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Chapter 16: Neural Integration II: The Autonomic Nervous System and HigherOrder Functions

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Title: Chapter 16: Neural Integration II: The Autonomic Nervous System and HigherOrder Functions


1
Chapter 16 Neural Integration II The
Autonomic Nervous System and Higher-Order
Functions
2
Somatic Nervous System (SNS)
  • Operates under conscious control
  • Seldom affects long-term survival

3
Autonomic Nervous System (ANS)
  • Operates without conscious instruction
  • Coordinates systems functions
  • cardiovascular
  • respiratory
  • digestive
  • urinary
  • reproductive

4
Organization Similarities of SNS and ANS
Figure 162
5
Organization Similarities of SNS and ANS
  • Are efferent divisions
  • Carry motor commands
  • SNS controls skeletal muscles
  • ANS controls visceral effectors

The Organization of the Somatic and Autonomic
Nervous Systems
PLAY
6
The SNS
Figure 162a
7
The SNS
  • Motor neurons of central nervous system
  • Direct control over skeletal muscles

8
The ANS
Figure 162b
9
The ANS
  • Motor neurons synapse on visceral motor neurons
    in autonomic ganglia
  • Ganglionic neurons control visceral effectors

10
Integrative Centers
  • For autonomic activity in hypothalamus
  • Neurons comparable to upper motor neurons in SNS
  • Visceral Motor Neurons
  • In brain stem and spinal cord, are known as
    preganglionic neurons
  • Part of visceral reflex arcs

11
Preganglionic Fibers
  • Axons of preganglionic neurons
  • Leave CNS and synapse on ganglionic neurons

12
Autonomic Ganglia
  • Peripheral ganglia
  • Contain many ganglionic neurons
  • Ganglionic neurons innervate visceral effectors
  • cardiac muscle
  • smooth muscle
  • glands
  • adipose tissues

13
Postganglionic Fibers
  • Axons of ganglionic neurons
  • Begin at autonomic ganglia
  • extend to peripheral target organs

14
Somatic or Visceral Sensory Information
  • Trigger visceral reflexes
  • Motor commands of reflexes distributed by ANS

15
Motor Commands
  • May control activities of target organs
  • May alter ongoing activity
  • Changes in visceral activity
  • postganglionic fibers release neurotransmitters

16
Sympathetic Division
  • Does not Kick in only during exertion, stress,
    or emergency (common misconception)
  • Some aspects of the system are functioning in
    visceral reflexes for normal activity. (pupil
    dilation and water balance, for instance)

17
Parasympathetic Division
  • Controls during resting conditions
  • Tends to conserve energy
  • Allows for quiet functions (e.g. digestion,
    defecation, etc.)

18
Divisions of the ANS
  • 2 divisions may work independently
  • some structures innervated by only 1 division
  • 2 divisions may work together
  • each controlling one stage of a complex process

19
Sympathetic Division
  • Preganglionic fibers (thoracic and superior
    lumbar) synapse in ganglia near spinal cord
  • Preganglionic fibers are short
  • Postganglionic fibers are long

20
ANS Sympathetic Division
Figure 163
21
Fight or Flight
  • Sympathetic division readies body for crisis
  • Increase in sympathetic activity
  • stimulates tissue metabolism
  • increases alertness

22
7 Responses to Increased Sympathetic Activity
  • Heightened mental alertness
  • Increased metabolic rate
  • Reduced digestive and urinary functions
  • Energy reserves activated
  • Increased respiratory rate and respiratory
    passageways dilate
  • Increased heart rate and blood pressure
  • Sweat glands activated

23
Structure of 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

24
Ganglionic Neurons
  • Occur in 3 locations
  • sympathetic chain ganglia
  • collateral ganglia
  • adrenal medullae

Figure 164
25
Sympathetic Chain Ganglia
  • Are on both sides of vertebral column
  • Control effectors
  • in body wall
  • inside thoracic cavity
  • in head
  • in limbs

26
Sympathetic Chain Ganglia
Figure 164a
27
Collateral Ganglia
  • Are anterior to vertebral bodies
  • Contain ganglionic neurons that innervate tissues
    and organs in abdominopelvic cavity

28
Collateral Ganglia
Figure 164b
29
Parasympathetic Division
  • Preganglionic fibers originate in brain stem and
    sacral segments of spinal cord
  • Synapse in ganglia close to (or within) target
    organs
  • Preganglionic fibers are long
  • Postganglionic fibers are short

30
Rest and Repose
  • Parasympathetic division stimulates visceral
    activity
  • Conserves energy and promotes sedentary activities

31
Pattern of Responses to Increased Levels of
Parasympathetic Activity
  • Decreased
  • metabolic rate
  • heart rate and blood pressure
  • Increased
  • salivary and digestive glands secretion
  • motility and blood flow in digestive tract
  • Urination and defecation stimulation

32
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

33
The Adrenal Medullae
Figure 164c
34
Modified Sympathetic Ganglion
  • At the center of each adrenal gland in area known
    as adrenal medulla
  • Very short axons
  • When stimulated, release neurotransmitters into
    bloodstream (not at synapse)
  • Functions as hormones affect target cells
    throughout body

35
Fibers in Sympathetic Division
  • Preganglionic fibers
  • are relatively short
  • ganglia located near spinal cord
  • Postganglionic fibers
  • are relatively long, except at adrenal medullae
  • Ventral roots of spinal segments T1L2 contain
    sympathetic preganglionic fibers

36
Ventral Roots
  • Give rise to myelinated white ramus
  • Carry myelinated preganglionic fibers into
    sympathetic chain ganglion
  • May synapse at collateral ganglia or in adrenal
    medullae

37
Preganglionic Fibers
  • 1 preganglionic fiber synapses on many ganglionic
    neurons
  • Fibers interconnect sympathetic chain ganglia
  • Each ganglion innervates particular body
    segment(s)

38
Postganglionic Fibers
  • Paths of unmyelinated postganglionic fibers
    depend on targets

39
Sympathetic Innervation
PLAY
The Distribution of Sympathetic Innervation
Figure 165
40
Sympathetic Chain
  • 3 cervical ganglia
  • 1012 thoracic ganglia
  • 45 lumbar ganglia
  • 45 sacral ganglia
  • 1 coccygeal ganglion

41
Preganglionic Neurons
  • Limited to spinal cord segments T1L2
  • white rami (myelinated preganglionic fibers)
  • gray rami (unmyelinated postganglionic fibers)

42
Rami
  • Only spinal nerves T1L2 have white rami
  • Every spinal nerve has gray ramus
  • that carries sympathetic postganglionic fibers
    for distribution in body wall

43
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

44
Abdominopelvic Viscera
  • Receive sympathetic innervation via sympathetic
    preganglionic fibers
  • Synapse in separate collateral ganglia

45
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

46
Postganglionic Fibers
  • Leave collateral ganglia
  • Extend throughout abdominopelvic cavity
  • Innervate variety of visceral tissues and organs

47
Preganglionic Fibers
  • From 7 inferior thoracic segments
  • end at celiac ganglion or superior mesenteric
    ganglion
  • Ganglia embedded in network of autonomic nerves
  • From lumbar segments
  • form splanchnic nerves
  • end at inferior mesenteric ganglion

48
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

49
Superior Mesenteric Ganglion
  • Near base of superior mesenteric artery
  • Postganglionic fibers innervate small intestine
    and proximal 2/3 of large intestine

50
Inferior Mesenteric Ganglion
  • Near base of inferior mesenteric artery
  • Postganglionic fibers provide sympathetic
    innervation to portions of large intestine,
    kidney, urinary bladder, and sex organs

51
Neurotransmitters of the sympathetic division
52
Neuroendocrine Cells of Adrenal Medullae
  • Secrete neurotransmitters epinephrine (E) and
    norepinephrine (NE)
  • Since they are carried in the blood they are
    actually considered hormones

53
Epinephrine
  • Also called adrenaline
  • Is 7580 of secretory output
  • Remaining is noradrenaline (NE)

54
Sympathetic Division
  • Can change activities of tissues and organs by
  • releasing NE at peripheral synapses
  • distributing E and NE throughout body in
    bloodstream

55
Crisis Mode
  • Entire division responds (sympathetic activation)
  • Are controlled by sympathetic centers in
    hypothalamus
  • Effects are not limited to peripheral tissues
  • Alters CNS activity

56
5 Effects of Sympathetic Activation
  • Increased alertness
  • Feelings of energy and euphoria
  • Change in breathing
  • Elevation in muscle tone
  • Mobilization of energy reserves

57
Stimulation of Sympathetic Preganglionic Neurons
  • Releases ACh at synapses with ganglionic neurons
  • Cholinergic Synapses
  • Use ACh as transmitter
  • Excitatory effect on ganglionic neurons

58
Stimulation of Ganglionic Neurons
  • Releases neurotransmitters at specific target
    organs from telodendria
  • Form branching network instead of synaptic knobs

59
Sympathetic Varicosities
  • Resemble string of pearls
  • Packed with neurotransmitter vesicles

Figure 166
60
Chains of Varicosities
  • Formed from postganglionic neurons
  • Pass along or near surface of effector cells
  • No specialized postsynaptic membranes
  • Membrane receptors on surfaces of target cells
  • Release NE

61
Adrenergic Neurons
  • Use NE as neurotransmitter

62
Varicosities and ACh
  • Some ganglionic neurons release ACh instead of NE
  • Are located in body wall, skin, brain, and
    skeletal muscles

63
NE Released by Varicosities
  • Affects targets until reabsorbed or inactivated
  • 5080 of NE is reabsorbed by varicosities
  • is reused or broken down by MAO
  • The rest diffuses out or is broken down by enzymes

64
Duration of Effects on Postsynaptic Membrane
  • NE persist for a few seconds
  • ACh only for 20 msec
  • Effects of NE or E Released by Adrenal Medullae
    Last longer because
  • bloodstream does not contain MAO or COMT
  • most tissues contain low concentrations

65
2 Classes of Sympathetic Receptors
  • Alpha receptors
  • Beta receptors
  • Norepinephrine
  • Stimulates alpha receptors to greater degree than
    beta receptors
  • Epinephrine
  • Stimulates both classes of receptors

66
Localized Sympathetic Activity
  • Involves release of NE at varicosities
  • Primarily affects alpha receptors near active
    varicosities

67
Generalized Sympathetic Activation
  • Release of E by adrenal medulla
  • Affect alpha and beta receptors throughout body

68
Stimulation of Alpha (a) Receptors
  • Activates enzymes on inside of cell membrane
  • Alpha-1 (?1)
  • Alpha-2 (?2)

69
Alpha-1 (?1)
  • More common type of alpha receptor
  • Releases intracellular calcium ions from reserves
    in endoplasmic reticulum
  • Has excitatory effect on target cell

70
Alpha-2 (a2)
  • Lowers cAMP levels in cytoplasm
  • Has inhibitory effect on the cell
  • Helps coordinate sympathetic and parasympathetic
    activities

71
Beta (?) Receptors
  • Affect membranes in many organs (skeletal
    muscles, lungs, heart, and liver)
  • Trigger metabolic changes in target cell
  • Changes occur indirectly
  • Each is a G protein
  • Stimulation increases intracellular cAMP levels

72
Beta Receptors
  • Two types
  • Beta-1 (b1) Increases metabolic activity
  • Beta-2 (b2)
  • Causes inhibition
  • Triggers relaxation of smooth muscles along
    respiratory tract

73
Beta-3 (b3)
  • Found in adipose tissue
  • Leads to lipolysis, the breakdown of
    triglycerides in adipocytes
  • Releases fatty acids into circulation

74
Sympathetic Postganglionic Fibers
  • Mostly adrenergic (release NE)
  • A few cholinergic (release ACh)
  • Innervate sweat glands of skin and blood vessels
    of skeletal muscles and brain
  • Stimulate sweat gland secretion and dilates blood
    vessels

75
ACh
  • Released by parasympathetic division
  • Body wall and skeletal muscles are not innervated
    by parasympathetic division
  • Both NE and ACh needed to regulate visceral
    functions

76
Nitroxidergic Synapses
  • Release nitric oxide (NO) as neurotransmitter
  • Neurons innervate smooth muscles in walls of
    blood vessels in skeletal muscles and the brain
  • Produces vasodilation and increased blood flow

77
Summary of Sympathetic Division (1 of 3)
  • Includes 2 sets of sympathetic chain ganglia, 1
    on each side of vertebral column
  • 3 collateral ganglia anterior to vertebral
    column
  • 2 adrenal medullae
  • Preganglionic fibers are short because ganglia
    are close to spinal cord

78
Summary of Sympathetic Division (2 of 3)
  • Postganglionic fibers are longer and stretch to
    reach target organs
  • Single preganglionic fiber may innervate 2 dozen
    or more ganglionic neurons in different ganglia

79
Summary of Sympathetic Division (3 of 3)
  • Preganglionic neurons release ACh most
    postganglionic fibers release NE, few release ACh
    or NO
  • Effector response depends on second messengers
    activated when NE or E binds to alpha or beta
    receptors

80
ANS The Parasympathetic Division
81
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 S2S4

82
Ganglionic Neurons in Peripheral Ganglia
  • Preganglionic fiber synapses on 68 ganglionic
    neurons
  • terminal ganglion
  • near target organ
  • usually paired
  • intramural ganglion
  • embedded in tissues of target organ
  • interconnected masses
  • clusters of ganglion cells

83
Pattern of Parasympathetic Division
  • All ganglionic neurons in same ganglion
  • Postganglionic fibers influence same target organ
  • Effects of parasympathetic stimulation more
    specific and localized

84
What are the mechanisms of neurotransmitter
release in the parasympathetic division?
85
Parasympathetic Preganglionic Fibers
  • Leave brain as components of cranial nerves
  • III (oculomotor)
  • VII (facial)
  • IX (glossopharyngeal)
  • X (vagus)

86
The Distribution of Parasympathetic Innervation
PLAY
87
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

88
Vagus Nerve
  • Preganglionic parasympathetic innervation to
    structures in
  • neck
  • thoracic and abdominopelvic cavity
  • distal portion of large intestine
  • Provides 75 of all parasympathetic outflow
  • Branches intermingle with fibers of sympathetic
    division

89
Sacral Segments of Spinal Cord
  • Preganglionic fibers carry sacral parasympathetic
    output
  • Do not join ventral roots of spinal nerves

90
Pelvic Nerves
  • Innervate intramural ganglia in walls of
  • kidneys
  • urinary bladder
  • portions of large intestine
  • sex organs

91
Parasympathetic Activation
  • Centers on relaxation, food processing, and
    energy absorption
  • Localized effects, last a few seconds at most

92
10 Effects of Parasympathetic Activation
  • Constriction of pupils
  • restricts light entering eyes
  • Secretion by digestive glands
  • exocrine and endocrine
  • Secretion of hormones
  • Changes in blood flow and glandular activity
  • associated with sexual arousal

93
  • Increases smooth muscle activity
  • along digestive tract
  • Defecation
  • stimulation and coordination
  • Contraction of urinary bladder
  • during urination
  • Constriction of respiratory passageways
  • Reduction in heart rate
  • and force of contraction
  • 10. Sexual arousal
  • stimulation of sexual glandsSexual arousal
  • stimulation of sexual glands

94
Parasympathetic Neurons
  • All release ACh as neurotransmitter
  • Effects vary widely
  • Inactivated by AChE at synapse
  • Ach is also inactivated by pseudocholinesterase
    in surrounding tissues

95
2 Types of ACh Receptors on Postsynaptic
Membranes
  • Nicotinic receptors
  • Muscarinic receptors

96
Nicotinic Receptors
  • On surfaces of ganglion cells (sympathetic and
    parasympathetic)
  • At neuromuscular junctions of somatic nervous
    system

97
Action of Nicotinic Receptors
  • Exposure to ACh causes excitation of ganglionic
    neuron or muscle fiber
  • Open chemically gated channels in postsynaptic
    membrane

98
Muscarinic Receptors
  • At cholinergic neuromuscular or neuroglandular
    junctions (parasympathetic)
  • At few cholinergic junctions (sympathetic)
  • G proteins

99
Action of Muscarinic Receptors
  • Effects are longer lasting than nicotinic
    receptors
  • Response reflects activation or inactivation of
    specific enzymes
  • Can be excitatory or inhibitory

100
Toxins
  • Produce exaggerated, uncontrolled responses
  • Nicotine
  • binds to nicotinic receptors
  • targets autonomic ganglia and skeletal
    neuromuscular junctions
  • Muscarine
  • binds to muscarinic receptors
  • targets parasympathetic neuromuscular or
    neuroglandular junctions

101
Nicotine Poisoning
  • 50 mg ingested or absorbed through skin
  • Symptoms
  • vomiting, diarrhea, high blood pressure, rapid
    heart rate, sweating, profuse salivation,
    convulsions
  • May result in coma or death

102
Muscarine Poisoning
  • Symptoms
  • salivation, nausea, vomiting, diarrhea,
    constriction of respiratory passages, low blood
    pressure, slow heart rate (bradycardia)

103
ANS Adrenergic and Cholinergic Receptors
104
Comparing Sympathetic and Parasympathetic
Divisions
  • Sympathetic
  • widespread impact
  • reaches organs and tissues throughout body
  • Parasympathetic
  • innervates only specific visceral structures

105
Differences between Sympathetic and
Parasympathetic Divisions
Figure 169
106
Summary Sympathetic and Parasympathetic Divisions
Table 16-2
107
Dual Innervation
  • Most vital organs receive instructions from both
    sympathetic and parasympathetic divisions
  • 2 divisions commonly have opposing effects

108
Summary Comparing Sympathetic and
Parasympathetic Divisions
Table 16-3 (1 of 2)
109
Summary Comparing Sympathetic and
Parasympathetic Divisions
Table 16-3 (2 of 2)
110
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

111
Structure 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

112
6 Autonomic Plexuses
  • Cardiac plexus
  • Pulmonary plexus
  • Esophageal plexus
  • Celiac plexus
  • Inferior mesenteric plexus
  • Hypogastric plexus

113
The Autonomic Plexuses
Figure 1610
114
Autonomic Motor Neurons
  • Maintains resting level of spontaneous activity
  • Background level of activation determines
    autonomic tone

115
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

116
Autonomic Tone and Dual Innervation
  • Significant where dual innervation occurs
  • 2 divisions have opposing effects
  • More important when dual innervation does not
    occur

117
Visceral Reflexes
118
ANS
  • Simple reflexes from spinal cord provide rapid
    and automatic responses
  • Complex reflexes coordinated in medulla oblongata

119
Medulla Oblongata
  • Contains centers and nuclei involved in
  • salivation
  • swallowing
  • digestive secretions
  • peristalsis
  • urinary function
  • Regulated by hypothalamus

120
Hypothalamus
  • Interacts with all other portions of brain

121
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

122
Characteristics of Higher-Order Functions
  • Require cerebral cortex
  • Involve conscious and unconscious information
    processing
  • Not part of programmed wiring of brain
  • Can adjust over time

123
Memories
  • Stored bits of information gathered through
    experience
  • Declarative memory
  • Facts
  • Skill Memory
  • Learned motor behaviors
  • Incorporated at unconscious level with repetition
  • Programmed behaviors stored in appropriate area
    of brain stem

124
Short Long Term Memories
  • Short Term
  • Information that can be recalled immediately
  • Contain small bits of information
  • Long Term
  • Can last a life time

125
2 Types of Long-Term Memory
  • Secondary memories fade and require effort to
    recall
  • Tertiary memories are with you for life

126
Long-Term Memories
  • Most stored in cerebral cortex
  • Conscious motor and sensory memories referred to
    association areas

127
Memory Storage
128
Brain Structures and Memory
  • Amygdaloid body and hippocampus
  • are essential to memory consolidation
  • Damage to the Hippocampus
  • Inability to convert short-term memories to new
    long-term memories
  • Existing long-term memories remain intact and
    accessible

129
Occipital and Temporal Lobes
  • Special portions crucial to memories of faces,
    voices, and words
  • Grandmother cells
  • Specific neuron activated by combination of
    sensory stimuli associated with particular
    individual (grandmother)

130
Memories Stored In
  • 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

131
Memory Consolidation at Cellular Level
  • Involves anatomical, physiological changes in
    neurons, synapses

132
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

133
Facilitation at Synapses (1 of 2)
  • Neural circuit repeatedly activated
  • Synaptic terminals begin continuously releasing
    neurotransmitter
  • Neurotransmitter binds to receptors on
    postsynaptic membrane

134
Facilitation at Synapses (2 of 2)
  • Produce graded depolarization
  • Brings membrane closer to threshold
  • Facilitation results affect all neurons in circuit

135
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

136
Memory Engram
  • Single circuit corresponds to single memory
  • Form as result of experience and repetition

137
Factors of Conversion of short to long term memory
  • Nature, intensity, and frequency of original
    stimulus
  • Strong, repeated, and exceedingly pleasant or
    unpleasant events likely converted to long-term
    memories

138
NMDA (N-methyl D-aspartate) Receptors
  • Linked to consolidation
  • Chemically gated calcium channels
  • Activated by neurotransmitter glycine
  • Gates open, calcium enters cell
  • Blocking NMDA receptors in hippocampus prevents
    long-term memory formation

139
States of Consciousness
  • Many gradations of both states
  • Degree of wakefulness indicates level of ongoing
    CNS activity
  • When abnormal or depressed, state of wakefulness
    is affected

140
2 types of Sleep
  • Characteristic patterns of brain wave activity
  • deep sleep
  • REM

Figure 1614a
141
Deep Sleep
  • Also called slow wave sleep
  • Entire body relaxes
  • Cerebral cortex activity minimal
  • Heart rate, blood pressure, respiratory rate, and
    energy utilization decline up to 30

142
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

143
Nighttime Sleep Pattern
144
Significance of Sleep
  • Has important impact on CNS
  • 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

145
Arousal
  • Awakening from sleep
  • Function of reticular formation

146
Reticular Activating System (RAS)
  • Important brain stem component
  • Diffuse network in reticular formation
  • Extends from medulla oblongata to mesencephalon

147
Reticular Activating System (RAS)
Figure 1615
148
Ending Sleep
  • Any stimulus activates reticular formation and
    RAS
  • Arousal occurs rapidly
  • Effects of single stimulation of RAS last less
    than a minute

149
Regulation of AwakeAsleep 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

150
Drugs and Clinical Considerations
151
Lysergic Acid Diethylamide (LSD)
  • Powerful hallucinogenic drug
  • Activates serotonin receptors in brain stem,
    hypothalamus, and limbic system

152
Serotonin
  • Compounds that enhance effects also produce
    hallucinations
  • Compounds that inhibit or block action cause
    severe depression and anxiety
  • Variations in levels affect sensory
    interpretation and emotional states

153
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

154
Parkinsons Disease
  • Inadequate dopamine production causes motor
    problems

155
Huntingtons 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

156
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

157
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

158
Reduction in Brain Size and Weight
  • Decrease in volume of cerebral cortex
  • Narrower gyri and wider sulci
  • Larger subarachnoid space

159
Reduction in Number of Neurons
  • Brain shrinkage linked to loss of cortical
    neurons
  • No neuronal loss in brain stem nuclei

160
Decrease in Blood Flow to Brain
  • Arteriosclerosis
  • fatty deposits in walls of blood vessels
  • reduce blood flow through arteries
  • increase chances of rupture
  • Cerebrovascular accident (CVA), or stroke
  • may damage surrounding neural tissue

161
Intracellular and Extracellular Changes in CNS
Neurons
  • Neurons in brain accumulate abnormal
    intracellular deposits
  • Including lipofuscin and neurofibrillary tangles

162
Incapacitation
  • 85 of elderly population develops changes that
    do not interfere with abilities
  • Some individuals become incapacitated by
    progressive CNS changes

163
Senility
  • Also called senile dementia
  • Degenerative changes
  • memory loss
  • anterograde amnesia
  • emotional disturbances
  • Alzheimers disease is most common

164
Thats it(phew!)
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