Download Sympathetic Division (cont)

BIO 168
NEURAL INTEGRATION II:
THE AUTONOMIC
NERVOUS SYSTEM AND
HIGHER ORDER
FUNCTIONS
CHAPTER 16
created by Dr. C. Morgan
1
TOPICS
Introduction and Overview of the ANS
The Sympathetic Division
The Parasympathetic Division
Sympathetic / Parasympathetic Interactions
Integration and Control
Higher Order Functions
Brain Chemistry and Behavior
Aging and the Nervous System
2
Introduction and Overview Objectives
Review the role of the autonomic nervous system
division.
Compare the organization of the ANS with the SNS.
Examine the structural and functional plan of the ANS.
3
Introduction and Overview
If you were unable to think or voluntarily move a muscle,
you would continue to survive because your autonomic
nervous system (ANS) takes care of vital functions
without your conscious awareness or control.
Although both the ANS and SNS generate efferent output to
effectors, there are important structural differences.
In the SNS, lower motor neurons control skeletal muscles.
In the ANS, there is a second visceral motor neuron that
originates from a synapse in a ganglion outside the CNS.
All autonomic nerves are motor although some may also
carry visceral sensory information.
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Introduction and Overview (cont)
Fig. 1
5
Introduction and Overview (cont)
SNS plan
Upper motor neuron in
the cortex.
Lower motor neuron in
the brain stem or
spinal cord.
All cell bodies are
within the CNS.
Fig. 2 a
6
Introduction and Overview (cont)
ANS plan
Preganglionic neuron
cell body in CNS
Postganglionic neuron
cell body outside CNS
Fig. 2 b
7
Introduction and Overview (cont)
ANS has two subdivisions: sympathetic and
parasympathetic, usually with opposing effects if they
innervate the same structure or organ.
The sympathetic division directs your “fight-or-flight” or crisis
responses (protective) with widespread, global output.
The parasympathetic division directs your “rest and repose”
ongoing visceral responses with localized output.
In the sympathetic division, sensory input is consciously
perceived but in the parasympathetic division it is not
consciously perceived.
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Introduction and Overview (cont)
The ANS also includes a huge network of neurons and
their processes contained within the wall of the digestive
tract.
This extensive network is sometimes called the enteric
nervous system (ENS).
This network has as many neurons as the spinal cord
and a large variety of neurotransmitters are used.
Reflexes within the digestive tract are initiated and
controlled locally without commands from the CNS.
The ANS does influence the activities along the
digestive tract.
9
TOPICS
Introduction and Overview of the ANS
The Sympathetic Division
The Parasympathetic Division
Sympathetic / Parasympathetic Interactions
Integration and Control
Higher Order Functions
Brain Chemistry and Behavior
Aging and the Nervous System
10
Sympathetic Division Objectives
Examine the structural arrangement of sympathetic
ganglia and their fibers.
Using an illustration, explore the distribution of the
sympathetic innervation.
Discuss the sympathetic chain ganglia and their
branching fiber arrangements.
Describe the characteristics of sympathetic activation.
Discuss neurotransmitter substances and sympathetic
function.
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Sympathetic Division
Sympathetic Division Plan
Fig. 3
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12
Sympathetic Division (cont)
Preganglionic fibers of the sympathetic division are
associated with spinal segments T1 to L2.
Cell bodies of preganglionic neurons are located in the
lateral gray horns of the spinal cord gray matter.
Preganglionic neurons synapse with neurons located in
ganglia outside the CNS.
These ganglia are found in three locations:
*in bilateral sympathetic chains adjacent to the spinal
column
*in peripheral collateral ganglia associated with effectors in
the abdominopelvic cavity
*in the adrenal medullae tissue proper
13
Sympathetic Division
bilateral
divergence
Fig. 5
14
Sympathetic Division (cont)
The sympathetic chain includes 3 cervical, 10 – 12 thoracic,
4 – 5 lumbar, 4 – 5 sacral, and 1 coccygeal ganglion.
Do not become confused—the cell bodies of preganglionic
neurons lie in the spinal cord between T1 and L2 but the
sympathetic chain ganglia extend along cervical to sacral
segments.
There is substantial divergent branching of preganglionic
fibers (ascending and descending) so that numerous
synapses from neuron collaterals may occur along the chain.
It is these fiber branches that produce the chain-like links
between the sympathetic (bead-like) ganglia.
15
Sympathetic Division (cont)
Sympathetic ganglia locations
via spinal nerves
both patterns
bilateral
Fig. 4 a
sweat glands,
blood vessels,
arrector pili
muscles,
adipose tissue
(1) Sympathetic chain
16
Sympathetic Division (cont)
(2) Passes through chain to collateral ganglion in abdomen
Fig. 4 b
Long preganglionic
neuron fibers
17
Sympathetic Division (cont)
(3) Directly in adrenal medullae
Long
preganglionic
neuron
Short postganglionic neuroendocrine cells
release epinephrine and norepinephrine
Fig. 4 c
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Sympathetic Division (cont)
Collateral ganglia
Celiac: stomach, liver,
spleen, pancreas
Superior Mesenteric:
small intestine
Inferior Mesenteric:
large intestine,
kidneys, bladder,
sex organs
Postganglionic
plexuses
Depresses visceral
processes
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Sympathetic Division (cont)
Splanchnic nerves are preganglionic fibers that pass
through chain ganglia to synapse in collateral ganglia
located in the abdominopelvic cavity.
Although splanchnic nerves are bilateral, they serve single
ganglia.
The ganglia are named for the nearby artery with which they
are associated.
In the adrenal medulla, preganglionic fibers synapse on
neuroendocrine cells which secrete epinephrine and
norepinephrine when they are depolarized at the synapse.
About 80% of the adrenal output is epinephrine.
Sympathetic visceral motor fibers are able to target specific
effectors such as blood vessels in the skin.
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Sympathetic Division (cont)
Sympathetic activation is the response of the entire
sympathetic division to a crisis situation.
Centers in the hypothalamus direct this response.
*RAS is stimulated causing increased alertness, energy,
temporary insensitivity to pain, disregard for danger
*Pons and medulla direct increased cardiovascular and
respiratory responses
*Increased muscle tone and perhaps shivering
*Mobilization of energy reserves to support increased
metabolism
Sympathetic activation supports a “fight-or-flight” response.
21
Sympathetic Division (cont)
Postganglionic fibers end in branching telodendria
Most varicosities
release E and NE
but some ganglionic
neurons release
ACh (sweat glands,
smooth muscle of
blood vessels in
brain and skeletal
muscle  dilation.
of telodendria
Fig. 6
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Sympathetic Division (cont)
2 types of E and NE neurotransmitter receptors
Alpha
Beta
Alpha 1(1): activates
second messenger to
 excitation
Beta 1(β1): activates
second messenger 
cAMP to increase cell
metabolism ( muscle
and liver responses)
Alpha 2 (2 ): reduces
cAMP to inhibit cell
activity; may inhibit
some parasympathetic
synapses
Beta 2 (β2): opposite of
beta 1 so decreases
responses
action depends on receptors and cellular response
TABLE 1
23
Sympathetic Division (cont)
The body wall and skeletal muscle blood vessels are only
innervated by the sympathetic division.
At most sites, the postganglionic telodendria release ACh
which stimulates sweat glands and dilates vasculature in
skeletal muscles (muscarinic receptors).
In body wall locations, some sympathetic telodendria
release NE (1 receptor response) which acts to constrict
arteries so blood flow is shifted to areas of critical need.
Nitric oxide is also released at a few sympathetic synapses
involving blood vessel walls of skeletal muscle and the
brain.
Nitric oxide causes immediate vasodilation.
24
TOPICS
Introduction and Overview of the ANS
The Sympathetic Division
The Parasympathetic Division
Sympathetic / Parasympathetic Interactions
Integration and Control
Higher Order Functions
Brain Chemistry and Behavior
Aging and the Nervous System
25
Parasympathetic Division Objectives
Examine the organization of the parasympathetic
division.
List the general functions of the parasympathetic
division.
Discuss the parasympathetic neurotransmitter
receptors.
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Parasympathetic Division
Organization
little divergence
midbrain, pons,
medulla
lateral gray horns
Fig. 7
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Parasympathetic Division (cont)
CRANIAL PORTION:
Preganglionic fibers extend from brain stem nuclei to ganglia.
Ganglia associated with cranial nerves III, VII, IX, X
Serves lacrimal and salivary glands; intrinsic eye muscles.
Vagus (75% of all outflow) to thoracic and abdominal organs
(terminal ganglia)
SACRAL PORTION:
Preganglionic fibers in spinal cord lateral gray horns (S2-S4)
with outflow via distinct pelvic nerves (not ventral roots) to
intramural ganglia in walls of visceral organs.
Innervates kidneys, urinary bladder, terminal large intestine,
and sex organs.
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Parasympathetic Division (cont)
Innervation Plan
Preganglionic
fibers
Ganglia
Plexuses
Pelvic nerves
Vagus nerve***
Fig. 8
29
Parasympathetic Division (cont)
Functions of the parasympathetic division include:
*constriction of pupils and nearby focusing of lens
*digestive system smooth muscular and secretory activity
*promotes hormones secretion supporting anabolic
activities
*micturition and defecation reflexes
*airway constriction
*reduction in heart rate and force of contraction
*sexual arousal and sex gland stimulation
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Parasympathetic Division (cont)
ACh and its receptors
All parasympathetic synapses use ACh
Effects are brief due to AChE and tissue cholinesterase
presence.
Effects are restricted to specific targets.
2 types of receptors for ACh
Nicotinic: Excitatory
TABLE 2
at all ganglionic synapses
Muscarinic: Excitatory or inhibitory
at parasympathetic neuromuscular and neuroglandular
junctions
31
TOPICS
Introduction and Overview of the ANS
The Sympathetic Division
The Parasympathetic Division
Sympathetic / Parasympathetic Interactions
Integration and Control
Higher Order Functions
Brain Chemistry and Behavior
Aging and the Nervous System
32
Sympathetic / Parasympathetic Interactions
Objectives
Review the innervation plan of the sympathetic and
parasympathetic divisions.
Discuss the anatomy of dual innervation.
Using an illustration, compare the two divisions.
Discuss the concept of autonomic tone.
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Sympathetic / Parasympathetic Interactions
The sympathetic division is widespread with innervation to
nearly all organs and tissues in the body.
The parasympathetic division innervates only those
structures associated with four cranial nerves and with
structures served by the pelvic nerves.
Most vital organs receive innervation from both divisions
with effects in opposition to one another.
This is especially important in the digestive tract, the heart,
and the lungs.
For the cranial nerves III, VII, IX and X, the postganglionic
fibers course along with the cranial nerves while the
sympathetic fibers travel from chain ganglia to some of
those same structures.
34
Sympathetic / Parasympathetic Interactions (cont)
Sympathetic
postganglionic
fibers +
parasympathetic
preganglionic
fibers form
autonomic
plexuses.
Fig. 9
35
Sympathetic / Parasympathetic Interactions (cont)
Comparison
Global
1:32
Fig. 10
TABLE 2
Local
1:6
36
Sympathetic / Parasympathetic Interactions (cont)
In visceral organs where there is dual innervation, there is a
certain amount of background output from each division
which is called autonomic tone.
Some regions and organs are innervated by one division
only (blood vessels–sympathetic).
Background sympathetic output maintains tone on the
peripheral blood vessels so that in order to achieve
dilation or constriction, only slight adjustments are
needed.
TABLE 3 lists a functional comparison of the ANS divisions.
37
TOPICS
Introduction and Overview of the ANS
The Sympathetic Division
The Parasympathetic Division
Sympathetic / Parasympathetic Interactions
Integration and Control
Higher Order Functions
Brain Chemistry and Behavior
Aging and the Nervous System
38
Integration and Control Objectives
Introduce the concept of integrating levels of control.
Discuss long and short visceral reflexes.
Examine higher levels of autonomic control.
Discuss the integration of SNS and ANS activities.
Describe the concept of biofeedback.
39
Integration and Control
Like the SNS, the ANS is organized into various interacting
levels of control.
Visceral reflexes represent the lowest level of interaction.
Visceral reflexes are comparable to somatic polysynaptic
reflexes.
Visceral reflexes are either long reflexes or short reflexes.
Long reflexes involve the CNS processing of sensory
information with ANS motor commands to visceral effectors
over a relatively large area or an entire organ.
Short reflexes bypass the CNS and synapse on interneurons
of autonomic ganglia for localized control of effectors.
Short reflexes control activity along small sections of the
digestive tract.
40
40
Integration and Control (cont)
Most visceral reflexes are parasympathetic.
TABLE 4
Fig. 11
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41
Integration and Control (cont)
There are centers in the brain stem that control specific
functions via the ANS.
Simple reflexes cause immediate responses to specific
stimuli.
Processing centers in the medulla coordinate many
complex parasympathetic and sympathetic reflexes.
The medulla controls the cardiovascular, respiratory,
salivation, swallowing, vomiting, digestive secretory,
peristaltic muscular contraction, and urinary functions.
The hypothalamus regulates the medullary centers.
Because of the widespread interaction of the hypothalamus
with other brain nuclei and cortical centers, ANS control
and integration becomes very complex.
42
Integration and Control (cont)
Levels of
Integration
and
autonomic
control
Fig. 12
43
Integration and Control (cont)
SNS and ANS
are both under
higher system
control.
Sensory input
may result in
output via the
SNS and ANS
simultaneously.
TABLE 5
Fig. 13
4444
Integration and Control (cont)
Biofeedback is an excellent example of higher center
control over some ANS functions.
Biofeedback is a mechanism that involves monitoring of
physiological processes which are “fed back” so a person
can invoke conscious thoughts to control them.
For example, blood pressure may be monitored.
The person is trained to relax and use mechanisms of
stress control to lower blood pressure.
The monitor informs the subject when pressure drops so
they are aware of the success of their control effort.
Biofeedback control is used for the management of
many disorders.
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TOPICS
Introduction and Overview of the ANS
The Sympathetic Division
The Parasympathetic Division
Sympathetic / Parasympathetic Interactions
Integration and Control
Higher Order Functions
Brain Chemistry and Behavior
Aging and the Nervous System
46
Higher-Order Functions Objectives
Discuss what is meant by higher-order functions.
Describe the types of memories.
Investigate the brain regions involved in memory
consolidation and access.
Discuss the cellular mechanisms involved with
memory.
Describe the state of consciousness.
Discuss sleep and arousal from sleep.
47
Higher-Order Functions
Higher-Order functions include:
Complex cortical interactions
Memory
Conscious activities / learning
Unconscious activities
Because higher-order functions do not involve
programmed functions such as reflexes, they are
subject to modification and adjustment over time.
48
Higher-Order Functions (cont)
Memories are bits of information stored in the cortex.
Fact memories are specific – red stop sign, smell of
pizza, shape of a car versus a truck, etc.
Skill memories are learned motor behavior patterns –
how to open a can, how to turn on the shower, etc.
With repetition, skill memories may be become part of
your unconscious or programmed behavioral patterns
such as eating, driving, swimming, golfing, etc.
Cerebral nuclei and the cerebellum will participate.
49
Higher-Order Functions (cont)
Short–term memories are primary, can be recalled
immediately, and last a short time.
Long–term memories are secondary and last much
longer—perhaps even a lifetime.
Consolidation converts short term memories to long ones.
There are two types of long–term memories:
*secondary memories that fade with time; difficult to recall
*tertiary memories that are part of your conscious being
such as knowing your name, knowing the contours of
your body
50
Higher-Order Functions (cont)
Memory Storage
Memory is complex
Fig. 14
Amnesia is the loss of memory.
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51
Higher-Order Functions (cont)
Regions involved in memory:
cerebral cortex — storage for long–term memories
with association areas important storage sites
hippocampus + amygdaloid body — convert short–term
memories to long–term memories
amygdaloid body — relates memories to emotions
nucleus basalis (near diencephalon) — some role in
storage and retrieval
The visual association area helps you remember what a
cat looks like, or your best friend; the speech center tells
you how to say the word “cat”, the auditory association
area tells you what “meow” sounds like and that it is a
cat call, etc.
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Higher-Order Functions (cont)
How memories are consolidated is poorly understood.
How they are retrieved is even less well understood.
What is known: a synapse that is frequently active does
increase its output of neurotransmitter to produce a
greater effect on the postsynaptic neuron(s).
Circuits that are repeatedly active release a low level of
neurotransmitter that results in facilitation of postsynaptic
neurons(s).
Highly active neurons establish increased numbers of
synapses with the postsynaptic neuron to produce a
greater effect.
A single circuit may correspond to a single long–term
memory (memory engram) and take 1 hour to form.
53
Higher-Order Functions (cont)
Consciousness is the degree of wakefulness and alertness.
If you are conscious, you are alert and attentive.
There are gradations in the degree of consciousness.
Sleep is an unconscious state from which you may be
awakened by normal sensory stimuli.
There are two levels of sleep, deep sleep (non–REM) and
rapid eye movement (REM) sleep.
In NREM sleep, the body relaxes and metabolism slows.
In REM sleep, dreaming occurs; you are less receptive to
sensory stimuli (around 2 hours per night).
REM and NREM alternate throughout the night.
54
Higher-Order Functions (cont)
Alpha waves
NREM Delta waves
Fig. 15
55
Higher-Order Functions (cont)
Arousal from sleep is
a function of the RAS
(reticular activating
system)
The RAS alerts your
thalamus which
stimulates the cortex.
Fig. 16
56
TOPICS
Introduction and Overview of the ANS
The Sympathetic Division
The Parasympathetic Division
Sympathetic / Parasympathetic Interactions
Integration and Control
Higher Order Functions
Brain Chemistry and Behavior
Aging and the Nervous System
57
Brain Chemistry and Behavior Objectives
Discuss the importance of understanding the
interplay between neurotransmitters.
Discuss the role of drugs or chemicals on
behavior.
List several chemical disorders that have
been documented to affect behavior.
58
Brain Chemistry and Behavior
We know that all neural communication is chemical and
that there are many neurotransmitter substances.
Awake – sleep cycles seem to depend on a balance
between serotonin and norepinephrine.
Drugs that block serotonin synthesis or binding induce
depression while drugs that prolong the presence of
serotonin (Prozac) are used to treat depression.
Drugs that stimulate NE producing neurons cause
excitement while those that inhibit those neurons produce
depression.
Too little dopamine causes Parkinsons’s and excessive
dopamine may lead to schizophrenia.
Personality is a mystery.
59
TOPICS
Introduction and Overview of the ANS
The Sympathetic Division
The Parasympathetic Division
Sympathetic / Parasympathetic Interactions
Integration and Control
Higher Order Functions
Brain Chemistry and Behavior
Aging and the Nervous System
60
Aging and the Nervous System Objectives
Describe some age–related anatomical changes
in the nervous system.
Describe some age–related functional changes
in the nervous system.
Discuss Alzheimer’s disease.
61
Aging and the Nervous System
The nervous system begins its decline about age 30.
Many individuals over age 65 may exhibit changes in
their CNS function as documented below.
Anatomical changes:
*The brain size declines as the cortex is reduced.
*The number of neurons in the cortex declines.
*Blood flow to the brain declines due to atherosclerosis.
*The number of synapses decreases and
neurotransmitter quantity likewise declines.
*Neurons may accumulate abnormal deposits consisting
of pigments, proteins (amyloid), or neurofibril tangles.
62
Aging and the Nervous System (cont)
Functional changes:
*Memory consolidation declines and access declines
especially for secondary memories (recent past).
*Sensory processing is less acute.
*Fine motor control is more difficult and reflexes are slower.
Alzheimer’s disease is a progressive loss of higher–order
functions that affects 15% of people over 65 and causes
100,000+ deaths / year in the U.S.
There is some evidence that several genes may be
responsible for the development of senile dementia,
especially Alzheimer’s.
63
TOPICS
Introduction and Overview of the ANS
The Sympathetic Division
The Parasympathetic Division
Sympathetic / Parasympathetic Interactions
Integration and Control
Higher Order Functions
Brain Chemistry and Behavior
Aging and the Nervous System
64