53
KIDNEYS, URETER AND URINARY BLADDER

11/23/2024 54
PANCREAS
¨ Both the α and β cells of
the pancrease have α2 ARs
α Cells
• Stimulate release of
glucagon from the α cells
β Cells
• ↑K+efflux keeps β cells
→
from being stimulated →
inhibit insulin release

11/23/2024 56
RESPIRATORY SYSTEM
(1) Bronchial Smooth Muscles
• Contain β2 ARs
o Stimulate relaxation of the smooth
muscles bronchial diameter
→ ↑ →
ventilation perfusion
↑ → ↑ →
blood O2
↑
(2) Mast Cells
• Contain β2 ARs
o Inhibit release of histamines →
bronchial arteries constrict blood
→ ↓
flow secretions in seromucous
→ ↓
glands open patent airway
→ →
ventilation
↑

11/23/2024 57
CHOLINERGIC RECEPTORS
¨ Are mainly specific for the PSNS.
¨ Respond to acetylcholine (ACh) release at the
preganglionic and postganglionic fibers.
o Nicotinic Receptors
o Muscarinic Receptors
 All preganglionic neurons are cholinergic and release
ACh, which interacts at nicotinic receptors on the
postganglionic neurons.
 Most postganglionic neurons of the parasympathetic
division are also cholinergic.

11/23/2024 58
CHOLINERGIC RECEPTORS…
 Receptors for ACh in the effector organs are
muscarinic receptors rather than nicotinic
receptors.
o Ach released from preganglionic neurons of the
PS division activates nicotinic receptors.
o ACh released from postganglionic neurons of the
PS division activates muscarinic receptors.

11/23/2024 59
Nicotinic Receptors
• Respond to ACh and nicotine (an Ach agonist).
• They are ligand gated ion channels.
• Types:
o Nn found in autonomic ganglia & CNS.
o Nm  located in NMJ , specific to skeletal
muscles.

11/23/2024 60
Muscarinic receptors
G-protein coupled receptors or serpentine
receptors.
o M1
o M2
o M3
o M4
o M5

11/23/2024 61
MECHANISM OF ACTION OF NICOTINIC
RECEPTORS
ACTION IN THE PARASYMPATHETIC SYSTEM (NN)
• Presynaptic neurons released ACh and bind
onto the post synaptic neuron ion channels 
Na ion channel opens Na+ floods into the
post synaptic neuron to excite the neuron

11/23/2024 62
MOA OF NICOTINIC RECEPTORS…

11/23/2024 63
MOA OF NICOTINIC RECEPTORS…
ACTION IN THE SOMATIC NERVOUS SYSTEM (NM)
• Nicotinic receptors at the neuromuscular
junction (Nm) have delta, alpha, gamma
chains

11/23/2024 64
MUSCARINIC RECEPTORS
 Muscarinic receptors either stimulate or inhibit the target
organs.
o M1 (+)
o M2 (-)
o M3 (+)
o M4 (-)
o M5 (+)
 (+)  stimulates the organ, Gq coupled receptor.
 (-)  inhibits the organ, Gi coupled receptor.

11/23/2024 65
LOCATION OF MUSCARINIC RECEPTORS
M1
Found in the:
o CNS (play a role in cognition like M4-M5)
o Gastric glands (especially the parietal cells)
• M3 receptors can be found here too.

11/23/2024 66
LOCATION OF MUSCARINIC RECEPTORS…
M2

11/23/2024 67
M3

11/23/2024 68
M4-M5
Only found in CNS
Plays a role in memory, arousal and
analgesia (cognitive function).

11/23/2024 69
Table 2. Summary of Muscarinic Receptors

11/23/2024 70
Functions of the Sympathetic NS
1) Largely fight or flight response.
2) Works with adrenal medulla (epinephrine).
3) Increases metabolic rates & cardiac out put during
exercise & excitements.
4) Generally excitatory to almost all body parts except
for the GIT (inhibitory).
 Visualizing body changes that occur during “E
situations” (exercise, emergency, excitement,
embarrassment) will help you remember most of
the sympathetic responses.

11/23/2024 71
Function of Parasympathetic NS
1) Regulation of digestion, defecation &
micturition.
2) Conservation of energy (anabolic).
3) Maintains a homeostatic environment
"resting & digesting" system.
4) Parasympathetic neurons in general have
inhibitory effect on almost all body tissues
except in the GIT (excitatory effects on GIT).

11/23/2024 72
Function of Parasympathetic NS…
• The acronym SLUDD can be helpful in
remembering 5 parasympathetic increasing
responses.
– salivation (S), lacrimation (L), urination (U),
digestion (D) and defecation (D).
• Besides the increasing SLUDD responses, other
important parasympathetic responses are “three
decreases”:
– Decreased heart rate, diameter of airways &
diameter (constriction) of the pupils.

3.ANS and their side effect and important

More Related Content

Similar to 3.ANS and their side effect and important

More from MikaPop

Recently uploaded

3.ANS and their side effect and important