Physiology

of
Autonomic Nervous
System

DR: AHMED M HASSAN

ASSOCIATE PROF. OF
MEDICAL
PHYSIOLOGY,SOHAG
 AUTONOMIC NRVOUS
SYSTEM

Definition : It is the system for involuntary subconscious

functions , it controls the internal environment to
maintain homeostasis .

DIVISION OF NERVOUS SYSTEM :

1- Central nervous system :
a) Brain b) Spinal cord
2- Peripheral nervous system :
a) Cranial nerves Autonomic (involuntary)
Somatic (voluntary)

b) Spinal nerves Autonomic

Somatic

1
 Somatic N .S Autonomic N .S
(voluntary) (involuntary)

1) Innervate skeletal 1) Supply smooth muscles,

muscles Cardiac and Glands

2) One neurone between 2) Has 2 neurons connected

C.N.S and effector by synapse between C.N.S &
organ organ

3) Efferent arises from 3) Efferent preganglionic

ventral horn cell. arises from lateral horn cells .

4) Chemical transmitter 4) Either acetyl cholin or

Acetyl choline norepinephrine.

2
 A.N.S differs from Somatic N.S in :-
:
In A.N.S there is :
1- Autonomic ganglia
2- Connector neurone is outside CNS
3- It regulates smooth muscles

Q: Discuss and differentiate the two

divisions of A.N.S ?

3
 A.N.S

Sympathetic Parasympathetic

1- ORIGIN: Thoraco-
Thoraco-Lumber Cranio - sacral
(Tl - T12 , LI,2
LI,2,3) 3,7,9,10 S2 , 3 , 4

1- ORIGIN: Thoraco-
Thoraco-Lumber Cranio - sacral
(Tl - T12 , LI,2
LI,2,3) 3,7,9,10
10,, s2
s2,3,4,
2-FUNCTION: Stress muscular exercise - Digestion and sleep,
fear Empting
fight micturation
flight defication

- Catabolic - Anabolic
(energy lost from the body) (energy preserved)
4- DISTRIBUTION: widspread Localised
5- DISCHARGE : as one unit (most actions) To each system
at the same time(
time separetly

4
 RELATIONSHIP BETWEEN SYMP
ATHETC AND PARASYMPATHETIC

1- RECIPROCAL : once sympathetic is

stimulated, parasympaethetic is
inhibited and vise - versa

2- COMPLEMENTAL : e.g micturation and

defication reflex. sympathetic for FILLING
and parasympathetic for EVACUATION

N.B both sympathetic and parasympathetic

together help acurate control over an
organ's activity.

5
AUTONOMIC GANGLIA

DEFINITION : It is the site of physiological

contact between pre and post
ganglionic fibers .

TYPES:
a) lateral (sympathetic)
b) collateral (mixed) or pure sympathetic
c) terminal ( parasympathetic )

Lateral ( paravertebral) 23 ganglia:

3 = cervical sympathetic chain
12 = thoracic
4 = lumber
4 = sacral

6
Collateral: Around large .B.V as:
- Caeliac ganglion
- Superior mesentric ganglion
- Inferior mesentric ganglion

Terminal (in the wall of organ, no post-

post
ganglionic as vagus or may be present
very short post-ganglionic
ganglionic fiber

7
 Pathway of pre-ganglionic
pre
sympathetic fibers:

1- May synapse in first sympathetic

chain ganglion, it enters.

2- Synapsing in other sympathetic

chain ganglia up or down.

3- Synapse in collateral ganglia.

4- Synapse in substance of adrenal

medulla itself.

8
Function :
1)) Distributing center: Sympathetic Parasympathetic

1 : 32 1:9 or 1:2 ??
2) Relay station between pre and post
ganglionic fiber

Localization : To diagnose site of relay,

by Nicotine test: (Langlay's test) painting the
ganglia with large doses of nicotine to block
the site of relay, after that if it gives no post -
ganglionic response = relay

9
Cervical Division of sympathetic
 Autonomic Nervous
System
2 divisions: •
Sympathetic –
“Fight or •
flight”
“E” division •
Exercise, –
Excitemen
t,

Emergency
, and
Embarrass
ment
Parasympathe –
tic
“Rest and •
digest”
“D” division •
Digestion, –
Defecation
, and
10
Diuresis
 DESTRIBUTION OF SYMPATHETIC
NERVOUS SYSTEM

1)) CERVICAL DIVISION:

Origin :
It arises from lateral horn cell of Ti and T2
T and
end in superior cervical ganglion
I) EYE :
a) dilatorpupilllary muscels = pupillary dilatation
= Mydriasis

b) Tarsal m.=elevation of eye lid = widening of

eye superior
inferior

c) Muller's m. = Exophthalamos = Protrusion of

eye ball in animals

d) Blood vessels of eye = V.C

e) relaxation of the ciliary muscle for vision

11
II) SALIVARY GLANDS :
a) Secretion of small amount of saliva,
rich in organic matters (enzymes)
i.e viscus saliva .
b) Squeezing around acinin of salivary
glands push saliva outside

III) SKIN :
a) Erector pilae m = erection of hairs
b) Vaso-conistriction
conistriction of blood
vessels = pallor
c) Sweat :Secretion = mental sweat.
IV) Cerebral blood vessels
= vaso-conistriction
conistriction

12
 HORNER'S SYNDROME
It Is Cerviacl Sympathectomy : characterized by :
1-PTOSIS : drop of upper eyelid .
2- MIOSIS : pupillary constriction .
3- ANHYDROSIS : dryness of skin
4-Emrophthalamos
5- Flushing of the face
ALL THESE EFFECTS ARE AT SAME SIDE OF
LESHON

13
2) CARDIQ-PULMONARY
PULMONARY DIVISION :
Segments and end in 3rd cervical and upper
4 thoracic ganglia

I) HEART : increase all cardiac prosperities as:

- positive inotropic effects = ↑ contractility
- positive chronotropic effect = ↑ Heart rate.
- = ↑ Conductivity - = ↑ Excitability
II) CORONARY BLOOD VESSELS vasodilatation
III) LUNG : a) bronco-dilatation
dilatation .
b) inhibits bronchial glands secretion of
mucous
IV) PULMONARY BLOOD VESSELS: vasoconstriction.

14
3- SPLANCHIC DIVISION:
To Abdomen and pelvis

15
16
 A) Greater Splanchic Nerve : it supplies the
abdomen e.g :
(From T5–T9, relay in caeliac ganglion)
a) wall of G.I.T → relaxation of its walls = retention ↓
motility.
b) sphincters → its contraction e.g pyloric sphincter of
stomach
c) liver → glycogenolysis = glycogen converted to
glucose .
d) adrenal medulla → release of epinephrin and nor
epinephrine .
e) spleen → contraction & release of RBCs in case of
heamorrhage
f) adipose tissues → lipolysis .
g) inhibite the intestinal juice secretion
h) relaxation of gall bladder and contraction of
its sphincter.

N.B Stimulation of greater splanchic nerve causes two

peaks rise in blood pressure :
a) First rise due to V.C of visceral blood vessel
b) Second peak due to release of catecholamin
into blood.

17
 ADRENAL MEDULLA:

Supplied by pre-ganglionic
ganglionic sympathetic
fibers (greater splanchnic nerve).

The circulating catecholamin have same

effects of direct sympathetic stimulation,
but more prolonged , So body organs
can be stimulated by 2 ways, Nervous
(direct) & Hormonal (indirect), Also
catecholamines can stimulate sites not
supplied by direct sympathetic nerves .

18
N.B adrenal meddulla is modified by
sympethetic ganglion because :

1- No post-ganglionic
ganglionic fibers

2- Causes release of 80% epinephrin. 20% nor

epinephrin.

N.B Selective secretion of adrenal medulla:

a) More epinephrine in unexpected stresses as

haemorrhaege

b) More nor-epinephrine
epinephrine in familiar stresses as
hypoxia

19
 B) Lesser splanchnic nerve:

From LI - L3, relays in inferior mesentric ganglion

It supplies the pelvis e.g-:
a) Rectum → retention of stool (+) of internal anal
sphincter
b) Urinary bladder → retention of urine by relaxation
of its wall and contraction of internal uretheral
sphincter.
c) Sex organs → ejaculation.

External genitalia:

In males : Inhibition of erection (v.c of erectile

tissue)-Ejaculation of semen
(contraction of vas deferens, prostate and
ejaculatory duct)
In females: Contraction or relaxation of female
genital organ according to the stage of menstrual
cycle and level of hormones in blood. N.B Small
splanchnic nerve (from T10
T – T12, relayes in
caeliac and superior mesentric ganglion)

20
4 -SOMATIC DIVISION :
(Orbelli phenomenon)
phenomenon

It is sympethetic supply of limbs, upper

limbs (T4- Ts) lower limbs (T10T12), both
relay in sympathetic chain = Sympethetic
stimulation delays fatigue of muscle due
to vasodilatation of skeletal blood vessels

21
 ORGANS SUPPLIED BY
SYMPATHETIC ONLY :

1- Ventricles (vagal escape).

2- Skin structures
3- Skeletal B.V.
4- Dilator pupillary muscles .
5- Adrenal medulla

22
 ORGANS SUPPLIED BY
PARASYMPATHETIC
1- Constrictor pupillary muscle .
2- Oesophagus .
3- Gastric glands .
4- Erectile tissue .
N.B Sympethe c → causes V.C of all
blood vessels, except
1. Coronaries.
2.. Skeletal blood vessels.

23
 DISTRIBUTION OF
PARASYMPATHETIC
I- CRANIAL DIVISION :
A) Oculomotor nerve ( III N ):
It arises from occulomotor nucleus ,
relays in ciliary ganglion

FUNCTION : responsible for

near visions

24
 During fixation of eyes to near
object, III nerve causes :

1)) Contrac on of ciliary muscle →

Increases convexity of the eye lens .
2)) Contraction of medical rectus
muscle → medial convergence of
both eyes together.
3)) Contraction of constrictor pupillae
muscle → papillary constric on

25
B) Fascial Nerve (VII N):
):

It arises from superior salivary nucleus, relays

in sphenopalatine ganglion.

FUNCTION : secretion of tears and saliva

which is watery, poor in enzymes and big
in amount .
C) Glossopharyngeal Nerve (IX N):
It arises from inferior salivary nucleus 9 relays
in optic ganglion .

FUNCTION : secretion of saliva

26
 D) Vagus Nerve (XN):

75%% of parasympathetic fibers of the body are the

vagus nerve. It arises from dorsal nucleus, relays
in terminal ganglia.

FUNCTION :
1- Inhibition (supression) of heart rate and
contractility.

2- Broncho-constriction
constriction and inhibition of
inspirartory center and secretion of
mucous from bronchial glands.

3- Stimulation (excitation) of G.I.T motility

and secretions . 27
EFFECT OF VAGUS NERVE
1-) ON HEART
* Inhibits all cardiac roperties, but it does not
supply the ventricles (vagus escape).
* Tonic (continuous) effect on the heart , which
is more marked in athelets.
dilaltion (V.C ) .
* Coronary vaso-constriction
constriction
2) ON LUNGS:

Mentioned before .
3) ON G.I.T:
* Evacuation of food (stimulation of G.I.T .
motility ).
* Evacuation of gall bladder.
* Stimulates secretion of: gastric juice , bile ,
pancreatic juice and mucus (Brunner's
glands)
* Increased hepatic blood flow.
N.B Vagus nerve has no post-ganglionic
post fibers
28
WHY IT'S CALLED VAGUS ?

Because it has :-

1- Afferent & efferent

2- Stimulatory & inhibitory

3- Widely distributed

29
 II- SACRAL DIVISION OF
PARAS YMPATHETIC
( nerve erigentis) It is 82 ,3,4
4 and called pelvic nerve
nd relays in hypogastric ganglia.

UNCTION :

1- It supplies urinary bladder → causes mictura on

2- distal 2/3 of large intes ne and rectum → causes
defecation
3- Male and female sex organs → erec on by
vasodilatation of blood vessels of penis (♂)
( or
clitoris (♀)
30
 MICTURATION:

Pelvic nerve causes contraction of

wall of urinary bladder and
relaxation of internal uretheral
sphincter → passage of urine

31
 DEFECATION :
pelvic nerve causes contraction of wall of
rectum and relaxation of internal anal
sphincter → passage of stool

N.B External uretheral or anal sphincters are

not under autonomic control but under
somatic control via pudendal nerve .

N.B Internal sphincter is more important than

external sphincter because it is smooth
muscle i.e fatigue resistant, while external
sphincter is skeletal muscle i.e fatigable .

32
33
 CHEMICAL
TRANSMITTERS
DEFINITION :
it is the substance which transmits the nerve
impulse from pre - synaptic to post - synaptic
membrane .

MECHANISM : Arrival of nerve impulse to

Pre-synap
synap c membrane → causes Ca+ uptake by
acetyl choline vesicles
→ causes swelling and rupture of vesicles
→ causes release of acetyle choline which can
cross the synaptic cleft
→ forma on of acetylcholin - receptor complex
→ Increase Na permeability
→ Depolarisa on Ac on poten al This Causes
Propagation
of Nerve Impulse

34
 TYPES OF NERVE ENDINGS

ADRENERGIC CHOLINERGIC
(nor adrenaline) (ac . Choline)

) Cholinergic neurotransmission :-
: ( six steps )

- Synthesis of acetyl choline :-(

: In cytoplasm)
choline + acetyl CoA CAT Ach + CoA.
( choline - acetyl - transferase)
- Storage of acetyl choline in vesicles
In the synaptic vesicles .
- Release of Acetyl choline :--
Ca++ channels in the presynaptic membrane opens
→ Ac.ch. Release by exocytosis
- Binding to receptors .
- Degradation of Ac.ch.
choline
Ac.ch. choline + acetate
esterase
- Recycling of choline
Into the neurone for resynthesis of Ac .ch.
35
SITES OF RELEASE OF ACETYL
CHOLINE
1- Autonomic ganglia (i.e all
preganglionic fibers)
2- All parasympathetic post -
ganglionic fibers .
3- Some sympathetic post -
gangljpnic as sweet glands and
blood vessels of skeletal muscles.
4- M.E.P = motor end plate
(i.e neuro - muscular junction)
5- Adrenal medulla (pre ganglionic )
6- C.N.S .
36
TYPES OF CHQLINERGIC RECEPTORS

MUSCARINIC NICOTINIC
1-This name from muscarine, a 1- Name from nicotine
substance which has a same which in small dose has the
action as ac.choline in these same action of ac.choline in
sites: a) M.E.P
B) autonomic ganglia
c) adrenal medulla
a) parasympathetic post d) C.N.S
b) sympathetic (ganglionic

2- Blocked by atropine by 2-Blocked by large dose of

comopetitive Inhibition, not nicotine (autonomic)or by
blocked by cholinestrase, so they curare ( in MEP )
have longer duration of action than
ac.choline

37
 A) Muscarinic receptors

Sites : In cardiac muscles, smooth muscle

and exocrine glands .
Subtypes : Ml , M2 , M3 3 and M4 .
-Some
Some sympathetic post-ganglionic
post as
sweet glands and blood vessels of
skeletal muscles.
- M.E.P = motor end plate (i.e neuro -
muscular junction)
- Adrenal medulla (pre ganglionic )
- C.N.S .

Ml : in autonomic ganglia, CNS and

gastric mucosa
M2 : in cardiac cells and smooth muscles
.
M3 : in smooth muscles and secretory
glands . 38

M4 and M5 : unknown sites .

 Functions of muscarinic
receptors
It has prolonged reseponse, lasts for
seconds, either exitation or inhibition :

1- Cardiac inhibition ( slow heart rate.)

2- Broncho-constriction
constriction .
3- Salivary secretion
4- Increases G.I.T secretion and motility.
5- Pupillary constriction .
6- Contraction of ciliary muscle.
7- Contraction of urinary bladder and
rectum .

39
 B) Function of Nicotinic
Receptors
It has short timed receponse only
exitatory :

1- Help ganglion transmission .

2- Secretion of epinephrine and
nor-epinephrine
epinephrine from Ad.
Medulla.
3- Stimulates N.M.J (MEP) to produce
skeletal muscle contraction

40
 FATE (REMOVAL) OF AC CHOLINE .
By choline-estrase
estrase enzyme

2 types .

True pseudo (false)

- present in nerve –endings
endings - present in plasma.
- specific only for Ac - non specific, can act on
any ester
- highly potent (strong) - less potent.

41
PARASYMPATHOMIM ETIC
DRUGS
Acts By Two Ways :

A) Direct : on tissues as muscarine,

nicotine in small dose and
carbachol.
B) Indirect : anticholinesterases as
DFP and Eserine
(war gas)

42
Anti cholinesterases : Two
types :
a) Reversible : short acting
e.g Eserine : generalized i.e. ↑
both muscarinic and nicotinic
actions. Prostigmine: Nicotinic i.e
↑ skeletal muscles MEP ac vity =
used in treatment of myasthenia
gravis .
b) Irreversible : long acting drugs
i.e toxic, called nerve gases, or
insecticides as DFP which causes
paralysis of motor func ons →
di culty in breathing → death
43
PARASYMATHOLYTIC DRUGS
Mechanism of action :
1)) Persistent depolarization
2)) Competitive inhibition as curare.
Types :
A) ganglion blockers
-Nicotine in large doses - Hexamethonium
They cause paralysis of autonomic ganglia by
persistant depolarization .
B) post - ganglionic blockers
-Atropine
C) MEP blockers
- Curare - Botulinum
- Flexidil - Succinyl cholin
. ( persistent depolarization)

44
Curare :- acts by competitive inhibition to
Ac.ch . It can be used
together with succinyl choline as muscle
relaxants
ATROPINE (anti-muscarinic
muscarinic drug ):
ACTION :
a) ON THE EYES :- Mydriasis and
cycloplegia(loss of ability for near
vision)
b) ON SALIVARY GLANDS :- : Dryness of
mouth
c) ON G.I.T :- Decrease motility =
antispasmodic
d) ON RESPIRATION : - Block secretions in
respiratory tract
e) ON C.V.S :- Tachycardia = ↑ heart rate .
f) ON URINARY TRACT :- : ↓ mo lity of
urinary bladder .

45
 Effect of injection of Ac.ch.
after Atropine on A.B.P
Nicotinic receptors in adrenal medulla
unblocked rise in A.B.P
CLINICAL USES OF ATROPINE
1- Fundus examina on → Mydriasis
2- Bronchial asthma →
Bronchodilatation .
3- Treatment of colic →↓ mo lity of
G.I.T .
4- pre anaethetic drugs to prevent
cardiac arrest.
5- Befor surgery → to block respiratory
secretions

46
 ADRENERGIC
TRANSMISSION
STEPS :

1- Phenylalanine OH Tyrosine
Dopa co2 dopamine .
2- Storage of nor epinephrine in vesicles :-
:
OH
Dopamine Nor. epinephrine
( In synaptic vesicles .)

N.B In adrenal medulla only:

CH3
Nor - epinephrine epinephrine .

3- Release of nor-epinephrine :- Into the synapse.

4- Binding by receptors : either post-synaptic

post ( on the effector
organ) or pre- synaptic receptors ( on nerve endings.)

5- Removal of nor- epinephrine ( Fate ) .

47
 SITES OF RELEASE OF
CATECHOLAMINES
1- Adrenergic endings :- only nor - adrenaline .
2- Adrenal medulla :-
causes release of :
80%% epinephrine
20%% nor-epinephrine
nor

FATE OF CATECHOLAMINES

1- Active reuptake = 80-90%

% back into ad. vesicles.

(Na-k Atpase sys.)

2- Destruction = 7 % by
MAO (oxidation)
COMT (methylation)
3- Excretion as such = 3 %

48
ADRENERGIC RECEPTORS
(ALQUISTE)

 
 
1 2 1 2

α1 : STIMULATORY
a) V.C
b) stimulation of sphincters .
α2 :- INHIBITORY 0
a) relaxation of walls of G.I.T
b) pre - synaptic inhibition of release of nor
epinephrine (-ve
ve feedback)
βl :- STIMULATORY (+)
a) heart +ve increase H.R & contraction
b) adipose tissue = lipolysis
c) renin - angiotensin . system = ↑ ABP.
β2 :-INHIBITORYO (–) relaxation of smooth muscles in :
1- bronchi = bronchodilatation .
2- blood vessels = V.D in skeletal blood vessels
& coronaries.

49
N.B β1 receptors are stimulated equally
by epinephrine and nor-epinephrine
nor
B2 receptors stimulated more by
epinephrine than N.E
α adrcnoreceptors : tow groups α 1 &
α2:
αl receptors have high affinity for
phenyl-ephrine
ephrine present on
post.synaptic
membrane of effector organ .
α2 receptors have high affinity for
clonidine. present on Pre-synaptic
Pre
nerve
endings to control release of nor-
nor
epinephrine (causes its inhibition).

N.B β2 pre-synaptic
synaptic receptors stimulate
NE release, both a 2 and β2
receptors are called pre - synoptic
receptors. 50
 RECEPTOR STIMULANTS
α Receptors stimulated by : nor - adrenaline ]-
adrenaline} isoproterenol
β Receptors stimulated by : isoproterenol J.
adrenalin]- nor - adrenaline
N.B nor - adrenaline, has a more pressor
effect because it acts mainly on α due to
receptor sensitivity.

RECEPTOR BLOCKERS :
α Blockers : ergot alkaloids .
β Blockers : inderal .(Propranolol.) N.B In G.I.T
inhibition of the
wall is by α2 and may be β2
β receptors.
While stimulation of sphincters only by al
receptors (not β1 ).
N.B α is stimulatory except on G.I.T, it is
inhibitory
While β is inhibitory except on heart, it is
stimulatory.
51
COMPARISON BETWEEN α
& β RECEPTORS

α – RECEPTOR β - RECEPTOR

1- papillary dilatation 1- far vision (ciliary muscle

2- vasoconstriction relaxation)
3- intestinal relaxation 2- vasodilatation
4- contraction of G.I.T 3- intestinal relaxation
sphincters 4- gastric wall relaxation
5- pilomotor contraction 5- increase heart rate
6- contraction of spleen 6- increase heart contractility
capsule 7- stimulation of insulin
7- inhibition of insulin secretion
secretion 8- Broncho
Broncho--dilatation.
8- contraction of internal 9- glycogenolysis .
uretheral sphincter 10-- Liplysis
10
9- salivary secretion 11-- Renin secretion.
11
10-- ejaculation
10 stimulated by:
stimulated by : Isoproterenol, adrenaline ,
N.E , epinephrine and N.adrenalin
phenyl -ephrine Blocked by :
Blocked by: Propranolol.
Ergot alkaloids
52
 MECHANISM OF ACTION OF
ADRENERGIC RECEPTORS

αl Increases intra-cellular
cellular C-AMP.
C

α2 Inhibit adenyl cyclase enzyme, so it

decreases cyclic AMP so interfering
between the combination between
the transmitter and its receptor

βl receptors stimulates adenyl cyclase ,

increases cyclic AMP

β2 receptors → unknown mechanism

but may also act by increasing C-AMP
C

53
 Sympathomimetic drugs
(adrenergic Agonists )
Mechanism Of Action:
1- stimulate release of catecholamines
e.g Tyramine, Amphetamine
↓
(indirect acting agonist )
2- inhibit reuptake e.g Cocaine
3- α stimulants
Direct acting agonist e.g adrenalin,
NE
4- Ganglion stimulants : Nicotine in small
dose.

54
 SYMPATHOLYTIC DRUGS

1- Inhibit synthesis ( alpha methyl

tyrosin) and storage e.g
reserpine .
2- Inhibit release of catecholamines
e.g guanithidine .
3- Recepor blockers a & B
receptors
4- False transmiters e.g a methyl
dopa ( aldomet ).
5- Ganglion blockers e.g
hexamethonium and arfonad

55
 DIFFERENCE BETWEEN

EPINEPHRIN NOR -
EPINEPHRE
1- sites of release - adrenal medulla adrenal medulla &
2- receptor - α and β equal adrenergic nerve
sensetivity - increase cardiac ending
3- on heart output and heart - mainly a & β
4- pressor effect rate slightly
(peripheral - decrease - decrease both
resistance) - increase
5- metabolic -glycogenolysis, - no effect
6- systolic pressure lipolysis - little effect
7- diastolic - increase - increase
pressure - decrease - increase
8- G.I.T motility - decrease - decrease

56
 PHEOCHROMOCYTOMA

Tumour of adrenal medulla resulting in

attacks of hypertension in emergency states,
discharge of sympathetic leading to:

1- increased arterial pressure

2- increased blood flow to active muscles
3- increased blood glucose level
4- increased rate of blood coagulation .
5- increased mental activity
6- increased glycogenolysis in liver and
muscles.
7- increased rate of cellular metabolism.

56
Control of A.N.S by Higher
centers
1- Some autonomic reflexes as
micturation, defecation and
erection are under inhibitory
control of centers in C.N.S .
2- Cardio-vascular,
vascular, respiratory and
digestive activity are under
control of medulla within the
brain stem.
3- Stimulation of anterior nucleus of
hypothalamus is accompanied by
parasympathetic effects, while
stimulation of posterior nucleus is
accompanied by sympathetic
effects.
57
1- Cardiovascular autonomic reflexes :
High arterial pressure → baro-receptors
baro →
pressure fall back toward normal.
2- Gastrointestinal autonomic reflexes :
a) Un-conditioned
conditioned reflex e.g. presence of
food in mouth causing salivary secretion .
b) Defecation reflex.
c) Micturation reflex.
d) Sexual reflexes : Erection
(parasympathetic function, followed
by ejaculation (sympathetic function)

N.B biofeedback research demonstrate that

the A.N.S is not autonomic, it can be
voluntary.

58
 DISORDERS OF AUTONOMIC
FUNCTIONS

SYMPATHETIC QVERACTIVITY:

1- HYPERTENSION : sympathetic
increases peripheral resistance
2- ANGINA PECTORIS : sympathetic
increases myocardial O2
3- Hyperthyroidism: Thyroid hormone
increases sensitivity or number of
adrenergic receptors

59
 GENERALISED AUTONOMIC
INSUFFICIENCY

1- Male impotence (no erection)

2- Anhydrosis
3- Orthostatic hypotention .
3- No pupillary control
4- Urinary retention .

N.B all these may accompany diabetes

mellitus

THE ENTERIC SYSTEM:--

Neural plexuses within walls of the
oesophagus , stomach small intestine and
colon , Functioning independent of A.N.S so
sympathetic and parasympathetic
innervation alters the intrinsic activity of the
enteric neural network .

60
 MCQs

1- Concerning the ANS: •

A- Supplies voluntary •
organs.
B- Supplies involuntary •
organs.
C- Is a part of somatic •
nervous system
D- Have one neuron. •
 con
2- In Horner syndrome •
all are correct except:
A- The upper eye lid is •
elevated.
B- The skin is dry and •
red.
C- Miosis. •
D- Enophthalmous •
 con
3- Sympathetic nervous •
stimulation produces:
A- relaxation of the internal •
urethral sphincter.
B- decreased stomach secretion •
and motility.
C- constriction of the pupil. •
D- decreased heart rate