Chapter 11 - Nervous System continued Flashcards

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1
Q

Central nervous system (CNS):

A
  • Consists of brain and spinal cord.
  • Brain is largest and most complex portion of nervous
    system
  • Brain controls sensation, perception, movement, thinking
  • Brain consists of 2 cerebral hemispheres, diencephalon,
    brainstem, cerebellum
  • Brainstem connects the brain to the spinal cord
  • Both brain and spinal cord connect to the peripheral
    nervous system (PNS) by way of peripheral nerves
  • Meninges
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2
Q

Meninges

A

membranes that protect brain and spinal cord;
lie between bone and soft tissues of nervous system

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3
Q

The meninges:
* Membranes that protect brain and spinal cord
* Consist of 3 layers which are…?

A

Dura Mater
Arachnoid Mater
Pia Mater

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4
Q

Dura Mater

A
  • Outer layer
  • Tough, dense connective tissue
  • Dural sinuses
  • Epidural space
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5
Q

Arachnoid mater:

A
  • Middle layer; web-like
  • Subarachnoid space contains cerebrospinal fluid (CSF)
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6
Q

Pia Mater

A
  • Inner layer; attached to surface of brain, spinal cord
  • Contains blood vessels and nerves
  • Nourishes CNS
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7
Q

CSF is produced in 4…

A

ventricles, interconnected cavities
within cerebral hemispheres, and brainstem

-Ventricles are continuous with the central canal of the spinal
cord

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8
Q

what are the 4 Ventricles

A
  • 2 Lateral ventricles (called the first and second ventricles)
  • Third ventricle
  • Fourth ventricle
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9
Q

Interventricular foramina

A

connect third to lateral ventricles

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10
Q

Cerebral aqueduct

A

connects third and fourth ventricles

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11
Q

Cerebrospinal Fluid

A
  • Secreted by the choroid plexuses, special capillaries of
    pia mater covered by ependymal cells
  • Selective transfer of substances from the blood to form
    CSF
  • Nutritive and protective of CNS neurons
  • Helps maintain stable ionic concentrations in the CNS
  • Circulates in ventricles, central canal of spinal cord, and
    subarachnoid space
  • After exchanging substances, CSF is absorbed by the
    arachnoid granulations
  • Volume is about 140 mL at any time
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12
Q

The brain contains centers for/performs the following
functions…?

A
  • Neural centers for sensory function
  • Sensations and perceptions
  • Motor commands to skeletal muscles
  • Higher mental functions, such as memory, reasoning
  • Neural centers for coordinating muscular movement
  • Neural centers for regulating visceral activities
  • Personality
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13
Q

Neural tube gives rise to…?

A

CNS

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14
Q

Brain forms from 3 Vesicles (cavaties)

A
  • Forebrain (prosencephalon)
  • Midbrain (mesencephalon)
  • Hindbrain (rhombencephalon)
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15
Q

3 vesicles facts

A

-Forebrain divides into the telencephalon and diencephalon
-Mesencephalon persists
-Hindbrain divides into metencephalon and myelencephalon
-These 5 cavities persist in mature brain as ventricles and tubes that
connect them:
* Forebrain becomes cerebrum, basal nuclei, and diencephalon
* Mesencephalon remains as midbrain
* Hindbrain becomes cerebellum, pons, and medulla oblongata
10

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16
Q

what are the Major portions of the adult brain

A
  • Cerebrum
  • Diencephalon
  • Cerebellum
  • Brainstem
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17
Q

Cerebrum is the _______ part of the brain

A

Largest

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18
Q

Structures of the Cerebrum

A

Cerebral hemispheres: 2 halves, separated by falx
cerebri
* Corpus callosum: Connects cerebral hemispheres
* Gyri: Ridges or convolutions
* Sulci: Shallow grooves in surface; example: Central
sulcus
* Fissures:
* Deep grooves in surface
* Longitudinal: separates the cerebral hemispheres
* Transverse: separates cerebrum from cerebellum

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19
Q

What are the 5 lobes of the cerebral of hemispheres?

A
  • Frontal lobe
  • Parietal lobe
  • Temporal lobe
  • Occipital lobe
  • Insula (Island of Reil): Deep within lateral sulcus
    4 of the lobes are named for the bones that they underlie
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20
Q

Cerebral Cortex:

A
  • Thin layer of gray matter, which
    makes up outermost layer of all outer
    lobes of the cerebrum
  • Contains almost 75% of neuron cell
    bodies in nervous system
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21
Q

White Matter of Cerebrum:

A
  • Lies under cerebral cortex
  • Makes up most of cerebrum
  • Contains bundles of myelinated axons
    that connect neuron cell bodies in
    cerebral cortex to other portions of
    nervous system
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22
Q

What is the Cerebral Cortex responsible for?

A

Higher Mental Functions

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23
Q

What are the functions of the Cerebral Cortex?

A
  • Interpreting impulses from sensory organs
  • Initiating voluntary movements
  • Storing information as memory
  • Retrieving stored information
  • Reasoning
  • Seat of intelligence and personality

-The cerebral cortex can be divided into sensory, association
and motor areas; some overlap exists

-Each area contains a group of neurons working together to
perform a particular function

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24
Q

Cutaneous sensory area: (sensory)

A
  • Parietal lobe
  • Interprets sensations on skin
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25
Q

Sensory speech area (Wernicke’s area): (sensory)

A
  • Temporal/parietal lobe, usually left hemisphere
  • Understanding and formulating language
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26
Q

Visual area: (sensory)

A

Occipital lobe
* Interprets vision

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27
Q

Auditory area: (sensory)

A
  • Temporal lobe
  • Interprets hearing
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28
Q

Sensory area for taste: (sensory)

A
  • Near base of the central sulcus
  • Includes part of insula
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29
Q

Sensory area for smell: (sensory)

A

Arises from centers deep within temporal lobes

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30
Q

Frontal lobe association areas: (assosiation area of the cortex)

A
  • Concentrating, planning, complex problem solving
  • Emotional behavior, judging consequences of behavior
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31
Q

Parietal lobe association areas: Association Areas of the Cortex

A
  • Understanding speech
  • Choosing words to express thoughts and feelings
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32
Q

Temporal lobe association areas: Association Areas of the Cortex

A
  • Interpret complex sensory experiences (understanding speech,
    reading)
  • Store memories of visual scenes, music, and complex patterns
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33
Q

Occipital lobe association areas: Association Areas of the Cortex

A

Analyze and combine visual images with other sensory experiences

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34
Q

Insula: Association Areas of the Cortex

A

Translating sensory information into proper emotional responses

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35
Q

Primary motor areas (motor cortex): Motor Areas of the Cortex

A
  • Frontal lobes
  • Control voluntary muscles
  • Most nerve fibers cross over in brainstem
36
Q

Broca’s area: Motor Areas of the Cortex

A
  • Frontal lobes
  • Control voluntary muscles
  • Most nerve fibers cross over in brainstem
    Broca’s area:
  • Anterior to primary motor cortex
  • Usually in left hemisphere
  • Controls muscles needed for speech
37
Q

Frontal eye field: Motor Areas of the Cortex

A

Frontal eye field:
* Above Broca’s area
* Controls voluntary movements of eyes and eyelids

38
Q

The ____ hemisphere is dominant in most people

A

LEFT

39
Q

Dominant hemisphere controls:

A
  • Language skills of speech, writing, reading
  • Verbal, analytical, and computational skills
40
Q

Nondominant hemisphere controls

A
  • Nonverbal tasks
  • Motor tasks involving orientation in space
  • Understanding and interpreting musical and visual
    patterns
  • Provides emotional and intuitive thought processes
41
Q

What is the Diencephalon between?

A

cerebral hemispheres and
above the brainstem

42
Q

Diencephalon facts

A

Surrounds the third ventricle
* Composed of gray matter
* Portions of the diencephalon:
* Thalamus
* Hypothalamus
* Optic tracts
* Optic chiasma
* Infundibulum
* Posterior pituitary
* Mammillary bodies
* Pineal gland

43
Q

Diencephalon

Thalamus

A
  • Gateway for sensory impulses ascending to cerebral cortex
  • Receives all sensory impulses (except for sense of smell)
  • Channels impulses to appropriate part of cerebral cortex for interpretation
44
Q

Diencephalon

Hypothalamus

A
  • Maintains homeostasis by regulating visceral activities, such as heart rate,
    blood pressure, body temperature, water and electrolyte balance, hunger,
    body weight, movement and glandular secretion in digestive tract, sleep and
    wakefulness, pituitary gland function
  • Links nervous and endocrine systems
45
Q

Diencephalon

Limbic System

A
  • Consists of several structures in various parts of brain, including diencephalon
  • Controls emotional responses, feelings, behavior oriented toward survival
  • Reacts to potentially life-threatening upsets (physical or psychological)
46
Q

Brainstem

A
  • Connects brain to the spinal cord.
  • Consists of:
  • Midbrain
  • Pons
  • Medulla oblongata
  • Contains nerve fiber tracts and gray matter masses
47
Q

Midbrain

A

Short section of brainstem
* Lies between diencephalon and pons
* Contains bundles of fibers that join lower parts of
brainstem and spinal cord with higher part of brain

48
Q

Midbrain

Cerebral aqueduct:

A

Connects 3rd to 4th ventricle

49
Q

Midbrain

Cerebral peduncles:

A

Main motor pathways that connect
cerebrum to lower portions of nervous system

50
Q

Midbrain

Corpora quadrigemina:

A

Centers for visual and auditory
reflexes

51
Q

Midbrain

Red Nucleus

A

role in postural reflexes

52
Q

Pons

A
  • Rounded bulge on underside of brainstem
  • Between midbrain and medulla oblongata
  • Relays nerve impulses between medulla oblongata and
    cerebrum
  • Relays impulses from cerebrum to cerebellum
  • Helps regulate rhythm of breathing
53
Q

Medulla oblongata:

A
  • 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, swallowing, and vomiting)
  • Injuries are often fatal
54
Q

Reticular Formation:

A
  • Also called Reticular Activating System
  • Complex network of nerve fibers scattered throughout
    brainstem
  • Extends into the diencephalon
  • Connects to centers of hypothalamus, basal nuclei,
    cerebellum, and cerebrum with ascending and descending
    tracts
  • Filters incoming sensory information, passing some to
    cerebral cortex, and discarding unimportant information
  • Arouses cerebral cortex into state of wakefulness
  • Decreased activity causes sleep
55
Q

What are the 2 types of sleep?

A

Non-rapid Eye Movement (Non-REM) Sleep:

Rapid Eye Movement (REM) Sleep:

56
Q

Non-rapid Eye Movement (Non-REM) Sleep:

A
  • Slow wave sleep
  • Person is tired
  • Decreasing activity of reticular formation
  • Restful and dreamless
  • Reduced blood pressure and respiratory rate
  • 3 stages, ranging from light to heavy
  • Alternates with REM sleep
57
Q

Rapid Eye Movement (REM) Sleep:

A
  • Called paradoxical sleep, because some areas of brain are active
  • Heart and respiratory rates irregular
  • Dreaming occurs
58
Q

Sleep is a…?

A

normal, recurring, and reversible state of unconsciousness
characterized in part by limited sensory input and inhibited skeletal muscle
activity

59
Q

Cerebellum

A
  • Inferior to occipital lobes
  • Dorsal to pons and medulla oblongata
  • Two hemispheres separated by falx cerebelli
  • Vermis connects hemispheres
  • Cerebellar cortex (gray matter)
  • Arbor vitae (white matter)
  • Cerebellar peduncles
  • Dentate nucleus (largest nucleus)
  • Integrates sensory information concerning position of body parts
  • Coordinates skeletal muscle activity
  • Maintains posture
  • Recent studies suggest other possible roles for the cerebellum. These include
    interaction with other parts of cerebral cortex, such as the limbic system and
    the auditory areas
60
Q

Spinal Cord:

A
  • Slender column of nervous tissue continuous with brain
    and brainstem
  • Extends downward through vertebral canal
  • Begins at the foramen magnum and terminates at the first
    and second lumbar vertebrae (L1 to L2) space
  • Consists of 31 segments; each gives rise to a pair of
    spinal nerves
  • Spinal nerves are grouped according to the level of the
    vertebra with which they are associated
  • Within each group, the pairs of nerves are numbered in
    sequence from superior to inferior
61
Q

What is the schematic of Reflex Arc?

A

Receptor to Central Nervous System to Effector

62
Q

Monosynaptic (stretch) reflex:

A
  • Contains 2 neurons, sensory and motor
  • Has only 1 synapse in spinal cord
  • Example: Patellar or knee-jerk reflex
  • Helps maintain an upright posture
63
Q

Withdrawal Reflex:

A
  • Occurs when person touches or steps on something painful (stove,
    tack)
  • Prevents or limits tissue damage, by removing limb from painful
    stimulus
  • Polysynaptic: contains sensory neuron, interneuron, motor neuron
  • Reciprocal innervation: flexors contract, extensors are inhibited
64
Q

Crossed Extensor Reflex:

A
  • During withdrawal reflex, flexors on affected (ipsilateral)
    side contract, and extensors are inhibited
  • At same time, extensors on opposite (contralateral) side
    contract, flexors are inhibited
  • Also shifts body weight, so person remains upright
65
Q

Peripheral Nervous System (PNS):

A

Consists of nerves that connect CNS to other body parts;
PNS includes

66
Q

Cranial nerves arise from…

A

the brain

67
Q

Spinal Nerves arise from…

A

the spinal cord

68
Q

Subdivisions of the PNS :

A
  • Somatic nervous system: cranial and spinal nerves that connect
    CNS to the skin and skeletal muscles (conscious activities)
  • Autonomic nervous system: cranial and spinal nerves that
    connect CNS to viscera (subconscious activities)
69
Q

Somatic nervous system:

A

cranial and spinal nerves that connect
CNS to the skin and skeletal muscles (conscious activities)

70
Q

Autonomic nervous system:

A

cranial and spinal nerves that
connect CNS to viscera (subconscious activities)

71
Q

Structure of Peripheral Nerves

A

Nerves are bundles of axons

Nerve “fibers” are axons

72
Q

What are the 3 connective tissue coverings

A

Endoneurium

Perineurium

Epineurium

73
Q

Endoneurium

A

Loose connective tissue that surrounds
individual axons

74
Q

Perineurium

A

Loose connective tissue that surrounds
fascicles

75
Q

Epineurium

A

Dense connective tissue that surrounds a
group of fascicles

76
Q

Nerve Fiber Classification

Classification by Function

A
  • Sensory nerves:
  • Conduct impulses into brain or spinal cord
  • Motor nerves:
  • Conduct impulses to muscles or glands
  • Mixed nerves:
  • Contain both sensory and motor nerve fibers
  • Most nerves are mixed nerves
  • All spinal nerves are mixed nerves (except the first pair
77
Q

Nerve Fiber Classification

Classification by origination:

A
  • Cranial nerves: Originate from brain
  • Spinal nerves: Originate from spinal cord
78
Q

Cranial Nerves:

A
  • 12 pairs on underside of brain
  • Most are mixed nerves
  • Some are sensory, associated with special senses
  • Some are primarily motor, innervate muscles or
    glands
  • Most are attached to the brainstem, with 2
    exceptions
  • First pair has fibers that start in the nasal cavity
  • Second pair originates in eyes, fibers synapse in thalamus
  • Cranial nerves are numbered with Roman numerals
    (I to XII), from anterior to posterior (for the two pairs
    associated with the cerebrum), and from superior to
    inferior (for the remaining pairs)
79
Q

Spinal Nerves

A

All are mixed nerves, except first pair (which is entirely motor)
Originate from spinal cord
31 pairs of spinal nerves:
* 8 cervical nerves, (C1 to C8)
* 12 thoracic nerves (T1 to T12)
* 5 lumbar nerves (L1 to L5)
* 5 sacral nerves (S1 to S5)
* 1 coccygeal nerve (Co)
Cauda equina: Formed by descending roots of lumbar, sacral,
and coccygeal nerves
Dermatome: An area of skin innervated by the sensory nerve
fibers of a particular spinal nerve (in all spinal nerves below C1)

80
Q

Cauda equina:

A

Formed by descending roots of lumbar, sacral,
and coccygeal nerves

81
Q

Dermatome

A

An area of skin innervated by the sensory nerve
fibers of a particular spinal nerve (in all spinal nerves below C1)

82
Q

Autonomic Nervous System (ANS):

A
  • An efferent (motor) part of the peripheral nervous system
    (PNS)
  • Functions without conscious effort
  • Controls visceral activities
  • Regulates smooth muscle, cardiac muscle, and glands
  • Helps maintain homeostasis
  • Helps body respond to stress
  • Prepares body for exercise, intense physical activity
83
Q

what are the 2 divisions of the autonomic nervous system:

A

sympathetic and parasympathetic division

84
Q

Sympathetic division:

A
  • Prepares body for “fight or flight” situations
  • Most active under energy-requiring, stressful, emergency situations
85
Q

Parasympathetic division:

A

Prepares body for “rest and digest” activities
* Most active under resting, non-stressful conditions

Most organs receive input from both divisions

86
Q

Life-Span Changes

A
  • Brain cells begin to die before birth, due to apoptosis, a form of normal
    programmed cell death
  • Over average lifetime, brain shrinks 10%
  • More gray matter than white matter is lost with aging
  • Many cells die in temporal lobes, but few in brainstem
  • By age 90, frontal cortex has lost half its neurons
  • Number of dendritic branches in cerebral cortex decreases
  • Decreased levels of neurotransmitters
  • Action potentials propagation rate declines by 5 to 10%
  • Fading memory
  • Slowed responses and reflexes
  • Increased risk of fainting, falling
  • Changes in sleep patterns that result in fewer sleeping hours