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).