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Nervous System II

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Nervous System II Divisions of the Nervous System Chapter 11 11-1 – PowerPoint PPT presentation

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Title: Nervous System II


1
Nervous System II
Divisions of the Nervous System
Chapter 11
11-1
2
Membranous Coverings
  • Meninges
  • membranes surrounding CNS
  • protect CNS
  • three layers
  • dura mater outer, tough
  • arachnoid mater middle, weblike
  • pia mater inner, delicate

11-2
3
Meninges of the Spinal Cord
11-3
4
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

11-4
5
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

11-5
6
Spinal Cord Structure
  • extends foramen magnum to 2nd lumbar vertebra

11-6
7
Cross Section of Spinal Cord
11-7
8
Spinal Cord Functions
  • center for spinal reflexes
  • conduit for nerve impulses to and from the brain

11-8
9
Reflex Arcs
Reflexes automatic, subconscious responses to
stimuli
11-9
10
Knee-jerk Reflex
  • helps maintain posture

11-10
11
Withdrawal Reflex
  • protective

11-11
12
Crossed-Extensor Reflex
  • flexor muscles contract
  • flexor muscles on opposite side inhibited
  • extensor muscles on opposite side contract for
    balance

11-12
13
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

11-13
14
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

11-16
15
Structure of Cerebrum
  • corpus callosum
  • connects hemispheres
  • convolutions
  • bumps or gyri
  • sulci
  • grooves
  • longitudinal fissure
  • separates hemispheres
  • transverse fissure
  • separates cerebrum from cerebellum

11-19
16
Lobes of Cerebrum
  • Frontal
  • Parietal
  • Temporal
  • Occipital
  • Insula

11-20
17
Functions of Cerebrum
  • interpretation
  • initiating voluntary movements
  • storing memory
  • retrieving memory
  • reasoning
  • center for intelligence and personality

11-21
18
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
11-22
19
Motor 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

11-23
20
Motor Areas
11-24
21
Sensory 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

11-25
22
Sensory Areas
11-26
23
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

11-27
24
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

11-28
25
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

11-29
26
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

11-30
27
Basal Nuclei
  • masses of gray matter
  • deep within cerebral hemispheres
  • caudate nucleus, putamen, globus pallidus
  • produce dopamine
  • control certain muscular activities

11-31
28
Diencephalon
  • between cerebral hemispheres and brainstem
  • surrounds third ventricle
  • thalamus
  • hypothalamus
  • optic tracts
  • optic chiasm
  • infundibulum
  • posterior pituitary
  • mammillary bodies
  • pineal gland

11-32
29
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

11-33
30
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

11-34
31
Brain Stem
  • Three Parts
  • Midbrain
  • Pons
  • Medulla Oblongata

11-35
32
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

11-36
33
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

11-37
34
Medulla 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)

11-38
35
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

11-39
36
Types 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
37
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

11-41
38
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

11-42
39
Cranial Nerves
11-46
40
Cranial Nerves I and II
  • Olfactory (I)
  • sensory
  • fibers transmit impulses associated with smell
  • Optic (II)
  • sensory
  • fibers transmit impulses associated with vision

11-47
41
Cranial 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

11-48
42
Cranial 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

11-49
43
Cranial 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

11-50
44
Cranial 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

11-51
45
Cranial 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
46
Cranial 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

11-53
47
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)

11-54
48
Dermatome
  • an area of skin that the sensory nerve fibers of
    a particular spinal nerve innervate

11-56
49
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

11-60
50
Sympathetic Division
11-64
51
Parasympathetic Division
11-66
52
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

11-70
53
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

11-71
54
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

11-72
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