Download 16-2 The Sympathetic Division

Chapter 16
The Autonomic Nervous
System and
Higher-Order Functions
Lecture Presentation by
Lee Ann Frederick
University of Texas at Arlington
© 2015 Pearson Education, Inc.
An Introduction to the ANS and HigherOrder Functions
• Learning Outcomes
• 16-1 Compare the organization of the autonomic
nervous system with that of the somatic
nervous system.
• 16-2 Describe the structures and functions of
the sympathetic and parasympathetic division of
the autonomic nervous system.
• 16-3 Describe the mechanisms of sympathetic
and parasympathetic neurotransmitter release and
their effects on target organs and tissues.
© 2015 Pearson Education, Inc.
An Introduction to the ANS and HigherOrder Functions
• Learning Outcomes.
• 16-4 Describe the hierarchy of interacting levels of
control in the autonomic nervous system,
including the significance of visceral reflexes.
• 16-5 Summarize the effects of aging on the
nervous system and give examples of
interactions between the nervous system
and other organ systems.
© 2015 Pearson Education, Inc.
An Introduction to the ANS and HigherOrder Functions
• Somatic Nervous System (SNS)
• Operates under conscious control
• Seldom affects long-term survival
• SNS controls skeletal muscles
• Autonomic Nervous System (ANS)
• Operates without conscious instruction
• ANS controls visceral effectors
• Coordinates vitals system functions
• Cardiovascular, respiratory, digestive, urinary,
reproductive
• 5 year survival after heart attack: increased since
1960
© 2015 Pearson Education, Inc.
16-1 Autonomic Nervous System
• Organization of the ANS
• Integrative centers  ViscMotN (PreGN)  G  PostGN 
Efec
• Integrative centers
• For autonomic activity in hypothalamus
• Neurons here are comparable to upper motor
neurons in SNS
• Synapses with ganglionic neurons
© 2015 Pearson Education, Inc.
16-1 Autonomic Nervous System
• Organization of the ANS
• Visceral motor neurons
• In brain stem and spinal cord, are known as
preganglionic neurons
• Preganglionic fibers
• Axons of preganglionic neurons
• Leave CNS and synapse on ganglionic neurons
© 2015 Pearson Education, Inc.
16-1 Autonomic Nervous System
• Visceral Motor Neurons
• Autonomic ganglia
• Contain many ganglionic neurons
• Ganglionic neurons innervate visceral effectors
• Such as cardiac muscle, smooth muscle, glands,
and adipose tissue
• Postganglionic fibers
• Axons of ganglionic neurons
© 2015 Pearson Education, Inc.
Figure 16-1a The Organization of the Somatic and Autonomic Nervous Systems.
Upper motor
neurons in
primary motor
cortex
Brain
Somatic motor
nuclei of brain
stem
Skeletal
muscle
Motor neurons of
the CNS exerts
direct control over
skeletal muscles
Lower
motor
neurons
Spinal cord
Somatic motor
nuclei of
spinal cord
Skeletal
muscle
a Somatic nervous system
© 2015 Pearson Education, Inc.
Figure 16-1b The Organization of the Somatic and Autonomic Nervous Systems.
Visceral motor
nuclei in
hypothalamus
Brain
Preganglionic
neuron
Visceral Effectors
Smooth
muscle
Autonomic
ganglia
Glands
Cardiac
muscle
Ganglionic
neurons
Autonomic
nuclei in
brain stem
Spinal cord
Adipocytes
Motor neurons of
the CNS synapse on
visceral motor neurons
in autonomic ganglia, and
these ganglionic neurons
control visceral effectors
© 2015 Pearson Education, Inc.
Autonomic
nuclei in
spinal cord
Preganglionic
neuron
b
Autonomic nervous system
16-1 Divisions of the ANS
• The Autonomic Nervous System
• Operates largely outside our awareness
• Control activities of target organs
• Modify or alter some ongoing activity
• Two divisions
1. Sympathetic division
• Increases alertness, metabolic rate, and muscular
abilities
• Kicks in only during exertion, stress, or emergency (F
or F)
2. Parasympathetic division
• Reduces metabolic rate and promotes digestion
• Controls during resting conditions (R and D)
© 2015 Pearson Education, Inc.
16-1 Divisions of the ANS
• Sympathetic and Parasympathetic Division
1. Most often, these two divisions have opposing
effects (antagonist)
• If the sympathetic division causes excitation, the
parasympathetic causes inhibition
2. The two divisions may also work independently
• Only one division innervates some structures
3. The two divisions may work together, with each
controlling one stage of a complex process
© 2015 Pearson Education, Inc.
16-1 Divisions of the ANS
• Sympathetic Division –Preganglionic fibers
originates in thoracic and superior lumbar;
(thoracolumbar, between T1 – L2 segments)
•
•
•
•
Synapse in ganglia near spinal cord
Preganglionic fibers are short
Postganglionic fibers are long
Prepares body for crisis, producing a “fight or
flight” response
• Stimulates tissue metabolism
• Increases alertness
© 2015 Pearson Education, Inc.
16-1 Divisions of the ANS
• Seven Responses to Increased Sympathetic
Activity
1.
2.
3.
4.
5.
Heightened mental alertness
Increased metabolic rate
Reduced digestive and urinary functions
Energy reserves activated
Increased respiratory rate and respiratory
passageways dilate
6. Increased heart rate and blood pressure
7. Sweat glands activated
© 2015 Pearson Education, Inc.
16-1 Divisions of the ANS
• Parasympathetic Division
• Preganglionic fibers originate in brain stem and
sacral segments of spinal cord; craniosacral
• Synapse in ganglia close to (or within) target
organs
• Preganglionic fibers are long
• Postganglionic fibers are short
• Parasympathetic division stimulates visceral
activity
• Conserves energy and promotes sedentary
activities
© 2015 Pearson Education, Inc.
16-1 Divisions of the ANS
• Five Responses to Increased Parasympathetic
Activity
1. Decreased metabolic rate
2. Decreased heart rate and blood pressure
3. Increased secretion by salivary and digestive
glands
4. Increased motility and blood flow in digestive
tract
5. Urination and defecation stimulation
© 2015 Pearson Education, Inc.
Figure 16-2 Overview of the Autonomic Nervous System (Part 1 of 2).
Sympathetic Division
(Thoracolumbar)
Preganglionic Neurons
Preganglionic neurons are
located in the lateral gray horns
of spinal segments T1–L2.
Ganglia
Ganglia are located near the
spinal cord. Preganglionic fibers
release acetylcholine (Ach),
stimulating ganglionic neurons.
Target Organs
Most postganglionic fibers
release norepinephrine (NE) at
neuroeffector junctions.
Sympathetic activation
“Fight or flight” response
KEY
Preganglionic fibers
Postganglionic fibers
© 2015 Pearson Education, Inc.
Figure 16-2 Overview of the Autonomic Nervous System (Part 2 of 2).
Parasympathetic Division
(Craniosacral)
Preganglionic Neurons
Preganglionic neurons in brain
stem and in lateral portion of
anterior gray horns of S2–S4.
Ganglia
Ganglia are in or near the target
organ. Preganglionic fibers
release acetylcholine (Ach),
stimulating ganglionic neurons.
Target Organs
All postganglionic fibers
release Ach at neuroeffector
junctions.
Parasympathetic stimulation
“Rest and digest” response
KEY
Preganglionic fibers
Postganglionic fibers
© 2015 Pearson Education, Inc.
16-1 Divisions of the ANS
• Enteric Nervous System (ENS)
• Third division of ANS
• Extensive network in digestive tract walls
• Complex visceral reflexes coordinated locally plus
influence of sympathetic and parasympathethic
divisions
• Neurotransmitters are the same found in the brain
© 2015 Pearson Education, Inc.
16-2 The Sympathetic Division
• Ganglionic Neurons
• Occur in three locations
1. Sympathetic chain ganglia
• On both sides of vertebral column (paravertebral)
• Control effectors:
• In body wall
• Inside thoracic cavity
• In head, and limbs
2. Collateral ganglia
• Are anterior to vertebral bodies (prevertebral)
• Innervate tissues and organs in abdominopelvic cavity
© 2015 Pearson Education, Inc.
Figure 16-3a Sites of Ganglia in Sympathetic Pathways.
a
SYMPATHETIC CHAIN GANGLIA
Spinal nerve Preganglionic
neuron
Autonomic ganglion of
right sympathetic chain
Autonomic ganglion
of left sympathetic chain
Innervates
visceral
effectors by
spinal nerves
White
ramus
Sympathetic nerve
(postganglionic
fibers)
Ganglionic
neuron
Gray ramus
Innervates visceral
organs in thoracic
cavity by
sympathetic nerves
Note: Both innervation patterns
occur on each side of the body.
© 2015 Pearson Education, Inc.
KEY
Preganglionic neurons
Ganglionic neurons
Figure 16-3b Sites of Ganglia in Sympathetic Pathways.
COLLATERAL GANGLIA
b
Lateral gray horn
White
ramus
Splanchnic nerve
(preganglionic
fibers)
Postganglionic
fibers
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Collateral
ganglion
Innervates
visceral organs in
abdominopelvic
cavity
16-2 The Sympathetic Division
• 3. Adrenal Medullae (Suprarenal Medullae)
•
•
•
•
Modified sympathetic ganglia
Center suprarenal medulla
Very short axons
When stimulated, release neurotransmitters into
bloodstream (not at synapse)
• Neurotransmitters then function as hormones to
affect target cells throughout body
© 2015 Pearson Education, Inc.
Figure 16-3c Sites of Ganglia in Sympathetic Pathways.
c
Preganglionic fibers
Endocrine cells
(specialized ganglionic
neurons)
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THE ADRENAL MEDULLAE
Adrenal
medullae
Secretes
neurotransmitters
into general
circulation
16-2 The Sympathetic Division
• Fibers in Sympathetic Division
• Preganglionic fibers
• Are relatively short
• Ganglia located near spinal cord
• Postganglionic fibers
• Are relatively long
• Except at adrenal medullae
© 2015 Pearson Education, Inc.
16-2 The Sympathetic Division
• Organization and Anatomy of the Sympathetic
Division
• Ventral roots of spinal segments T1–L2 contain
sympathetic preganglionic fibers
• Carry myelinated preganglionic fibers into
sympathetic chain ganglion
• May synapse at collateral ganglia or in adrenal
medullae
© 2015 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Chain Ganglia
• Preganglionic fibers
• One preganglionic fiber synapses on many ganglionic
neurons
• Fibers interconnect sympathetic chain ganglia
• Each ganglion innervates particular body segment(s)
• Preganglionic neurons
• Limited to spinal cord segments T1–L2
• White rami (myelinated preganglionic fibers)
• Innervate neurons in:
• Cervical, inferior lumbar, and sacral sympathetic chain
ganglia
© 2015 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Chain Ganglia
• Postganglionic fibers control visceral effectors
• In body wall, head, neck, or limbs
• Postganglionic fibers innervate effectors
• Sweat glands of skin
• Smooth muscles in superficial blood vessels
• Postganglionic fibers innervating structures in
thoracic cavity form bundles
• Sympathetic nerves
© 2015 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Chain Ganglia
• Postganglionic sympathetic fibers
• In head and neck leave superior cervical
sympathetic ganglia
• Supply the regions and structures innervated by
cranial nerves III, VII, IX, X
© 2015 Pearson Education, Inc.
Figure 16-4 The Distribution of Sympathetic Innervation (Part 2 of 4).
Eye
Pons
Salivary
glands
Sympathetic nerves
Heart
Cardiac and
pulmonary
plexuses
T1
T2
T3
T4
KEY
Preganglionic fibers
Postganglionic fibers
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Lung
Figure 16-4 The Distribution of Sympathetic Innervation (Part 3 of 4).
T1
T2
T3
T4
T5
T6
T7
KEY
Greater
splanchnic
nerve
Preganglionic fibers
Postganglionic fibers
Celiac ganglion
Superior
mesenteric
ganglion
Liver and
gallbladder
T8
T9
T10
T11
T12
L1
L2
L3
L4
L5
S1
S2
S3
S4
Stomach
Lesser
splanchnic
nerve
Spleen
Pancreas
Large intestine
Lumbar
splanchnic nerves
Small intestine
Inferior
mesenteric
ganglion
Adrenal
medulla
Sacral
splanchnic
nerves
Kidney
S5
Coccygeal
ganglia (Co1)
fused together
(ganglion impar)
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Uterus Ovary
Penis Scrotum
Urinary bladder
16-2 The Sympathetic Division
• Collateral Ganglia
• Receive sympathetic innervation via sympathetic
preganglionic fibers
• Splanchnic nerves
• Formed by preganglionic fibers that innervate
collateral ganglia
• In dorsal wall of abdominal cavity
© 2015 Pearson Education, Inc.
16-2 The Sympathetic Division
• Collateral Ganglia
• Postganglionic fibers
• Innervate variety of visceral tissues and organs
• Reduction of blood flow and energy by organs
not vital to short-term survival
• Release of stored energy reserves
© 2015 Pearson Education, Inc.
16-2 The Sympathetic Division
• Collateral Ganglia
• Preganglionic fibers from inferior thoracic
segments
• End at celiac ganglion or superior mesenteric
ganglion
• Preganglionic fibers from lumbar segments
• Form splanchnic nerves
• End at inferior mesenteric ganglion
© 2015 Pearson Education, Inc.
16-2 The Sympathetic Division
• Collateral Ganglia
• Celiac ganglion
• Postganglionic fibers innervate stomach, liver,
gallbladder, pancreas, and spleen
• Superior mesenteric ganglion
• Postganglionic fibers innervate small intestine and
proximal 2/3 of large intestine
• Inferior mesenteric ganglion
• Postganglionic fibers provide sympathetic innervation
to portions of:
•
•
•
•
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Large intestine
Kidney
Urinary bladder
Sex organs
16-2 The Sympathetic Division
• Adrenal Medullae
• Preganglionic fibers entering adrenal gland proceed
to center (adrenal medulla)
• Modified sympathetic ganglion
• Preganglionic fibers synapse on neuroendocrine
cells
• Specialized neurons secrete hormones into
bloodstream
© 2015 Pearson Education, Inc.
16-2 The Sympathetic Division
• Adrenal Medullae
• Neuroendocrine cells
• Secrete neurotransmitters epinephrine (E) and
norepinephrine (NE)
• Epinephrine
• Also called adrenaline
• Is 75–80 percent of secretory output
• Remaining is norepinephrine (NE)
• Noradrenaline
© 2015 Pearson Education, Inc.
16-2 The Sympathetic Division
• Adrenal Medullae
• Bloodstream carries neurotransmitters through
body
• Causing changes in metabolic activities of
different cells
• Including cells NOT innervated by sympathetic
postganglionic fibers
• Effects last longer
• Hormones continue to diffuse out of bloodstream
© 2015 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Activation
• Change activities of tissues and organs by:
• Releasing NT at peripheral synapses
• Distributing E and NE throughout body in
bloodstream
• Target specific effectors, smooth muscle fibers in
blood vessels of skin
• Are activated in reflexes
• Do not involve other visceral effectors
© 2015 Pearson Education, Inc.
16-2 The Sympathetic Division
• Changes Caused by Sympathetic Activation
•
•
•
•
•
Increased alertness
Feelings of energy and euphoria
Change in breathing
Elevation in muscle tone
Mobilization of energy reserves
© 2015 Pearson Education, Inc.
16-3 Various Sympathetic Neurotransmitters
• Stimulation of Sympathetic Preganglionic Neurons
• Releases ACh at synapses with ganglionic neurons
• Excitatory effect on ganglionic neurons
• Ganglionic Neurons
• Release neurotransmitters (NE, ACh) at specific
target organs
© 2015 Pearson Education, Inc.
16-3 Various Sympathetic Neurotransmitters
• Ganglionic Neurons
• Axon terminals
• Release NE at most varicosities
• Called adrenergic neuron
• Monoamine oxidase (MAO)
• Catechol O methyltransferase (COMT)
• Some ganglionic neurons release ACh instead
• Are located in body wall, skin, brain, and skeletal
muscles
• Called cholinergic neurons
• AChe
© 2015 Pearson Education, Inc.
Figure 16-5 Sympathetic Varicosities.
Preganglionic fiber
(myelinated)
Ganglionic
neuron
Ganglion
Postganglionic fiber
(unmyelinated)
Varicosities
Vesicles containing
norepinephrine (NE)
Mitochondrion
Schwann cell
cytoplasm
5 μm
Smooth muscle cells
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Varicosities
16-3 Various Sympathetic Neurotransmitters
• Sympathetic Stimulation and the Release of NE and E
• Effects occurs primarily from interactions of NE and E
with:
1. Alpha receptors
- NE more potent
- E same potency
2. Beta receptors
- NE less potent
- E same potency
• Two types of adrenergic membrane receptors
• Activates enzymes on inside of cell membrane via G
proteins (2nd messengers)
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16-3 Various Sympathetic Neurotransmitters
• Alpha receptors
• Alpha-1 (1)
• More common type of alpha receptor
• Releases intracellular calcium ions from reserves
in endoplasmic reticulum
• Has excitatory effect on target cell
• In smooth muscles
• Vessels constriction
• Closing sphincters
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16-3 Various Sympathetic Neurotransmitters
• Alpha receptors
• Alpha-2 (2)
• Lowers cAMP levels in cytoplasm
• Has inhibitory effect on the cell
• Helps coordinate sympathetic and parasympathetic
activities
• When sympathetic division is active:
• NE is released
• Binds to 2, on parasympathetic efectors
(neuromuscular and neuroglandular) and inhibits
their activity
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16-3 Various Sympathetic Neurotransmitters
• Beta () receptors
• Affect membranes in many organs (skeletal muscles,
lungs, heart, and liver)
• Trigger metabolic changes in target cell via G proteins
• Stimulation increases intracellular cAMP levels
• Three Main Types of Beta Receptors
1. Beta-1 (1)
2. Beta-2 (2)
3. Beta-3 (3)
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16-3 Various Sympathetic Neurotransmitters
• Three Main Types of Beta Receptors
1. Beta-1 (1)
• Increases metabolic activity, skeletal muscle
• Heart, increase heart rate and force of contraction
2. Beta-2 (2) (inhibition)
• Triggers relaxation of smooth muscles along
respiratory tract
• Easier breathing, respiratory therapy
3. Beta-3 (3)
• Leads to lipolysis, the breakdown of triglycerides in
adipocytes
• Make fatty acids available for other tissues
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16-3 Various Sympathetic Neurotransmitters
• Sympathetic Stimulation and the Release of Ach
• Cholinergic (ACh) sympathetic terminals
• Innervate sweat glands of skin and blood vessels
of skeletal muscles and brain
• Stimulate sweat gland secretion and dilate blood
vessels
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16-3 Various Sympathetic Neurotransmitters
• Sympathetic Stimulation and the Release of NO
• Nitroxidergic synapses
• Release nitric oxide (NO) as neurotransmitter
• Neurons innervate smooth muscles in walls of
blood vessels in skeletal muscles and the brain
• Produce vasodilation and increased blood flow
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Summary: Sympathetic Division
• Includes:
• 2 sets of chain ganglia
• 3 collateral ganglia
• two adrenal ganglia
• Preganglionic fibers shorts, post ganglionic are long
• ganglia are near spinal cord
• Adrenal: very short fibers direct to bloodstream
• Extensive divergence:
• a single sympathetic motor neuron can control a
variety of visceral effectors producing a complex and
coordinated response.
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Summary: Sympathetic Division
•All preG neurons release ACh at synapses with
ganglionic neurons
•Most postG neurons release NE
• a few release Ach or NO
•The effector response depends on the 2nd
messenger triggered by activation of G proteins by
NE o E to α or β receptors.
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16-4 The Parasympathetic Division
• Autonomic Nuclei
• Preganglionics neurons
• Are contained in the mesencephalon, pons, and
medulla oblongata
• Associated with cranial nerves III, VII, IX, X
• In lateral gray horns of spinal segments S2–S4
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16-4 The Parasympathetic Division
• Ganglionic Neurons in Peripheral Ganglia
• Terminal ganglion
• Near target organ
• Usually paired
• Intramural ganglion
• Embedded in or within tissues of target organ
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16-4 The Parasympathetic Division
• Organization and Anatomy of the
Parasympathetic Division
• Parasympathetic preganglionic fibers leave brain
as components of cranial nerves
•
•
•
•
III (oculomotor)
VII (facial)
IX (glossopharyngeal)
X (vagus)
• Parasympathetic preganglionic fibers leave spinal
cord at sacral level
• S2-S4
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16-4 The Parasympathetic Division
• Oculomotor(III), Facial(VII), and
Glossopharyngeal Nerves(IX)
• Control visceral structures in head
• Synapse in ganglia;
•
•
•
•
ciliary
pterygopalatine,
submandibular
otic ganglia
• Short postganglionic fibers continue to their
peripheral targets
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16-4 The Parasympathetic Division
• Vagus Nerve(X)
• Provides preganglionic parasympathetic
innervation to structures in:
• Neck
• Thoracic and abdominopelvic cavities
• as distant as a distal portion of large intestine
• Provides 75 percent of all parasympathetic
outflow
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Figure 16-6 The Distribution of Parasympathetic Innervation (Part 1 of 2).
Pterygopalatine ganglion
N III
Lacrimal gland
Eye
Ciliary ganglion
Pons
N VII
N IX
Submandibular
ganglion
Salivary glands
Otic ganglion
N X (Vagus)
Heart
Lungs
Oculomotor(III)
Facial(VII)
Glossopharyngeal Nerves(IX)
Vagus (X)
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16-4 The Parasympathetic Division
• Sacral Segments of Spinal Cord
• Preganglionic fibers carry sacral parasympathetic
output
• Do not join ventral roots of spinal nerves, instead
form pelvic nerves
•
•
•
•
•
Pelvic nerves innervate intramural ganglia in walls of:
kidneys
urinary bladder
portions of large intestine
sex organs
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Figure 16-6 The Distribution of Parasympathetic Innervation (Part 2 of 2).
Lungs
Autonomic plexuses
(see Figure 16-8)
Liver and
gallbladder
Stomach
Spleen
Pancreas
Large intestine
Pelvic
nerves
Small intestine
Rectum
Spinal
cord
Kidney
S2
S3
S4
KEY
Preganglionic fibers
Postganglionic fibers
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Uterus Ovary
Penis Scrotum
Urinary bladder
16-4 The Parasympathetic Division
• Parasympathetic Activation
•
•
•
•
•
•
centers on relaxation
food processing
energy absorption
localized effects
last a few seconds at most
Anabolic system
• Raisin up nutrient content in the blood
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16-4 The Parasympathetic Division
• Major Effects of Parasympathetic Division
• Constriction of the pupils
• To restrict the amount of light that enters the eyes
• Focusing of the lenses of the eyes on nearby
objects
• Secretion by digestive glands
• Salivary, gastric glands, intestinal glands
• the pancreas (exocrine and endocrine)
• the liver
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16-4 The Parasympathetic Division
• Major Effects of Parasympathetic Division
• Secretion of hormones
• Promote the absorption and utilization of nutrients
by peripheral cells
• Changes in blood flow and glandular activity
• Associated with sexual arousal
• Increase in smooth muscle activity
• Along the digestive tract, peristalsis
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16-4 The Parasympathetic Division
• Major Effects of Parasympathetic Division
• Stimulation and coordination of defecation
• Contraction of the urinary bladder during
urination
• Constriction of the respiratory passageways
• Reduction in heart rate and in the force of
contraction
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16-5 Parasympathetic Neurons Release ACh
• Neuromuscular and Neuroglandular Junctions
• All PS fibers release ACh as neurotransmitter
• Effects of stimulation are short lived
• Inactivated by acetylcholinesterase (AChE) at
synapse
• ACh is also inactivated by tissue cholinesterase in
surrounding tissues
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16-5 Parasympathetic Neurons Release ACh
• Two Types of Membrane Receptors and Responses
• Nicotinic receptors
• On surfaces of ganglion cells (sympathetic and
parasympathetic)
• On neuromuscular junction of Somatic Nervous
System
• Exposure to ACh causes excitation of ganglionic
neuron or muscle fiber
• Open Na+ channels in post sinaptic membrane
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16-5 Parasympathetic Neurons Release ACh
• Muscarinic receptors
• At cholinergic neuromuscular or neuroglandular
junctions (parasympathetic)
• At few cholinergic junctions (sympathetic)
• G proteins
• Effects are longer lasting than nicotinic receptors
• Can be excitatory or inhibitory
• Response reflects activation or inactivation of
specific enzymes
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16-5 Parasympathetic Neurons Release ACh
• Dangerous Environmental Toxins
• Produce exaggerated, uncontrolled responses
• Nicotine
• 3mg/g on tobacco
• Binds to nicotinic receptors
• Targets autonomic ganglia and skeletal
neuromuscular junctions
• Poisoning with 50 mg ingested or absorbed through
skin
• Signs and symptoms:
• Vomiting, diarrhea, high blood pressure, rapid heart rate,
sweating, profuse salivation, convulsions
• May result in coma or death
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16-5 Parasympathetic Neurons Release ACh
• Dangerous Environmental Toxins
• Produce exaggerated, uncontrolled responses
• Muscarine
• Binds to muscarinic receptors
• Targets parasympathetic neuromuscular or
neuroglandular junctions
• Signs and symptoms:
• Salivation, nausea, vomiting, diarrhea, constriction
of respiratory passages, low blood pressure, slow
heart rate (bradycardia)
• Sweating
• Amanita muscaria
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Amanita muscaria
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Table 16-1 Adrenergic and Cholinergic Receptors of the ANS.
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16-6 Dual Innervation: S y PS interaction
• Sympathetic Division
• Widespread impact
• Reaches organs and tissues throughout body
• Parasympathetic Division
• Innervates only specific visceral structures
• Sympathetic and Parasympathetic Division
• Most vital organs receive instructions from both
sympathetic and parasympathetic divisions
• Dual innervation
• Two divisions commonly have opposing effects
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Figure 16-7 Summary: The Anatomical Differences between the Sympathetic and Parasympathetic
Divisions.
Sympathetic
Parasympathetic
CNS
Preganglionic
neuron
PNS
Preganglionic
fiber
Sympathetic
ganglion
KEY
Neurotransmitters
Acetylcholine
Norepinephrine
or
Epinephrine
Ganglionic
neurons
Bloodstream
Postganglionic
fiber
TARGET
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Parasympathetic
ganglion
Table 16-2 A Structural Comparison of the Sympathetic and Parasympathetic
Divisions of the ANS.
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16-6 Dual Innervation
• Anatomy of Dual Innervation
• Parasympathetic postganglionic fibers accompany
cranial nerves to peripheral destinations
• Sympathetic innervation reaches same structures
• By traveling directly from superior cervical ganglia
of sympathetic chain
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Table 16-3 A Functional Comparison of the Sympathetic and Parasympathetic
Divisions of the ANS (Part 1-2 of 4).
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Table 16-3 A Functional Comparison of the Sympathetic and Parasympathetic
Divisions of the ANS (Part 3-4 of 4).
© 2015 Pearson Education, Inc.
16-6 Dual Innervation
• Anatomy of Dual Innervation
• Autonomic plexuses
• Nerve networks in the thoracic and abdominopelvic
cavities
• Are formed by mingled
• sympathetic postganglionic fibers and
parasympathetic preganglionic fibers
• Travel with blood and lymphatic vessels that supply
visceral organs
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16-6 Dual Innervation
• Anatomy of Dual Innervation
•
•
•
•
•
•
Cardiac plexus
Pulmonary plexus
Esophageal plexus
Celiac plexus
Inferior mesenteric plexus
Hypogastric plexus
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Figure 16-8 The Autonomic Plexuses and Ganglia (Part 1 of 2).
Aortic arch
Right vagus nerve
Autonomic Plexuses
and Ganglia
Cardiac plexus
Pulmonary plexus
Thoracic sympathetic
chain ganglia
Esophageal plexus
Celiac plexus
and ganglion
Superior mesenteric
ganglion
Inferior mesenteric
plexus and ganglia
Hypogastric plexus
Pelvic sympathetic
chain
© 2015 Pearson Education, Inc.
Figure 16-8 The Autonomic Plexuses and Ganglia (Part 1 of 2).
Aortic arch
Right vagus nerve
Trachea
Autonomic Plexuses
and Ganglia
Cardiac plexus
Pulmonary plexus
Left vagus nerve
Thoracic spinal nerves
Esophagus
Thoracic sympathetic
chain ganglia
Esophageal plexus
Splanchnic nerves
Celiac plexus
and ganglion
Superior mesenteric
ganglion
Diaphragm
Superior mesenteric artery
Inferior mesenteric
plexus and ganglia
Hypogastric plexus
Pelvic sympathetic
chain
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Inferior mesenteric artery
16-6 Dual Innervation
• Autonomic Tone
• Is an important aspect of ANS function
• If nerve is inactive under normal conditions, can
only increase activity
• If nerve maintains background level of activity, can
increase or decrease activity
• Significant where dual innervation occurs
• Two divisions have opposing effects
• Heart
• More important when dual innervation does not
occur
• Blood vessels
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16-6 Dual Innervation
• The Heart Receives Dual Innervation
• Two divisions have opposing effects on heart
function
1. Parasympathetic division
• Acetylcholine released by postganglionic fibers
slows heart rate
2. Sympathetic division
• NE released by varicosities accelerates heart rate
• Balance between two divisions
• Autonomic tone is present
• Releases small amounts of both neurotransmitters
continuously
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16-6 Dual Innervation
• The Heart Receives Dual Innervation
• Parasympathetic innervation dominates under
resting conditions
• Crisis accelerates heart rate by:
• Stimulation of sympathetic innervation
• Inhibition of parasympathetic innervation
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16-6 Dual Innervation
• Autonomic Tone
• Blood vessel dilates and blood flow increases
• Blood vessel constricts and blood flow is reduced
• Sympathetic postganglionic fibers release NE
• Innervate smooth muscle cells in walls of
peripheral vessels
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16-6 Dual Innervation
• Autonomic Tone
• Background sympathetic tone keeps muscles
partially contracted
• To increase blood flow:
•
•
•
•
Rate of NE release decreases
Sympathetic cholinergic fibers are stimulated
Smooth muscle cells relax
Vessels dilate and blood flow increases
© 2015 Pearson Education, Inc.
16-7 Visceral Reflexes Regulate the ANS
• Visceral Reflexes
• Provide automatic motor responses
• Can be modified, facilitated, or inhibited by higher
centers, especially hypothalamus
• Visceral reflex arc
• Receptor
• Sensory neuron
• Processing center (one or more interneurons)
• All polysynaptic
• Two visceral motor neurons
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16-7 Visceral Reflexes Regulate the ANS
• Visceral Reflexes
• Long reflexes
• Visceral sensory neurons deliver information to CNS
• ANS carries motor commands to visceral effectors
• Coordinate activities of entire organ
• Short reflexes
• Bypass CNS
• Control simple motor responses with localized effects
• One small part of target organ
© 2015 Pearson Education, Inc.
Figure 16-9 Visceral Reflexes.
Receptors in
peripheral tissue
Afferent (sensory)
fibers
CENTRAL NERVOUS
SYSTEM
Stimulus
Long
reflex
Short
reflex
Processing center
in spinal cord
Response
Peripheral
effector
Postganglionic
neuron
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Autonomic ganglion
Preganglionic
(sympathetic or
neuron
parasympathetic)
16-7 Visceral Reflexes Regulate the ANS
• Visceral Reflexes
• Regulating visceral activity
• Most organs
• Long reflexes most important
• Digestive tract
• Short reflexes provide most control and coordination
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Table 16-4 Representative Visceral Reflexes (Part 1 of 2).
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16-7 Visceral Reflexes Regulate the ANS
• The Integration of SNS and ANS Activities
• Many parallels in organization and function
• Integration at brain stem
• Both systems under control of higher centers
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Table 16-5 A Comparison of the ANS and SNS.
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16-10 Effects of Aging on the Nervous
System
• Effects of Aging
• Anatomical and physiological changes begin after
maturity (age 30)
• Accumulate over time
• 85 percent of people over age 65 have changes in
mental performance and CNS function
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16-10 Effects of Aging on the Nervous
System
• Reduction in Brain Size and Weight
• Decrease in volume of cerebral cortex
• Narrower gyri and wider sulci
• Larger subarachnoid space
• Reduction in Number of Neurons
• Brain shrinkage linked to loss of cortical neurons
• No neuronal loss in brain stem nuclei
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16-10 Effects of Aging on the Nervous
System
• Decrease in Blood Flow to Brain
• Arteriosclerosis
• Fatty deposits in walls of blood vessels
• Reduces blood flow through arteries
• Increases chances of rupture
• Cerebrovascular accident (CVA), or stroke
• May damage surrounding neural tissue
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16-10 Effects of Aging on the Nervous
System
• Changes in Synaptic Organization of Brain
• Number of dendritic branches, spines, and
interconnections decreases
• Synaptic connections lost
• Rate of neurotransmitter production declines
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16-10 Effects of Aging on the Nervous
System
• Intracellular and Extracellular Changes in CNS
Neurons
• Neurons in brain accumulate abnormal
intracellular deposits
• Lipofuscin
• Granular pigment with no known function
• Neurofibrillary tangles
• Masses of neurofibrils form dense mats inside cell
body and axon
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16-10 Effects of Aging on the Nervous
System
• Intracellular and Extracellular Changes in CNS
Neurons
• Plaques
• Extracellular accumulations of fibrillar proteins
• Surrounded by abnormal dendrites and axons
© 2015 Pearson Education, Inc.
16-10 Effects of Aging on the Nervous
System
• Intracellular and Extracellular Changes in CNS
Neurons
• Plaques and tangles
• Contain deposits of several peptides
• Primarily two forms of amyloid ß (Aß) protein
• Appear in brain regions specifically associated with
memory processing
© 2015 Pearson Education, Inc.
16-10 Effects of Aging on the Nervous
System
• Anatomical Changes
•
•
•
•
Linked to functional changes
Neural processing becomes less efficient with age
Memory consolidation more difficult
Secondary memories harder to access
© 2015 Pearson Education, Inc.
16-10 Effects of Aging on the Nervous
System
• Sensory Systems
• Hearing, balance, vision, smell, and taste become
less acute
• Reaction times slowed
• Reflexes weaken or disappear
• Motor Control
• Precision decreases
• Takes longer to perform
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16-10 Effects of Aging on the Nervous
System
• Incapacitation
• 85 percent of elderly population develops changes
that do not interfere with abilities
• Some individuals become incapacitated by
progressive CNS changes
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16-10 Effects of Aging on the Nervous
System
• Senility
• Also called senile dementia
• Degenerative changes
• Memory loss
• Anterograde amnesia (lose ability to store new
memories)
• Emotional disturbances
• Alzheimer’s disease is most common
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16-10 Nervous System Integration
• The Nervous System
• Monitors all other systems
• Issues commands that adjust their activities
• Like conductor of orchestra
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16-10 Nervous System Integration
• Neural Tissue
• Extremely delicate
• Extracellular environment must maintain
homeostatic limits
• If regulatory mechanisms break down,
neurological disorders appear
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Figure 16-14 diagrams the functional relationships between the nervous system and other body systems we have studied so far.
I N T E G R A T O R
Provides calcium ions for neural
function; protects brain and spinal cord
Controls skeletal muscle contractions
that results in bone thickening and
maintenance and determine bone
position
Facial muscles express emotional
state; intrinsic laryngeal muscles
permit communication; muscle
spindles provide proprioceptive
sensations
Controls skeletal muscle contractions;
coordinates respiratory and
cardiovascular activities
Page 174
Controls contraction of arrector pili
muscles and secretion of sweat glands
Skeletal
Provides sensations of touch, pressure,
pain, vibration, and temperature; hair
provides some protection and insulation
for skull and brain; protects peripheral
nerves
Integumentary
Body System
Page 285
Nervous System
Muscular
Integumentary
Skeletal
Muscular
Nervous System
Page 380
S Y S T E M
Body System
© 2015 Pearson Education, Inc.
Page 647
Page 776
Cardiovascular
Lymphatic
Page 824
Page 874
Respiratory
Digestive
Page 1090
Page 929
Urinary
Page 1010
Reproductive
The nervous system is closely integrated
with other body systems. Every moment
of your life, billions of neurons in your
nervous system are exchanging
information across
trillions of synapses and
performing the most
complex integrative
functions in the body. As
part of this process, the
nervous system monitors all
other systems and issues
commands that adjust their
activities. However, the
significance and impact of
these commands varies
greatly from one system to
another. The normal functions of the
muscular system, for example, simply
cannot be performed without
instructions from the nervous system. By
contrast, the cardiovascular system is
relatively independent—the nervous
system merely coordinates and adjusts
cardiovascular activities to meet the
circulatory demands of other systems. In
the final analysis, the nervous system is
like the conductor of an orchestra,
directing the rhythm and balancing the
performances of each section to produce
a symphony, instead of simply
a very loud noise.
Endocrine
The Nervous System