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16
Neural Integration II:
The Autonomic
Nervous System and
Higher-Order
Functions
PowerPoint® Lecture Presentations prepared by
Jason LaPres
Lone Star College—North Harris
© 2012 Pearson Education, Inc.
An Introduction to the ANS and Higher-Order
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 division of the autonomic nervous
system.
• 16-3 Describe the mechanisms of sympathetic
neurotransmitter release and their effects on
target organs and tissues.
© 2012 Pearson Education, Inc.
An Introduction to the ANS and Higher-Order
Functions
• Learning Outcomes
• 16-4 Describe the structures and functions of the
parasympathetic division of the autonomic nervous
system.
• 16-5 Describe the mechanisms of parasympathetic
neurotransmitter release and their effects on target
organs and tissues.
• 16-6 Discuss the functional significance of dual
innervation and autonomic tone.
• 16-7 Describe the hierarchy of interacting levels of
control in the autonomic nervous system, including
the significance of visceral reflexes.
© 2012 Pearson Education, Inc.
An Introduction to the ANS and Higher-Order
Functions
• Learning Outcomes
• 16-8 Explain how memories are created, stored, and
recalled, and distinguish among the levels of
consciousness and unconsciousness.
• 16-9 Describe some of the ways in which the
interactions of neurotransmitters influence brain
function.
• 16-10 Summarize the effects of aging on the nervous
system and give examples of interactions
between the nervous system and other organ
systems.
© 2012 Pearson Education, Inc.
An Introduction to the ANS and Higher-Order
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 system functions
• Cardiovascular, respiratory, digestive, urinary, reproductive
© 2012 Pearson Education, Inc.
Figure 16-1 An Overview of Neural Integration
OVERVIEW OF NEURAL INTEGRATION
CHAPTER 16
CHAPTER 15
Sensory
processing
centers in
brain
Sensory
pathways
Conscious and
subconscious
motor centers
in brain
© 2012 Pearson Education, Inc.
Memory, learning, and
intelligence may
influence interpretation
of sensory information
and nature of motor
activities
Motor
pathways
Somatic
Nervous
System (SNS)
General
sensory
receptors
Higher-Order Functions
Skeletal
muscles
Autonomic
Nervous
System (ANS)
Visceral effectors
(examples: smooth
muscle, glands,
cardiac muscle,
adipocytes)
16-1 Autonomic Nervous System
• Organization of the ANS
• Integrative centers
• For autonomic activity in hypothalamus
• Neurons comparable to upper motor neurons in SNS
© 2012 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
© 2012 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
© 2012 Pearson Education, Inc.
Figure 16-2a 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
Lower
motor
neurons
SPINAL
CORD
Somatic
motor nuclei
of spinal cord
Skeletal
muscle
Somatic nervous system
© 2012 Pearson Education, Inc.
Figure 16-2b The Organization of the Somatic and Autonomic Nervous Systems
Visceral motor
nuclei in
hypothalamus
BRAIN
Preganglionic
neuron
Visceral Effectors
Smooth
muscle
Glands
Cardiac
muscle
Autonomic
ganglia
Ganglionic
neurons
Adipocytes
Preganglionic
neurons
Autonomic
nuclei in
brain stem
SPINAL
CORD
Autonomic
nuclei in
spinal cord
Autonomic nervous system
© 2012 Pearson Education, Inc.
16-1 Divisions of the ANS
• The Autonomic Nervous System
•
Operates largely outside our awareness
•
Has two divisions
1. Sympathetic division
•
Increases alertness, metabolic rate, and muscular
abilities
2. Parasympathetic division
•
Reduces metabolic rate and promotes digestion
© 2012 Pearson Education, Inc.
16-1 Divisions of the ANS
• Sympathetic Division
• “Kicks in” only during exertion, stress, or
emergency
• “Fight or flight”
• Parasympathetic Division
• Controls during resting conditions
• “Rest and digest”
© 2012 Pearson Education, Inc.
16-1 Divisions of the ANS
• Sympathetic and Parasympathetic Division
1. Most often, these two divisions have opposing effects
• 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
© 2012 Pearson Education, Inc.
16-1 Divisions of the ANS
• Sympathetic Division
• Preganglionic fibers (thoracic and superior lumbar;
thoracolumbar) 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
© 2012 Pearson Education, Inc.
16-1 Divisions of the ANS
• Seven Responses to Increased Sympathetic
Activity
1. Heightened mental alertness
2. Increased metabolic rate
3. Reduced digestive and urinary functions
4. Energy reserves activated
5. Increased respiratory rate and respiratory
passageways dilate
6. Increased heart rate and blood pressure
7. Sweat glands activated
© 2012 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
© 2012 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
© 2012 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
• Roughly 100 million neurons
• All neurotransmitters are found in the brain
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• The Sympathetic Division
• Preganglionic neurons located between segments T1
and L2 of spinal cord
• Ganglionic neurons in ganglia near vertebral column
• Cell bodies of preganglionic neurons in lateral gray
horns
• Axons enter ventral roots of segments
© 2012 Pearson Education, Inc.
Figure 16-3 The Organization of the Sympathetic Division of the ANS
Sympathetic Division of ANS
Ganglionic Neurons
Target Organs
Sympathetic
chain ganglia
(paired)
Visceral effectors
in thoracic cavity,
head, body wall,
and limbs
Collateral
ganglia
(unpaired)
Visceral effectors
in abdominopelvic
cavity
Adrenal
medullae
(paired)
Organs and systems
throughout body
Preganglionic
Neurons
Lateral gray
horns of spinal
segments
T1–L2
KEY
Preganglionic fibers
Postganglionic fibers
Hormones released
into circulation
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Ganglionic Neurons
• Occur in three locations
1. Sympathetic chain ganglia
2. Collateral ganglia
3. Suprarenal medullae
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Chain Ganglia
• Are on both sides of vertebral column
• Control effectors:
• In body wall
• Inside thoracic cavity
• In head
• In limbs
© 2012 Pearson Education, Inc.
Figure 16-4a Sites of Ganglia in Sympathetic Pathways
SYMPATHETIC CHAIN GANGLIA
Spinal nerve
Preganglionic
neuron
Autonomic ganglion of
right sympathetic chain
Autonomic ganglion
of left sympathetic chain
Innervates
visceral
effectors via
spinal nerves
White
ramus
Ganglionic
neuron
Sympathetic nerve
(postganglionic
fibers)
Innervates visceral
organs in thoracic
cavity via
sympathetic nerves
© 2012 Pearson Education, Inc.
Gray ramus
KEY
Preganglionic neurons
Ganglionic neurons
16-2 The Sympathetic Division
• Collateral Ganglia
• Are anterior to vertebral bodies
• Contain ganglionic neurons that innervate tissues and
organs in abdominopelvic cavity
© 2012 Pearson Education, Inc.
Figure 16-4b Sites of Ganglia in Sympathetic Pathways
COLLATERAL GANGLIA
Lateral
gray
horn
White
ramus
Splanchnic
nerve
(preganglionic
fibers)
Postganglionic
fibers
KEY
Preganglionic neurons
Ganglionic neurons
© 2012 Pearson Education, Inc.
Collateral
ganglion
Innervates
visceral organs in
abdominopelvic
cavity
16-2 The Sympathetic Division
• Adrenal Medullae (Suprarenal Medullae)
• Very short axons
• When stimulated, release neurotransmitters into
bloodstream (not at synapse)
• Function as hormones to affect target cells throughout
body
© 2012 Pearson Education, Inc.
Figure 16-4c Sites of Ganglia in Sympathetic Pathways
THE ADRENAL MEDULLAE
Preganglionic fibers
Endocrine cells
(specialized ganglionic
neurons)
Adrenal
medullae
KEY
Preganglionic neurons
Ganglionic neurons
© 2012 Pearson Education, Inc.
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
© 2012 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
• Give rise to myelinated white ramus
• Carry myelinated preganglionic fibers into sympathetic
chain ganglion
• May synapse at collateral ganglia or in adrenal
medullae
© 2012 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)
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Chain Ganglia
• Postganglionic Fibers
• Paths of unmyelinated postganglionic fibers
depend on targets
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Chain Ganglia
• Postganglionic fibers control visceral effectors
• In body wall, head, neck, or limbs
• Enter gray ramus
• Return to spinal nerve for distribution
• Postganglionic fibers innervate effectors
• Sweat glands of skin
• Smooth muscles in superficial blood vessels
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Chain Ganglia
• Postganglionic fibers innervating structures in thoracic
cavity form bundles
• Sympathetic nerves
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Chain Ganglia
• Each sympathetic chain ganglia contains:
• 3 cervical ganglia
• 10–12 thoracic ganglia
• 4–5 lumbar ganglia
• 4–5 sacral ganglia
• 1 coccygeal ganglion
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Chain Ganglia
• 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
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Chain Ganglia
• Chain ganglia provide postganglionic fibers
• Through gray rami (unmyelinated postganglionic
fibers)
• To cervical, lumbar, and sacral spinal nerves
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Chain Ganglia
• Only spinal nerves T1–L2 have white rami
• Every spinal nerve has gray ramus
• That carries sympathetic postganglionic fibers for
distribution in body wall
© 2012 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
© 2012 Pearson Education, Inc.
Figure 16-5 The Distribution of Sympathetic Innervation
PONS
Superior
Cervical
sympathetic
ganglia
Middle
Inferior
T1
Gray rami to
spinal nerves
KEY
Preganglionic neurons
Ganglionic neurons
© 2012 Pearson Education, Inc.
T1
Figure 16-5 The Distribution of Sympathetic Innervation
Eye
PONS
Salivary
glands
Sympathetic nerves
Heart
Cardiac and
pulmonary plexuses
(see Figure 16-10)
T1
KEY
Preganglionic neurons
Ganglionic neurons
© 2012 Pearson Education, Inc.
Lung
Figure 16-5 The Distribution of Sympathetic Innervation
T1
Greater
splanchnic
nerve
KEY
Preganglionic neurons
Ganglionic neurons
Celiac ganglion
Superior
mesenteric
ganglion
Liver and
gallbladder
Stomach
Splanchnic
nerves
Spleen
Pancreas
Inferior
mesenteric
ganglion
L2
Large
intestine
Small
intestine
Adrenal
medulla
Kidney
Coccygeal
ganglia (Co1)
fused together
© 2012 Pearson Education, Inc.
Uterus Ovary
Penis Scrotum Urinary bladder
Figure 16-5 The Distribution of Sympathetic Innervation
Postganglionic fibers
to spinal nerves
(innervating skin,
blood vessels,
sweat glands,
arrector pili muscles,
adipose tissue)
Sympathetic
chain ganglia
L2
Spinal cord
KEY
Preganglionic neurons
Ganglionic neurons
© 2012 Pearson Education, Inc.
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
• Originate as paired ganglia (left and right)
• Usually fuse together in adults
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Collateral Ganglia
• Postganglionic fibers
• Leave collateral ganglia
• Extend throughout abdominopelvic cavity
• 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
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Collateral Ganglia
• Preganglionic fibers from seven inferior thoracic
segments
• End at celiac ganglion or superior mesenteric
ganglion
• Ganglia embedded in network of autonomic nerves
• Preganglionic fibers from lumbar segments
• Form splanchnic nerves
• End at inferior mesenteric ganglion
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Collateral Ganglia
• Celiac ganglion
• Pair of interconnected masses of gray matter
• May form single mass or many interwoven masses
• Postganglionic fibers innervate stomach, liver,
gallbladder, pancreas, and spleen
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Collateral Ganglia
• Superior mesenteric ganglion
• Near base of superior mesenteric artery
• Postganglionic fibers innervate small intestine and
proximal 2/3 of large intestine
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Collateral Ganglia
• Inferior mesenteric ganglion
• Near base of inferior mesenteric artery
• Postganglionic fibers provide sympathetic innervation to
portions of:
• Large intestine
• Kidney
• Urinary bladder
• Sex organs
© 2012 Pearson Education, Inc.
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
© 2012 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% of secretory output
• Remaining is norepinephrine (NE)
• Noradrenaline
© 2012 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
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Activation
• Change activities of tissues and organs by:
• Releasing NE at peripheral synapses
• Target specific effectors, smooth muscle fibers in
blood vessels of skin
• Are activated in reflexes
• Do not involve other visceral effectors
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Sympathetic Activation
• Changes activities of tissues and organs by:
• Distributing E and NE throughout body in bloodstream
• Entire division responds (sympathetic activation)
• Are controlled by sympathetic centers in
hypothalamus
• Effects are not limited to peripheral tissues
• Alters CNS activity
© 2012 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
© 2012 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 at specific target organs
© 2012 Pearson Education, Inc.
16-3 Various Sympathetic Neurotransmitters
• Ganglionic Neurons
• Axon terminals
• Form branching networks of telodendria instead of synaptic
terminals
• Telodendria form sympathetic varicosities
• Resemble string of pearls
• Swollen segment packed with neurotransmitter vesicles
• Pass along or near surface of effector cells
• No specialized postsynaptic membranes
• Membrane receptors on surfaces of target cells
© 2012 Pearson Education, Inc.
Figure 16-6 Sympathetic Varicosities
Preganglionic fiber
(myelinated)
Ganglionic
neuron
Ganglion
Postganglionic fiber
(unmyelinated)
Varicosities
Vesicles containing
norepinephrine
Mitochondrion
Schwann cell
cytoplasm
5 m
Smooth muscle cells
© 2012 Pearson Education, Inc.
Varicosities
16-3 Various Sympathetic Neurotransmitters
• Ganglionic Neurons
• Axon terminals
• Release NE at most varicosities
• Called adrenergic neuron
• Some ganglionic neurons release ACh instead
• Are located in body wall, skin, brain, and skeletal
muscles
• Called cholinergic neurons
© 2012 Pearson Education, Inc.
16-3 Various Sympathetic Neurotransmitters
• Sympathetic Stimulation and the Release of NE
and E
•
Primarily from interactions of NE and E with two
types of adrenergic membrane receptors
1. Alpha receptors (NE more potent)
2. Beta receptors
•
Activates enzymes on inside of cell membrane via G
proteins
© 2012 Pearson Education, Inc.
16-3 Various Sympathetic Neurotransmitters
• Sympathetic Stimulation and the Release of NE
and E
• Alpha-1 (1)
• More common type of alpha receptor
• Releases intracellular calcium ions from reserves
in endoplasmic reticulum
• Has excitatory effect on target cell
© 2012 Pearson Education, Inc.
16-3 Various Sympathetic Neurotransmitters
• Sympathetic Stimulation and the Release of NE
and E
• Alpha-2 (2)
• Lowers cAMP levels in cytoplasm
• Has inhibitory effect on the cell
• Helps coordinate sympathetic and
parasympathetic activities
© 2012 Pearson Education, Inc.
16-3 Various Sympathetic Neurotransmitters
• Sympathetic Stimulation and the Release of NE
and E
• Beta () receptors
• Affect membranes in many organs (skeletal muscles,
lungs, heart, and liver)
• Trigger metabolic changes in target cell
• Stimulation increases intracellular cAMP levels
© 2012 Pearson Education, Inc.
16-3 Various Sympathetic Neurotransmitters
• Three Main Types of Beta Receptors
1. Beta-1 (1)
•
Increases metabolic activity
2. Beta-2 (2)
•
Triggers relaxation of smooth muscles along respiratory tract
3. Beta-3 (3)
•
Leads to lipolysis, the breakdown of triglycerides in
adipocytes
© 2012 Pearson Education, Inc.
16-3 Various Sympathetic Neurotransmitters
• Sympathetic Stimulation and the Release of ACh
and NO
• 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
© 2012 Pearson Education, Inc.
16-3 Various Sympathetic Neurotransmitters
• Sympathetic Stimulation and the Release of ACh
and 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
© 2012 Pearson Education, Inc.
16-4 The Parasympathetic Division
• Autonomic Nuclei
• 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
© 2012 Pearson Education, Inc.
16-4 The Parasympathetic Division
• Ganglionic Neurons in Peripheral Ganglia
• Terminal ganglion
• Near target organ
• Usually paired
• Intramural ganglion
• Embedded in tissues of target organ
• Interconnected masses
• Clusters of ganglion cells
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
Figure 16-7 The Organization of the Parasympathetic Division of the ANS
Parasympathetic Division of ANS
Preganglionic Neurons
Nuclei in
brain stem
Ganglionic Neurons
Target Organs
Ciliary ganglion
Intrinsic eye muscles
(pupil and lens shape)
Pterygopalatine
and submandibular
ganglia
Nasal glands, tear
glands, and salivary
glands
Otic ganglion
Parotid salivary gland
Intramural
ganglia
Visceral organs
of neck,
thoracic cavity,
and most of
abdominal cavity
Intramural
ganglia
Visceral organs in
inferior portion of
abdominopelvic cavity
N III
N VII
N IX
NX
KEY
Preganglionic
fibers
Postganglionic
fibers
© 2012 Pearson Education, Inc.
Nuclei in
spinal cord
segments
S2–S4
Pelvic
nerves
16-4 The Parasympathetic Division
• Oculomotor, Facial, and Glossopharyngeal
Nerves
• Control visceral structures in head
• Synapse in ciliary, pterygopalatine, submandibular,
and otic ganglia
• Short postganglionic fibers continue to their peripheral
targets
© 2012 Pearson Education, Inc.
16-4 The Parasympathetic Division
• Vagus Nerve
• Provides preganglionic parasympathetic innervation to structures
in:
• Neck
• Thoracic and abdominopelvic cavity as distant as a distal
portion of large intestine
• Provides 75% of all parasympathetic outflow
• Branches intermingle with fibers of sympathetic division
© 2012 Pearson Education, Inc.
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, and
the sex organs
© 2012 Pearson Education, Inc.
Figure 16-8 The Distribution of Parasympathetic Innervation
Pterygopalatine ganglion
N III
Lacrimal gland
Eye
Ciliary ganglion
PONS
N VII
N IX
Submandibular
ganglion
Salivary glands
Otic ganglion
N X (Vagus)
Heart
KEY
Preganglionic neurons
Ganglionic neurons
© 2012 Pearson Education, Inc.
Lungs
Figure 16-8 The Distribution of Parasympathetic Innervation
KEY
Preganglionic neurons
Ganglionic neurons
Lungs
Autonomic plexuses
(see Figure 16-10)
Liver and
gallbladder
Stomach
Spleen
Pancreas
Large
intestine
Small
intestine
Rectum
Pelvic
nerves
Spinal
cord
Kidney
S2
S3
S4
Uterus Ovary
© 2012 Pearson Education, Inc.
Penis
Scrotum
Urinary bladder
16-4 The Parasympathetic Division
• Parasympathetic Activation
• Centers on relaxation, food processing, and
energy absorption
• Localized effects, last a few seconds at most
© 2012 Pearson Education, Inc.
16-4 The Parasympathetic Division
• Major Effects of Parasympathetic Division
• Constriction of the pupils
• (To restrict the amount of light that enters the eyes)
• And focusing of the lenses of the eyes on nearby objects
• Secretion by digestive glands
• Including salivary glands, gastric glands, duodenal
glands, intestinal glands, the pancreas (exocrine and
endocrine), and the liver
© 2012 Pearson Education, Inc.
16-4 The Parasympathetic Division
• Major Effects of Parasympathetic Division
• Secretion of hormones
• That 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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
16-5 Parasympathetic Neurons Release ACh
• Neuromuscular and Neuroglandular Junctions
• All release ACh as neurotransmitter
• Small, with narrow synaptic clefts
• Effects of stimulation are short lived
• Inactivated by acetylcholinesterase (AChE) at synapse
• ACh is also inactivated by tissue cholinesterase in
surrounding tissues
© 2012 Pearson Education, Inc.
16-5 Parasympathetic Neurons Release ACh
• Membrane Receptors and Responses
• Nicotinic receptors
• On surfaces of ganglion cells (sympathetic and
parasympathetic)
• Exposure to ACh causes excitation of ganglionic
neuron or muscle fiber
© 2012 Pearson Education, Inc.
16-5 Parasympathetic Neurons Release ACh
• Membrane Receptors and Responses
• Muscarinic receptors
• At cholinergic neuromuscular or neuroglandular
junctions (parasympathetic)
• At few cholinergic junctions (sympathetic)
• G proteins
• Effects are longer lasting than nicotinic receptors
• Response reflects activation or inactivation of
specific enzymes
• Can be excitatory or inhibitory
© 2012 Pearson Education, Inc.
16-5 Parasympathetic Neurons Release ACh
• Dangerous Environmental Toxins
• Produce exaggerated, uncontrolled responses
• Nicotine
• Binds to nicotinic receptors
• Targets autonomic ganglia and skeletal neuromuscular
junctions
• 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
© 2012 Pearson Education, Inc.
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)
© 2012 Pearson Education, Inc.
Table 16-1 Adrenergic and Cholinergic Receptors of the ANS
© 2012 Pearson Education, Inc.
16-6 Dual Innervation
• 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
• Two divisions commonly have opposing effects
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
Figure 16-9 Summary: The Anatomical Differences between the Sympathetic and Parasympathetic Divisions
Sympathetic
CNS
Parasympathetic
Preganglionic
neuron
PNS
Preganglionic
fiber
Sympathetic
ganglion
KEY
Neurotransmitters
Acetylcholine
Norepinephrine
or
Epinephrine
Ganglionic
neurons
Circulatory
system
Postganglionic
fiber
TARGET
© 2012 Pearson Education, Inc.
Parasympathetic
ganglion
Table 16-2 A Structural Comparison of the Sympathetic and Parasympathetic Divisions of the ANS
© 2012 Pearson Education, Inc.
Table 16-3 A Functional Comparison of the Sympathetic and Parasympathetic Divisions of the ANS
© 2012 Pearson Education, Inc.
Table 16-3 A Functional Comparison of the Sympathetic and Parasympathetic Divisions of the ANS
© 2012 Pearson Education, Inc.
Table 16-3 A Functional Comparison of the Sympathetic and Parasympathetic Divisions of the ANS
© 2012 Pearson Education, Inc.
Table 16-3 A Functional Comparison of the Sympathetic and Parasympathetic Divisions of the ANS
© 2012 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
© 2012 Pearson Education, Inc.
16-6 Dual Innervation
• Anatomy of Dual Innervation
•
Cardiac plexus
•
Pulmonary plexus
•
Esophageal plexus
•
Celiac plexus
•
Inferior mesenteric plexus
•
Hypogastric plexus
© 2012 Pearson Education, Inc.
16-6 Dual Innervation
• Cardiac and Pulmonary Plexuses
• Autonomic fibers entering thoracic cavity intersect
• Contain:
• Sympathetic and parasympathetic fibers for heart and
lungs
• Parasympathetic ganglia whose output affects those
organs
© 2012 Pearson Education, Inc.
16-6 Dual Innervation
• Esophageal Plexus
• Contains:
• Descending branches of vagus nerve
• Splanchnic nerves leaving sympathetic chain
• Parasympathetic preganglionic fibers of vagus nerve
enter abdominopelvic cavity with esophagus
• Fibers enter celiac plexus (solar plexus)
© 2012 Pearson Education, Inc.
Figure 16-10 The Autonomic Plexuses and Ganglia
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
© 2012 Pearson Education, Inc.
16-6 Dual Innervation
• Celiac Plexus
• Associated with smaller plexuses, such as inferior
mesenteric plexus
• Innervates viscera within abdominal cavity
© 2012 Pearson Education, Inc.
16-6 Dual Innervation
• Hypogastric Plexus
• Contains:
• Parasympathetic outflow of pelvic nerves
• Sympathetic postganglionic fibers from inferior
mesenteric ganglion
• Splanchnic nerves from sacral sympathetic chain
• Innervates digestive, urinary, and reproductive organs
of pelvic cavity
© 2012 Pearson Education, Inc.
Figure 16-10 The Autonomic Plexuses and Ganglia
Trachea
Left vagus nerve
Thoracic spinal nerves
Esophagus
Splanchnic nerves
Diaphragm
Superior mesenteric artery
Inferior mesenteric artery
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
16-6 Dual Innervation
• Autonomic Tone
• Autonomic motor neurons
• Maintain resting level of spontaneous activity
• Background level of activation determines autonomic
tone
© 2012 Pearson Education, Inc.
16-6 Dual Innervation
• Autonomic Tone
• Significant where dual innervation occurs
• Two divisions have opposing effects
• More important when dual innervation does not
occur
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
16-7 Visceral Reflexes Regulate the ANS
• Somatic Motor Control
• Centers in all portions of CNS
• Lowest level regulatory control
• Lower motor neurons of cranial and spinal visceral reflex arcs
• Highest level
• Pyramidal motor neurons of primary motor cortex
• Operating with feedback from cerebellum and basal nuclei
© 2012 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
© 2012 Pearson Education, Inc.
16-7 Visceral Reflexes Regulate the ANS
• Visceral Reflexes
• Long reflexes
• Autonomic equivalents of polysynaptic reflexes
• Visceral sensory neurons deliver information to CNS
along dorsal roots of spinal nerves
• Within sensory branches of cranial nerves
• Within autonomic nerves that innervate visceral
effectors
• ANS carries motor commands to visceral effectors
• Coordinate activities of entire organ
© 2012 Pearson Education, Inc.
16-7 Visceral Reflexes Regulate the ANS
• Visceral Reflexes
• Short reflexes
• Bypass CNS
• Involve sensory neurons and interneurons located
within autonomic ganglia
• Interneurons synapse on ganglionic neurons
• Motor commands distributed by postganglionic fibers
• Control simple motor responses with localized effects
• One small part of target organ
© 2012 Pearson Education, Inc.
Figure 16-11 Visceral Reflexes
Receptors in
peripheral tissue
Afferent (sensory)
fibers
CENTRAL NERVOUS
SYSTEM
Stimulus
Long
reflex
Short
reflex
Processing center
in spinal cord
(or brain)
Response
Peripheral
effector
Ganglionic
neuron
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
16-7 Visceral Reflexes Regulate the ANS
• Visceral Reflexes
• Enteric nervous system
• Ganglia in the walls of digestive tract contain cell
bodies of:
• Visceral sensory neurons
• Interneurons
• Visceral motor neurons
• Axons form extensive nerve nets
• Control digestive functions independent of CNS
© 2012 Pearson Education, Inc.
Table 16-4 Representative Visceral Reflexes
© 2012 Pearson Education, Inc.
Table 16-4 Representative Visceral Reflexes
© 2012 Pearson Education, Inc.
16-7 Visceral Reflexes Regulate the ANS
• Higher Levels of Autonomic Control
• Simple reflexes from spinal cord provide rapid and automatic
responses
• Complex reflexes coordinated in medulla oblongata
• Contains centers and nuclei involved in:
• Salivation
• Swallowing
• Digestive secretions
• Peristalsis
• Urinary function
• Regulated by hypothalamus
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
Figure 16-12 A Comparison of Somatic and Autonomic Function
Central
Nervous
System
Cerebral cortex
Limbic
system
Thalamus
Hypothalamus
Somatic sensory
Visceral
sensory
Relay and processing centers in brain stem
Long
reflexes
Somatic
reflexes
Peripheral
Nervous
SNS
System
Lower motor
neuron
Sensory
pathways
Preganglionic
neuron
ANS
Short
reflexes
Ganglionic
neuron
Skeletal
muscles
© 2012 Pearson Education, Inc.
Sensory
receptors
Visceral
effectors
Table 16-5 A Comparison of the ANS and SNS
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Higher-Order Functions Share Three Characteristics
1. Require the cerebral cortex
2. Involve conscious and unconscious information processing
3. Are not part of programmed “wiring” of brain
• Can adjust over time
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Memory
• Fact memories
• Are specific bits of information
• Skill memories
• Learned motor behaviors
• Incorporated at unconscious level with repetition
• Programmed behaviors stored in appropriate area
of brain stem
• Complex are stored and involve motor patterns in
the basal nuclei, cerebral cortex, and cerebellum
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Memory
• Short-term memories
• Information that can be recalled immediately
• Contain small bits of information
• Primary memories
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Memory
• Long-term memories
• Memory consolidation – conversion from shortterm to long-term memory
• Two types of long-term memory
1. Secondary memories fade and require effort
to recall
2. Tertiary memories are with you for life
© 2012 Pearson Education, Inc.
Figure 16-13 Memory Storage
Repetition
promotes
retention
Sensory
input
Short-term
Memory
Long-term Memory
Consolidation
Secondary
Memory
Tertiary
Memory
• Cerebral cortex (fact memory)
• Cerebral cortex and cerebellar
cortex (skill memory)
Temporary loss
Permanent loss due
to neural fatigue,
shock, interference
by other stimuli
© 2012 Pearson Education, Inc.
Permanent loss
16-8 Higher-Order Functions
• Brain Regions Involved in Memory Consolidation
and Access
• Amygdaloid body and hippocampus
• Nucleus basalis
• Cerebral cortex
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Amygdaloid Body and Hippocampus
• Are essential to memory consolidation
• Damage may cause:
• Inability to convert short-term memories to new longterm memories
• Existing long-term memories remain intact and
accessible
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Nucleus Basalis
• Cerebral nucleus near diencephalon
• Plays uncertain role in memory storage and retrieval
• Tracts connect with hippocampus, amygdaloid body,
and cerebral cortex
• Damage changes emotional states, memory, and
intellectual functions
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Cerebral Cortex
• Stores long-term memories
• Conscious motor and sensory memories referred to
association areas
• Occipital and temporal lobes
• Special portions crucial to memories of faces, voices, and
words
• A specific neuron may be activated by combination of
sensory stimuli associated with particular individual; called
“grandmother cells”
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Cerebral Cortex
• Visual association area
• Auditory association area
• Speech center
• Frontal lobes
• Related information stored in other locations
• If storage area is damaged, memory will be incomplete
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Cellular Mechanisms of Memory Formation and
Storage
• Involves anatomical and physiological changes in
neurons and synapses
• Increased neurotransmitter release
• Facilitation at synapses
• Formation of additional synaptic connections
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Increased Neurotransmitter Release
• Frequently active synapse increases the amount of
neurotransmitter it stores
• Releases more on each stimulation
• The more neurotransmitter released, the greater
effect on postsynaptic neuron
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Facilitation at Synapses
• Neural circuit repeatedly activated
• Synaptic terminals begin continuously releasing
neurotransmitter
• Neurotransmitter binds to receptors on postsynaptic
membrane
• Produces graded depolarization
• Brings membrane closer to threshold
• Facilitation results affect all neurons in circuit
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Formation of Additional Synaptic Connections
• Neurons repeatedly communicating
• Axon tip branches and forms additional synapses on
postsynaptic neuron
• Presynaptic neuron has greater effect on
transmembrane potential of postsynaptic neuron
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Cellular Mechanisms of Memory Formation and
Storage
• Basis of memory storage
• Processes create anatomical changes
• Facilitate communication along specific neural circuit
• Memory Engram
• Single circuit corresponds to single memory
• Forms as result of experience and repetition
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Cellular Mechanisms of Memory Formation and
Storage
• Efficient conversion of short-term memory
• Takes at least 1 hour
• Repetition crucial
• Factors of conversion
• Nature, intensity, and frequency of original stimulus
• Strong, repeated, and exceedingly pleasant or unpleasant
events likely converted to long-term memories
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Cellular Mechanisms of Memory Formation and
Storage
• Drugs stimulate CNS
• Caffeine and nicotine are examples
• Enhance memory consolidation through facilitation
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Cellular Mechanisms of Memory Formation and
Storage
• Drugs stimulate CNS
• NMDA (N-methyl D-aspartate) Receptors
• Linked to consolidation
• Chemically gated calcium channels
• Activated by neurotransmitter glutamate
• Gates open, calcium enters cell
• Blocking NMDA receptors in hippocampus prevents
long-term memory formation
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• States of Consciousness
• Many gradations of states
• Degree of wakefulness indicates level of ongoing
CNS activity
• When abnormal or depressed, state of wakefulness is
affected
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• States of Consciousness
• Deep sleep
• Also called slow-wave or Non-REM (NREM) sleep
• Entire body relaxes
• Cerebral cortex activity minimal
• Heart rate, blood pressure, respiratory rate, and energy
utilization decline up to 30%
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• States of Consciousness
• Rapid eye movement (REM) sleep
• Active dreaming occurs
• Changes in blood pressure and respiratory rate
• Less receptive to outside stimuli than in deep sleep
• Muscle tone decreases markedly
• Intense inhibition of somatic motor neurons
• Eyes move rapidly as dream events unfold
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• States of Consciousness
• Nighttime sleep pattern
• Alternates between levels
• Begins in deep sleep
• REM periods average 5 minutes in length; increase to
20 minutes over 8 hours
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Sleep
• Has important impact on CNS
• Produces only minor changes in physiological
activities of organs and systems
• Protein synthesis in neurons increases during sleep
• Extended periods without sleep lead to disturbances
in mental function
• 25% of the U.S. population experiences sleep
disorders
© 2012 Pearson Education, Inc.
Figure 16-14a Levels of Sleep
Awake
REM sleep
Deep (slow
wave) sleep
EEG from the awake, REM, and deep (slow wave)
sleep states. The EEG pattern during REM sleep
resembles the alpha waves typical of awake adults.
© 2012 Pearson Education, Inc.
Figure 16-14b Levels of Sleep
Awake
REM sleep
Transition
period
Deep sleep
Time
Typical pattern of sleep stages in a healthy young
adult during a single night’s sleep.
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• States of Consciousness
• Arousal and the reticular activating system (RAS)
• Awakening from sleep
• Function of reticular formation
• Extensive interconnections with sensory, motor,
integrative nuclei, and pathways along brain stem
• Determined by complex interactions between reticular
formation and cerebral cortex
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Reticular Activating System (RAS)
• Important brain stem component
• Diffuse network in reticular formation
• Extends from medulla oblongata to midbrain
• Output of RAS projects to thalamic nuclei that
influence large areas of cerebral cortex
• When RAS inactive, so is cerebral cortex
• Stimulation of RAS produces widespread activation of
cerebral cortex
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Arousal and the Reticular Activating System
• Ending sleep
• Any stimulus activates reticular formation and RAS
• Arousal occurs rapidly
• Effects of single stimulation of RAS last less than a
minute
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Arousal and the Reticular Activating System
• Maintaining consciousness
• Activity in cerebral cortex, basal nuclei, and sensory
and motor pathways continue to stimulate RAS
• After many hours, reticular formation becomes less
responsive to stimulation
• Individual becomes less alert and more lethargic
• Neural fatigue reduces RAS activity
© 2012 Pearson Education, Inc.
16-8 Higher-Order Functions
• Arousal and the Reticular Activating System
• Regulation of sleep–awake cycles
• Involves interplay between brain stem nuclei that use
different neurotransmitters
• Group of nuclei stimulates RAS with NE and maintains
awake, alert state
• Other group promotes deep sleep by depressing RAS
activity with serotonin
• “Dueling” nuclei located in brain stem
© 2012 Pearson Education, Inc.
Figure 16-15 The Reticular Activating System
RAS
Special sensory
input
Reticular
formation
General cranial
or spinal nerve input
© 2012 Pearson Education, Inc.
16-9 Brain Chemistry
• Brain Chemistry
• Changes in normal balance between two or more
neurotransmitters can profoundly affect brain function
© 2012 Pearson Education, Inc.
16-9 Brain Chemistry
• Huntington’s Disease
• Destruction of ACh-secreting and GABA-secreting
neurons in basal nuclei
• Symptoms appear as basal nuclei and frontal lobes
slowly degenerate
• Difficulty controlling movements
• Intellectual abilities gradually decline
© 2012 Pearson Education, Inc.
16-9 Brain Chemistry
• Lysergic Acid Diethylamide (LSD)
• Powerful hallucinogenic drug
• Activates serotonin receptors in brain stem,
hypothalamus, and limbic system
© 2012 Pearson Education, Inc.
16-9 Brain Chemistry
• Serotonin
• Compounds that enhance effects also produce
hallucinations (LSD)
• Compounds that inhibit or block action cause severe
depression and anxiety
• Variations in levels affect sensory interpretation and
emotional states
© 2012 Pearson Education, Inc.
16-9 Brain Chemistry
• Serotonin
• Fluoxetine (Prozac)
• Slows removal of serotonin at synapses
• Increases serotonin concentrations at postsynaptic
membrane
• Classified as selective serotonin reuptake inhibitors
(SSRIs)
• Other SSRIs
• Celexa, Luvox, Paxil, and Zoloft
© 2012 Pearson Education, Inc.
16-9 Brain Chemistry
• Parkinson’s Disease
• Inadequate dopamine production causes motor
problems
• Dopamine
• Secretion stimulated by amphetamines, or “speed”
• Large doses can produce symptoms resembling
schizophrenia
• Important in nuclei that control intentional movements
• Important in other centers of diencephalon and cerebrum
© 2012 Pearson Education, Inc.
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% of people over age 65 have changes in
mental performance and CNS function
© 2012 Pearson Education, Inc.
16-10 Effects of Aging on the Nervous System
• Common Age-related Anatomical Changes in
the Nervous System
• Reduction in Brain Size and Weight
• Reduction in Number of Neurons
• Decrease in Blood Flow to Brain
• Changes in Synaptic Organization of Brain
• Intracellular and Extracellular Changes in CNS Neurons
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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
© 2012 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
© 2012 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
© 2012 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
© 2012 Pearson Education, Inc.
16-10 Effects of Aging on the Nervous System
• Incapacitation
• 85% of elderly population develops changes that
do not interfere with abilities
• Some individuals become incapacitated by
progressive CNS changes
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
16-10 Nervous System Integration
• The Nervous System
• Monitors all other systems
• Issues commands that adjust their activities
• Like conductor of orchestra
© 2012 Pearson Education, Inc.
16-10 Nervous System Integration
• Neural Tissue
• Extremely delicate
• Extracellular environment must maintain homeostatic
limits
• If regulatory mechanisms break down, neurological
disorders appear
© 2012 Pearson Education, Inc.
Figure 16-16 System Integrator: The Nervous System
I N T E G R A T O R
Body System
Provides sensations of touch, pressure,
pain, vibration, and temperature; hair
provides some protection and insulation
for skull and brain; protects peripheral
nerves
Controls contraction of arrector pili
muscles and secrection of sweat glands
Provides calcium 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
Integumentary
Page 165
Nervous System
Skeletal
Page 275
Integumentary
Skeletal
Muscular
Nervous System
Muscular
Page 369
S Y S T E M
Body System
© 2012 Pearson Education, Inc.
Cardiovascular
Page 759
Lymphatic
Page 807
Respiratory
Page 857
Digestive
Page 910
Urinary
Page 992
Reproductive
Page 1072
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
Page 632
The Nervous System