1. Chapter 11 Nervous System II
Meninges
membranes surrounding CNS
protect CNS
three layers
dura mater – outer, tough
arachnoid mater - weblike
pia mater – inner, delicate
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2. Meninges of the Spinal Cord
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3. Ventricles interconnected cavities
within cerebral hemispheres and brain stem
continuous with central canal of spinal cord
filled with cerebrospinal fluid (csf)
lateral ventricles
third ventricle
fourth ventricle
cerebral aqueduct
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4. Cerebrospinal Fluid secreted by choroid plexus
circulates in ventricles, central canal of spinal cord, and subarachnoid space
completely surrounds brain and spinal cord
clear liquid
nutritive and protective
helps maintain stable ion concentrations in CNS
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5. Spinal Cord Structure extends foramen magnum to 2nd lumbar vertebra
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6. Cross Section of Spinal Cord
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7. Spinal Cord Functions center for spinal reflexes
conduit for nerve impulses to and from the brain
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8. Reflex Arcs Reflexes – automatic, subconscious responses to stimuli
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9. Crossed-Extensor Reflex
flexor muscles contract
flexor muscles on opposite side inhibited
extensor muscles on opposite side contract for balance
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10. Tracts of the Spinal Cord
Ascending tracts conduct sensory impulses to the brain
Descending tracts conduct motor impulses from the brain to motor neurons reaching muscles and glands
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11. Brain Functions interprets sensations determines perception
stores memory
reasoning
makes decisions
coordinates muscular movements
regulates visceral activities
determines personality
Major Parts
cerebrum
Two cerebral hemispheres
diencephalon
brain stem
cerebellum
two cerebellar hemispheres
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12. Structure of Cerebrum corpus callosum connects hemispheres
convolutions
bumps or gyri
sulci
grooves
longitudinal fissure
separates hemispheres
transverse fissure
separates cerebrum from cerebellum
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13. Lobes of Cerebrum
Frontal
Parietal
Temporal
Occipital
Insula
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14. Functions of Cerebrum interpretation initiating voluntary movements
storing memory
retrieving memory
reasoning
center for intelligence and personality
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15. Functional Regions of Cerebral Cortex
Cerebral Cortex – thin layer of gray matter that constitutes the outermost portion of cerebrum; contains 75% of all neurons in nervous system
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16. Motor Areas Primary Motor Areas Broca’s Area Frontal Eye Field
frontal lobes
control voluntary muscles
Broca’s Area
anterior to primary motor cortex
usually in one hemisphere
controls muscles needed for speech
Frontal Eye Field
above Broca’s area
controls voluntary movements of eyes and eyelids
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17. Motor Areas
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18. Sensory Areas Cutaneous Sensory Area Visual Area Auditory Area
parietal lobe
interprets sensations on skin
Visual Area
occipital lobe
interprets vision
Auditory Area
temporal lobe
interprets hearing
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19. Sensory Areas
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20. Association Areas
regions of cortex that are not primary motor or primary sensory areas
widespread throughout the cerebral cortex
analyze and interpret sensory experiences
provide memory, reasoning, verbalization, judgment, emotions
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21. Association Areas Frontal Lobe Association Areas concentrating
planning
problem solving
judging
Temporal Lobe Association Areas
remember visual scenes
remember music
remember complex patterns
Parietal Lobe Association Areas
understanding speech
using words to express thought
Occipital Lobe Association Areas
combine visual images with other sensory experiences
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22. Hemisphere Dominance
In over 90% of population, left hemisphere is dominant
Nondominant hemisphere controls
nonverbal tasks
motor tasks
understanding and interpreting musical and visual patterns
provides emotional and intuitive thought processes
Dominant hemisphere controls
speech
writing
reading
verbal skills
analytical skills
computational skills
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23. Memory Short Term working memory closed circuit
circuit is stimulated over and over
when impulse flow stops, memory disappears
Long Term
changes structure and function of neurons
enhanced synaptic transmission
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24. Basal Nuclei masses of gray matter deep within cerebral hemispheres
caudate nucleus, putamen, globus pallidus
produce dopamine
control certain muscular activities
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25. Diencephalon between cerebral hemispheres and brainstem
surrounds third ventricle
thalamus
hypothalamus
optic tracts
optic chiasm
infundibulum
posterior pituitary
mammillary bodies
pineal gland
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26. Diencephalon Thalamus
gateway for sensory impulses heading to cerebral cortex
receives all sensory impulses (except smell)
channels impulses to appropriate part of cerebral cortex for interpretation
Hypothalamus
maintains homeostasis by regulating visceral activities
links nervous and endocrine systems
Epithalamus
region above thalamus
involved in regulation of sleep/wake cycle and mood
pineal gland secretes melatonin hormone
Also contains one of choroid plexuses that produce CSF
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27. Limbic System Consists of portions of frontal lobe
portions of temporal lobe
hypothalamus
thalamus
basal nuclei
other deep nuclei
Functions
controls emotions
produces feelings
interpret sensory impulses
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28. Brain Stem
Three Parts
Midbrain
Pons
Medulla Oblongata
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29. Midbrain between diencephalon and pons
contains bundles of fibers that join lower parts of brainstem and spinal cord with higher part of brain
cerebral aqueduct
cerebral peduncles – bundles of nerve fibers
corpora quadrigemina – centers for visual and auditory reflexes
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30. Pons rounded bulge on underside of brainstem
between medulla oblongata and midbrain
helps regulate rate and depth of breathing
relays nerve impulses to and from medulla oblongata and cerebellum
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31. Medulla Oblongata enlarged continuation of spinal cord
conduction pathway for ascending and descending impulses between brain and spinal cord
contains autonomic reflex center for cardiac, vasomotor, and respiratory control centers
contains various nonvital reflex control centers (coughing, sneezing, vomiting)
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32. Reticular Formation
complex network of nerve fibers scattered throughout the brain stem
extends into the diencephalon
connects to centers of hypothalamus, basal nuclei, cerebellum, and cerebrum
filters incoming sensory information
arouses cerebral cortex into state of wakefulness
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33. Types of Sleep Slow Wave Rapid Eye Movement (REM) person is tired
decreasing activity of reticular system
restful
dreamless
reduced blood pressure and respiratory rate
ranges from light to heavy
alternates with REM sleep
Rapid Eye Movement (REM)
some areas of brain active
heart and respiratory rates irregular
dreaming occurs
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34. Cerebellum inferior to occipital lobes
posterior to pons and medulla oblongata
two hemispheres
vermis connects hemispheres
cerebellar cortex – gray matter
arbor vitae – white matter
cerebellar peduncles – nerve fiber tracts
dentate nucleus – largest nucleus in cerebellum
integrates sensory information concerning position of body parts
coordinates skeletal muscle activity
maintains posture
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35. Peripheral Nervous System
Cranial nerves arising from the brain
Somatic fibers connecting to the skin and skeletal muscles
Autonomic fibers connecting to viscera
Spinal nerves arising from the spinal cord
Somatic fibers connecting to the skin and skeletal muscles
Autonomic fibers connecting to viscera
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36. Structure of a Peripheral Nerve
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37. Nerve Fiber Classification
Sensory Nerves – conduct impulses into CNS
Motor Nerves – conduct impulses to muscles or glands
Mixed Nerves – contain both sensory nerve fibers and motor nerve fibers; most nerves
General somatic afferent fibers
carry sensory impulses to CNS from skin and skeletal muscles
General somatic efferent fibers
carry motor impulses from CNS to skeletal muscles
General visceral efferent fibers
carry motor impulses away from CNS to smooth muscles and glands
General visceral afferent fibers
carry sensory impulses to CNS from blood vessels and internal organs
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38. Nerve Fiber Classification
Special somatic efferent fibers
carry motor impulses from brain to muscles used in chewing, swallowing, speaking, and forming facial expressions
Special visceral afferent fibers
carry sensory impulses to brain from olfactory and taste receptors
Special somatic afferent fibers
carry sensory impulses to brain from receptors of sight, hearing, and equilibrium
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39. Cranial Nerves
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40. Cranial Nerves Designated by Roman numerals:
I. Olfactory = sense of smell; sensory only.
II. Optic = sense of vision; sensory only.
III. Oculomotor = innervates eye muscles; motor only.
IV. Trochlear = innervates eye muscles; motor only.
V. Trigeminal = largest; sensory from face; motor to chewing muscles; mixed.
VI. Abducens = innervates eye muscles; motor only.
VII. Facial = innervates muscles of facial expression; sensory taste; mixed.
VIII Vestibulocochlear = sense of hearing and equilibrium; sensory only.
IX. Glossopharyngeal = moves tongue and pharynx muscles; mixed.
X Vagus = innervates visceral smooth muscle; mixed.
XI. Accessory = innervates neck muscles; motor only.
XII. Hypoglossal = moves tongue; motor only.
Memorize by using one of many mnemonic devices:
One example is: Oh, Oh, Oh, To Touch And Feel Very Good Velvet AH!"

41. Spinal Nerves mixed nerves 31 pairs 8 cervical (C1 to C8)
12 thoracic (T1 to T12)
5 lumbar (L1 to L5)
5 sacral (S1 to S5)
1 coccygeal (Co)
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42. Spinal Nerves Dorsal root
axons of sensory neurons in the dorsal root ganglion
Dorsal root ganglion
cell bodies of sensory neurons
Ventral root
axons of motor neurons whose cell bodies are in spinal cord
Spinal nerve
union of ventral root and dorsal root

43. Dermatome
an area of skin that the sensory nerve fibers of a particular spinal nerve innervate
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44. Spinal Nerve Plexus
Nerve plexus – complex networks formed by anterior branches of spinal nerves; fibers of various spinal nerves are sorted and recombined
Cervical plexus: neck muscles and diaphragm (breathing)
Brachial plexus: upper limb
Lumbar plexus: anterior and medial thigh
Sacral plexus: posterior lower limb, leg
Each resulting branch of the plexus contains the fibers from several spinal nerves;
Fibers from each spinal nerve are carried to the body periphery via several different routes or branches.
Therefore, damage to one spinal segment cannot completely paralyze any limb muscle.

45. Autonomic Nervous System
functions without conscious effort
controls visceral activities
regulates smooth muscle, cardiac muscle, and glands
efferent fibers typically lead to ganglia outside CNS
Two Divisions
sympathetic – prepares body for fight or flight situations
parasympathetic – prepares body for resting and digesting activities
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46. Autonomic Nerve Fibers
all are motor (efferent)
preganglionic fibers
axons of preganglionic neurons
neuron cell bodies in CNS
postganglionic fibers
axons of postganglionic neurons
neuron cell bodies in ganglia
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47. Sympathetic Division
thoracolumbar divison – location of preganglionic neurons
preganglionic fibers leave spinal nerves through white rami and enter paravertebral ganglia
paraverterbral ganglia and fibers that connect them make up the sympathetic trunk
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48. Sympathetic Division
postganglionic fibers extend from sympathetic ganglia to visceral organs
postganglionic fibers usually pass through gray rami and return to a spinal nerve before proceeding to an effector
preganglionic fibers to adrenal medulla do not synapse with postganglionic neurons
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49. Sympathetic Division
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50. Parasympathetic Division
craniosacral division – location of preganglionic neurons
preganglionic fibers of the head in III, VII, and IX
ganglia are near or within various organs
preganglionic fibers of thorax and abdomen in X
short postganlionic fibers
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51. Parasympathetic Division
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52. Actions of Autonomic Neurotransmitters
depend on receptor
Cholinergic receptors
bind to acetlycholine
muscarinic
excitatory
nicotinic
Adrenergic Receptors
bind to norepinephrine
alpha
different responses on various effectors
beta
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53. Control of Autonomic Activity
Controlled largely by CNS
Medulla oblongata regulates cardiac, vasomotor and respiratory activities
Hypothalamus regulates visceral functions
Limbic system and cerebral cortex control emotional responses
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54. Life-Span Changes Brain cells begin to die before birth
Over average lifetime, brain shrinks 10%
Most cell death occurs in temporal lobes
By age 90, frontal lobe has lost half its neurons
Number of dendritic branches decreases
Decreased levels of neurotransmitters
Fading memory
Slowed responses and reflexes
Changes increase risk of falling
Sleep problems common
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55. Clinical Application Cerebral Injuries and Abnormalities Concussion
brain jarred against cranium
loss of consciousness
temporary loss of memory
mental cloudiness
headache
recovery usually complete
Cerebral Palsy
motor impairment at birth
caused by blocked cerebral blood vessels during development
seizues
learning disabilities
Cerebrovascular Accident
stroke
sudden interruption in blood flow
brain tissues die
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