Autonomic Nervous System February 2007

7/27/2019 Autonomic Nervous System February 2007

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MAIN FUNCTION

The ASN regulates body

temperature, coordinates

cardiovascular, respiratory,

digestive, and reproductive

functions. In doing so,

adjusting water, electrolytes,

nutrient, and gasses

automatically.

HOMEOSTASIS

PARASYMPATHETIC

Rest and Repose

SYMPATHETIC

Fight and Flight


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Contains afferent and efferent fibers

The effectors include:

1. Smooth muscle >< Skeletal muscle

2. Cardiac muscle

3. Glandular tissue

The ASN has a TWO Neuron System

Paeganglionic (myelinated) >< Upper Motor Neuron

Postganglionic (unmyelinated) >< Lower Motor Neuron

Slow conducting >< Fast conducting

Forming Terminal plexuses near the effector organ >< Proximal plexuses

ANATOMY


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A COMPARISON



1. Smooth muscle

2. Cardiac muscle3. Glandular tissue


Paeganglionic (myelinated)

Postganglionic (unmyelinated)

Slow conducting

Forming Terminal plexuses near theeffector organ



Skeletal muscle

The SOMATIC has TWO NeuronSystem

Upper Motor Neuron

Lower Motor Neuron

Fast conducting

Proximal plexuses (brachial,lumbosacral)

AUTONOMIC SYSTEM SOMATIC SYSTEM


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1. GENERAL SOMATIC

AFFERENT (GSA)

2. GENERAL SOMATIC

EFFERENT (GSE)

3. GENERAL VISCERAL

EFFERENT (GVE)

4. GENERAL VISCERAL

AFFERENT (GVA) (not

shown)

PHYSIOLOGY


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PHYSIOLOGY

There are TWO END Neurotransmitters

Acetylcholine Parasympathetic (conservation / restoration)

Norepinephrine Sympathetic (expenditure)

Can be Excitatory or Inhibitory >< always Excitatory (Somatic system)

There is no Trophic influence >< there is a trophic effect (Lower Motor Neuron)

Acetylcholine

Acetylcholine

Acetylcholine

NorepinephrineC

N

S

Sympathetic

Parasympathetic


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MORPHOLOGY

Parasympathetic

Hypothalamus

(Anterior)

Cranio-Sacral

Ganglia:

Cranial nerves

Intramural

Sympathetic

Hypothalamus

(Posterior)

Thoraco-Lumbar

Ganglia:

Paravertebral

Praevertebral

Cholinergic Sympathetic fibers supply:

Sweat glands, arrector pili, blood vessels,

fatty tissue of the skin.

An Exception


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Cranial

nerves:

III, VII, IX, X.

Plexuses:

Cradiac,pulmonary,

coeliac,

superior

mesenteric

Hypogastric

Accompany

arteries

Plexuses:

Cardiac,pulmonary

coeliac,

superior

mesenteric

Hypogastric

(inferior

mesenteric)

MORPHOLOGY


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Cholinergic Sympathetic

fibers supply:

Sweat glands, arrector pili,

blood vessels, fatty tissue

of the skin.


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PHYSIOLOGY

Acetylcholine

Acetylcholine

Acetylcholine

NorepinephrineC

N

S

Sympathetic(alpha, beta

receptors)

Parasympathetic

Epinephrine

Sympathetic stimulation:

-Shows extensive divergences .produce complex & coordinated

responses

- All preganglionic neurons release

ACh, but postganglionic neurons,

norepinephrine, epinephrine(adrenal medulla) or ACh (skin)

- The effect of stimulation is

prolonged & wide

Parasympathetic stimulation:

-All parasympathetic neurons arecholinergic (ACh)

- The effects are usually brief and

restricted to specific organs or sites


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STIMULATION OF SYMPATHETIC SYSTEM

1. Alertness, via stimulation of RAS

2. Euphoria feeling energetic,

disregard for danger, decrease in

pain sensitivity.

3. Increased CVS and Resp activity

--- increased BP, breathing rate

and depth.

4. Increased muscle tone ---

stimulation of extrapyramidal

system, tense even shivering.

Cellular basis:1. Release of norepinephrine on specific

locations (several seconds)

2. Adrenal medulla --- 80% epinephrine to

general circulation (several minutes)

Membrane receptors:

Alpha receptor norepinephrine

influx Ca ion contraction of

smooth muscle BP up, constriction

of GI sphincters.

Beta receptor epinephrineskeletal muscles, lungs heart, liver

indirect by second messenger

enzymes activation or inhibition

Note Beta blockers --- reduce

heart rate, relax smooth

muscles.


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STIMULATION OF PARASYMPATHETIC

SYSTEM

More localized and specific.

Postganglionic neurons intramural (ACh).

- contriction of pupils accomodation

- secretion of glands (GI)

- increased smooth muscle activity in GI

- coordination of defaecation, micturation

- reduction of heart rate and force

contraction

- sexual arousal and stimulation of sexualglands

Cellular basis:

Types of ACh receptors;

nicotinic are found on

surfaces of para &

sympathetic ganglions

excitation via ion channels.

Muscarinic are found at

cholinergic parasym.

neuroeffector junction, also at

few cholinergic symp

neuroeffector junctionsviaenzyme (longer duration).

Nicotinic & Muscarinic = chemicals that

stimulate receptors sites. Nicotinic receptors

bind nicotine. Muscarinic receptors bind

muscarine from mushrooms.


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A COMPARISON


Contains afferent and efferent fibers Contains afferent and efferent fibers


1. Smooth muscle

2. Cardiac muscle

3. Glandular tissue


Skeletal muscle


Paeganglionic (myelinated)

Postganglionic (unmyelinated)

The SOMATIC has TWO Neuron

System

Upper Motor Neuron

Lower Motor Neuron

Slow conducting Fast conducting

Forming Terminal plexuses near the

effector organ

Proximal plexuses (brachial,

lumbosacral)


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A COMPARISON


There are TWO END

Neurotransmitters

Acetylcholine Parasympathetic

(conservation / restoration)

Norepinephrine Sympathetic

(expenditure)

There is ONE END Neurotransmitter

Acetylcholine - in synapses

Can be Excitatory or Inhibitory always Excitatory (Somatic system)

There is no Trophic influence There is a Trophic effect (Lower

Motor Neuron)


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Homeostasis

The body is able to maintain relatively stable

internal conditions even though there is a

continuous change in the outside world.

Homeostasis indicates a dynamic state ofequilibrium, or a balance.

Functions of cells and organs are co-ordinated

in order to obtain homeostasis

The co-ordination is mainly accomplished by

the nervous and endocrine systems


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Valsalva manoeuvre ( expiration against a closed glottis;

bradycardia when released)

E:I ratio ( Compare R-R interval during expiration and

inspiration;about 2 in young people because heart rate isincreased during inspiration)

Tilt test for postural hypotension

Supine and standing BP ( supine BP is lower in normal

people; higher in people with autonomic neuropathy)

Postage stamp test for nocturnal erection


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THANK YOU

FOR YOUR ATTENTION

HT. SEPTEMBER 2006


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THANK YOU

FOR YOUR ATTENTION

HT. SEPTEMBER 2006


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THE SYMPATHETIC SYSTEM


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THE PARASYMPATHETIC SYSTEM


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Autonomic Nervous System February 2007

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