Heba al- hyasat

…

10

Mohd.Khatatbeh

Sanaa halabiah

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: (ANS) system nervous Autonomic

BEFOR WE START ! what is the autonomic system ? ( just to understand !)

Now !

Autonomic nervous system (ANS)

Is the part of the nervous system that regulates activities of internal organs which

import the adaptation of the body for internal and external changes , this system also

improve the control of homeostasis .

nervous system

peripheral nervous system

autonomic nervous system

sympathetic nervous system

parasympathetic nervous system

somatic nervous system

central nervous system

brain and spinal cord

Our nervous system divided into :

- Central , consists of brain and spinal cord .

- Peripheral , consists of every thing else .

The Peripheral nervous system divide into sensory division and motor

division which divide into : ( somatic system and autonomic system) ..

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This system has two division :

Autonomic

system

(ANS)

Parasympathetic (PSNS)

(rest and digest)

The origin is the brain and

sacral region

“craniosacral”

Sympathetic (SNS)

(fight or flight)

The origin is the thoracic

and lumbar region

“thoracolumbar”

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**In situation that require alertness and energy such as facing danger or doing physical

, to mobilize the body for action sympathetic divisionactivities , the ANS activates its

ex. When you walking in the forest , and then you facing a dangerous object like big

bear you will either to fight or flight (run) and in both situation you need the activity of

: we are needing a group of reaction that takes part in our body, muscles so

On the other hand during ordinary situation the parasympathetic division conserves

and restores , it :

- Slow heartbeat

- Decreases respiratory rate

- Stimulates digestion

- Removes waste

- Store energy

- Increases cardiac output

- Accelerates respiratory rate

- Releases stored energy and

dilates pupils

- Inhibits body processes that

are less important in

emergencies such as

digestion and urination

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1. Sympathetic (fight or flight)

Example of adaptation to external stimuli ( Fight and Flight Reaction )

Increase heart rate and force of contraction , to pump more blood which deliver

to our tissue and cell and also by increasing the force of contraction at your heart.

Widely dilated pupils , you have trying to see the hole details of the dangerous

object .. to take butter decision in this case .

Pallor (pale of fear) as blood is directed to the skeletal muscle , discoloration of

the skin because we have reducing the blood flow to our skin and unnecessary

tissue but we have needing more blood flow to our muscle tissue.

Goose pimples , when the hair stand on head and skin this actually happened

because of the contraction of the smooth muscle cell in the base of the hair

follicle.

Cold sweat , because of the low amount of blood in skin

Dry mouth , by reducing salivating or inactivation salivary gland (we have in our

mouth salivary glands) .

Actually , reducing the activity of all the endocrine system ( except of sweat glands)

**Ganglions : they are cluster of cell body of neuron ( nerve cell cluster)

The axon from the origin until the

effective structure composed of two

neurons :

1. First neuron come from the

spinal cord (the cell body

located in the spinal cord )

2. Second neuron innervated the

functional organ of our body

And we have synapses of 1st neurons

with 2nd neurons , located at the

chain of ganglion.

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First neuron come from spinal cord and we called it paravertebral ganglion (we have

two of them , one on each side of the spinal cord ) while we called the second neuron

prevertebral ganglia .

* paravertebral ganglia: present near the vertebral column.

* prevertebral ganglia: present apart from the vertebral column near the organs.

At that chain of the ganglia we have synapses of the 1st neuron with the 2nd neuron .

The fiber of the first neuron called preganglionic fibers , and the second called

postganglionic fibers .

**We can found some terminal

solitary (not paired) ganglion inside

abdominal cavity , simply we have

three ganglion and we called them

prevertebral ganglia ( present apart

from the vertebral column near the

organs ) , they called :

- celiac ganglion.

- superior mesenteric ganglion.

- inferior mesenteric ganglion.

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2. Parasympathetic (rest and digest)

Some difference between SNS and PSNS :

- In both , from the origin we have cell body, long axon tour and synapses , but we

don’t have specific ganglion for the parasympathetic system while we have in

sympathetic .

- We have short preganglionic in sympathetic (SNS) while long one in

parasympathetic (PSNS) .

- We have long postganglionic fiber in sympathetic (SNS) while short one in

parasympathetic (PSNS).

- ** remember that the origin is another different between them .

This represent ganglion where we have the synapses between the postganglionic and

preganglionic neurons (in autonomic ) so the cell bodies located in ganglion which

different from the somatic system .

The somatic system is having cell body at the level of spinal cord (like the motor

neuron), long axon tour effector structure and the synapse between the terminal of

somatic neuron and effected structure .

We don’t have ganglion along the somatic nerve system but we have along automatic .

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# convergence and divergence in Sympathetic division :

- Convergence : have many presynaptic neurons synapsing with one neural.

- Divergence : presynaptic neuron terminals synapsing with many post synaptic

neurons .

** the responses to parasympathetic stimulation are localized responses while to

sympathetic are more generalize responses ..

This because of the origination of the fiber , we have more divergence and convergence

in the sympathetic system which are depend more diffuse in the responsible

stimulation , while for the parasympathetic stimulation you have more drifted

responses and related to organ themselves .

The axon is not have only one

terminal , they can have many

terminal some of these are signifies

with the neuros at the same

significant level and some terminal

are going up from the neuron either

upper significant level or lower

significant level .

This neuron can have some neurons

from this significant level so we

have a lot of convergence while in

parasympathetic you have long

axon tour .

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Ex. When the food retching to the small intestines, you are getting more activity in the

small intestines and reducing the activity in the stomach , so we have limited

responsible to parasympathetic system .

Physiological characteristics of Automatic nervous system : (ANS)

High speed of onset , when you facing a danger object you don’t wait your body

to start their reaction immediately , the reaction is prepare your body for the

new situation .

Automatic nature , for example we can’t control of our heartbeat so, its

automatic .

Tonic activity , that means we haven’t zero activity in any time but the level of

activity can increase or decrease , so we have certain level for (PSNS) and (SNS) .

Adrenal gland is exception :

* The doctor did not discuss this topic

• Synapse in gland

• Can cause body-wide release of

epinephrine

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Effects of sympathetic stimulation :

** we have some tissue in our body which are widely distributed tissue such as ( vessels

and sweat glands ) .

These widely distributed tissues are need a systemic which can diffuse effect . these

structure innervation only by sympathetic system , we don’t have parasympathetic

control over these function structure .

Blood pressure , There are many things involved in regulating blood pressure

( vessels , hormones, function of the heart itself and the body fluid )

We’ll focus on diameter of vessels …

Sympathetic is the major in the control of the diameter of vessels by cause of

vessels friction which lead to decrease of blood pressure , so the tissue are widely

distributed tissue .

Body temperature , by the sympathetic effects on cutaneous blood vessels and

sweat glands.

Cardiovascular system , effects on vessels will result in redistribution of blood by

enhancing blood flow to skeletal muscle and reducing blood flow to skin and

mesentery.

Effects on heart , by increasing heart rate , causing more powerful contraction

(increasing the force of contraction ) which lead to more blood distributed to our

tissue , more oxidation of these tissues and increasing “cardiac output” : is the

amount that can be measured ( volume of blood pumped per minute) ..

Respiratory system , causes relaxation of bronchial muscle which result in

bronchodilation , getting more oxygen to the smooth muscles ..we needing more

air flow .

Digestive system , inhibition of motility and secretion, one of the aspect is dry

mouth .

Metabolic effects , metabolic simply is break down of glycogen to more glucose

become available in body fluid , by (SNS) : mobilization of glucose , Increased

lipolysis and Increased metabolic rate .

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Effects of parasympathetic stimulation :

Gastrointestinal system , increases motility and secretory activity.

Glands , increases secretory activity (but remember sweat glands are under

sympathetic control).

Heart , decrease rate of contraction (bradycardia).

At conductive tissue !

We have slow depolarization contraction potential by increasing

parasympathetic stimulation , the rate of slow depolarization become more slow

, so in this case the number of action potential generation per minute will be less

in this by the parasympathetic stimulation.

While by sympathetic stimulation we have increasing the rate of slow

depolarization and we got more frequent generation of action potential.

Pupil , control pupil diameter by papillary light reflex

(miosis) → (regulates the amount of light falling on retina).

Accommodation of the lens for near vision.

Voiding the urinary bladder (micturition).