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
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The SNS
Figure 162a
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The SNS

• Motor neurons of central nervous system
• Direct control over skeletal muscles

8
The ANS
Figure 162b
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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

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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

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Postganglionic Fibers

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

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Somatic or Visceral Sensory Information

• Trigger visceral reflexes
• Motor commands of reflexes distributed by ANS

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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)

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Parasympathetic Division

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

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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

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Sympathetic Division

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

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ANS Sympathetic Division
Figure 163
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Fight or Flight

• Sympathetic division readies body for crisis
• Increase in sympathetic activity
• stimulates tissue metabolism
• increases alertness

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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

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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

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Ganglionic Neurons

• Occur in 3 locations
• sympathetic chain ganglia
• collateral ganglia
• adrenal medullae

Figure 164
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Sympathetic Chain Ganglia

• Are on both sides of vertebral column
• Control effectors
• in body wall
• inside thoracic cavity
• in head
• in limbs

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Sympathetic Chain Ganglia
Figure 164a
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Collateral Ganglia

• Are anterior to vertebral bodies
• Contain ganglionic neurons that innervate tissues
  and organs in abdominopelvic cavity

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Collateral Ganglia
Figure 164b
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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

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Rest and Repose

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

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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

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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

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The Adrenal Medullae
Figure 164c
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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

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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

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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

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Preganglionic Fibers

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

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Postganglionic Fibers

• Paths of unmyelinated postganglionic fibers
  depend on targets

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Sympathetic Innervation
PLAY
The Distribution of Sympathetic Innervation
Figure 165
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Sympathetic Chain

• 3 cervical ganglia
• 1012 thoracic ganglia
• 45 lumbar ganglia
• 45 sacral ganglia
• 1 coccygeal ganglion

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Preganglionic Neurons

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

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Rami

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

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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

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Abdominopelvic Viscera

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

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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

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Postganglionic Fibers

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

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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

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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

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Superior Mesenteric Ganglion

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

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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

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Neurotransmitters of the sympathetic division
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Neuroendocrine Cells of Adrenal Medullae

• Secrete neurotransmitters epinephrine (E) and
  norepinephrine (NE)
• Since they are carried in the blood they are
  actually considered hormones

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Epinephrine

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

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Sympathetic Division

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

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Crisis Mode

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

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5 Effects of Sympathetic Activation

• Increased alertness
• Feelings of energy and euphoria
• Change in breathing
• Elevation in muscle tone
• Mobilization of energy reserves

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Stimulation of Sympathetic Preganglionic Neurons

• Releases ACh at synapses with ganglionic neurons
• Cholinergic Synapses
• Use ACh as transmitter
• Excitatory effect on ganglionic neurons

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Stimulation of Ganglionic Neurons

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

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Sympathetic Varicosities

• Resemble string of pearls
• Packed with neurotransmitter vesicles

Figure 166
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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

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Adrenergic Neurons

• Use NE as neurotransmitter

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Varicosities and ACh

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

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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

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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

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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

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Localized Sympathetic Activity

• Involves release of NE at varicosities
• Primarily affects alpha receptors near active
  varicosities

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Generalized Sympathetic Activation

• Release of E by adrenal medulla
• Affect alpha and beta receptors throughout body

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Stimulation of Alpha (a) Receptors

• Activates enzymes on inside of cell membrane
• Alpha-1 (?1)
• Alpha-2 (?2)

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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

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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

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Beta Receptors

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

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Beta-3 (b3)

• Found in adipose tissue
• Leads to lipolysis, the breakdown of
  triglycerides in adipocytes
• Releases fatty acids into circulation

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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

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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

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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

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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

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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

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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

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ANS The Parasympathetic Division
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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

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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

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Pattern of Parasympathetic Division

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

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What are the mechanisms of neurotransmitter
release in the parasympathetic division?
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Parasympathetic Preganglionic Fibers

• Leave brain as components of cranial nerves
• III (oculomotor)
• VII (facial)
• IX (glossopharyngeal)
• X (vagus)

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The Distribution of Parasympathetic Innervation
PLAY
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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

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Parasympathetic Activation

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

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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

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• 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

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Parasympathetic Neurons

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

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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

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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)

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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

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Differences between Sympathetic and
Parasympathetic Divisions
Figure 169
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Summary Sympathetic and Parasympathetic Divisions
Table 16-2
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Dual Innervation

• Most vital organs receive instructions from both
  sympathetic and parasympathetic divisions
• 2 divisions commonly have opposing effects

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

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The Autonomic Plexuses
Figure 1610
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Autonomic Motor Neurons

• Maintains resting level of spontaneous activity
• Background level of activation determines
  autonomic tone

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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!)