Title: Nervous%20System%20II
1Nervous System II
Divisions of the Nervous System
Chapter 11
11-1
2Membranous Coverings
- Meninges
- membranes surrounding CNS
- protect CNS
- three layers
- dura mater outer, tough
- arachnoid mater middle, weblike
- pia mater inner, delicate
11-2
3Meninges of the Spinal Cord
11-3
4Ventricles
- 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
11-4
5Cerebrospinal 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
11-5
6Spinal Cord Structure
- extends foramen magnum to 2nd lumbar vertebra
11-6
7Cross Section of Spinal Cord
11-7
8Spinal Cord Functions
- center for spinal reflexes
- conduit for nerve impulses to and from the brain
11-8
9Reflex Arcs
Reflexes automatic, subconscious responses to
stimuli
11-9
10Knee-jerk Reflex
11-10
11Withdrawal Reflex
11-11
12Crossed-Extensor Reflex
- flexor muscles contract
- flexor muscles on opposite side inhibited
- extensor muscles on opposite side contract for
balance
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13Tracts 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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14Brain
- 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
11-16
15Structure of Cerebrum
- corpus callosum
- connects hemispheres
- convolutions
- bumps or gyri
- sulci
- grooves
- longitudinal fissure
- separates hemispheres
- transverse fissure
- separates cerebrum from cerebellum
11-19
16Lobes of Cerebrum
- Frontal
- Parietal
- Temporal
- Occipital
- Insula
11-20
17Functions of Cerebrum
- interpretation
- initiating voluntary movements
- storing memory
- retrieving memory
- reasoning
- center for intelligence and personality
11-21
18Functional 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
11-22
19Motor Areas
- Primary Motor Areas (red)
- frontal lobes
- control voluntary muscles
- Brocas Area (purple)
- anterior to primary motor cortex
- usually in one hemisphere
- controls muscles needed for speech
- Frontal Eye Field
- above Brocas area
- controls voluntary movements of eyes and eyelids
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20Motor Areas
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21Sensory Areas
- Cutaneous Sensory Area (yellow)
- parietal lobe
- interprets sensations on skin
- Visual Area (blue)
- occipital lobe
- interprets vision
- Auditory Area (purple)
- temporal lobe
- interprets hearing
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22Sensory Areas
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23Association 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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24Association 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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25Hemisphere 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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26Memory
- 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
11-30
27Basal Nuclei
- masses of gray matter
- deep within cerebral hemispheres
- caudate nucleus, putamen, globus pallidus
- produce dopamine
- control certain muscular activities
11-31
28Diencephalon
- 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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29Diencephalon
- 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
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30Limbic 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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31Brain Stem
- Three Parts
- Midbrain
- Pons
- Medulla Oblongata
11-35
32Midbrain
- 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
11-36
33Pons
- 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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34Medulla Oblongata
- enlarged continuation of spinal cord
- conducts ascending and descending impulses
between brain and spinal cord - contains cardiac, vasomotor, and respiratory
control centers - contains various nonvital reflex control centers
(coughing, sneezing, vomiting)
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35Reticular 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
11-39
36Types of Sleep
- Slow Wave
- 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
11-40
37Cerebellum
- 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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38Peripheral 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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39Cranial Nerves
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40Cranial Nerves I and II
- Olfactory (I)
- sensory
- fibers transmit impulses associated with smell
- Optic (II)
- sensory
- fibers transmit impulses associated with vision
11-47
41Cranial Nerves III and IV
- Trochlear (IV)
- primarily motor
- motor impulses to muscles that move the eyes
- Oculomotor (III)
- primarily motor
- motor impulses to muscles that
- raise eyelids
- move the eyes
- focus lens
- adjust light entering eye
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42Cranial Nerve V
- Trigeminal (V)
- mixed
- opthalmic division
- sensory from surface of eyes, tear glands,
scalp, forehead, and upper eyelids - maxillary division
- sensory from upper teeth, upper gum, upper lip,
palate, and skin of face - mandibular division
- sensory from scalp, skin of jaw, lower teeth,
lower gum, and lower lip - motor to muscles of mastication and muscles in
floor of mouth
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43Cranial Nerves VI and VII
- Abducens (VI)
- primarily motor
- motor impulses to muscles that move the eyes
- Facial (VII)
- mixed
- sensory from taste receptors
- motor to muscles of facial expression, tear
glands, and salivary glands
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44Cranial Nerves VIII and IX
- Glossopharyngeal (IX)
- mixed
- sensory from pharynx, tonsils, tongue, and
carotid arteries - motor to salivary glands and muscles of pharynx
- Vestibulocochlear (VIII)
- sensory
- sensory from equilibrium receptors of ear
- sensory from hearing receptors
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45Cranial Nerve X
- Vagus (X)
- mixed
- somatic motor to muscles of speech and
swallowing - autonomic motor to viscera of thorax and abdomen
- sensory from pharynx, larynx, esophagus, and
viscera of thorax and abdomen
11-52
46Cranial Nerves XI and XII
- Accessory (XI)
- primarily motor
- motor to muscles of soft palate, pharynx,
larynx, neck, and back
- Hypoglossal (XII)
- primarily motor
- motor to muscles of the tongue
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47Spinal 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)
11-54
48Dermatome
- an area of skin that the sensory nerve fibers of
a particular spinal nerve innervate
11-56
49Autonomic 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
11-60
50Sympathetic Division
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51Parasympathetic Division
11-66
52Control 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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53Life-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
11-71
54Clinical 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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