Chapter 17: The
Nervous System
and Behavioral
Disorders
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Chapter Objectives
 Components of the nervous system.
 Functions of the regions of the brain.
 How the central nervous system is protected.
 Sympathetic and parasympathetic systems.
 Word parts pertaining to the nervous system.
 Major disorders of the nervous system.
 Major behavioral disorders.
 Common symptoms of neurologic disorders.
 Abbreviations used in neurology.
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Key Terms
Normal Structure and Function
afferent
Carrying toward a given point, such as the sensory neurons and
nerves that carry impulses toward the CNS (root fer means “to carry”)
arachnoid mater
The middle layer of the meninges (from the Greek word for spider,
because this tissue resembles a spider web)
autonomic
nervous system
(ANS)
The division of the nervous system that regulates involuntary activities,
controlling smooth muscles, cardiac muscle, and glands; the visceral
nervous system
axon
The fiber of a neuron that conducts impulses away from the cell body
brain
The nervous tissue contained within the cranium; consists of the
cerebrum, diencephalon, brainstem, and cerebellum (root: encephal/o)
brainstem
The part of the brain that consists of the midbrain, pons, and medulla
oblongata
central nervous
system (CNS)
The brain and spinal cord
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Key Terms
Normal Structure and Function (cont’d)
cerebellum
The posterior portion of the brain dorsal to the pons and medulla;
helps to coordinate movement and to maintain balance and posture
(cerebellum means “little brain”) (root: cerebell/o)
cerebral cortex
The cerebrum's thin surface layer of gray matter (the cortex is the
outer region of an organ) (root: cortic/o)
cerebrum
The large upper portion of the brain; it is divided into two
hemispheres by the longitudinal fissure (root: cerebr/o)
cerebrospinal fluid
(CSF)
The watery fluid that circulates in and around the brain and spinal
cord as a protection
cranial nerves
The 12 pairs of nerves that are connected to the brain
dendrite
A fiber of a neuron that conducts impulses toward the cell body
diencephalons
The part of the brain that contains the thalamus, hypothalamus, and
pituitary gland; located between the cerebrum and the brainstem
dura mater
The strong, fibrous outermost layer of the meninges
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Key Terms
Normal Structure and Function (cont’d)
efferent
Carrying away from a given point, such as the motor neurons and
nerves that carry impulses away from the CNS (root fer means “to
carry”)
ganglion
A collection of nerve cell bodies outside the CNS (plural: ganglia) (root:
gangli/o, ganglion/o)
gray matter
Unmyelinated tissue of the nervous system
gyrus
A raised convolution of the surface of the cerebrum (plural: gyri)
hypothalamus
The part of the brain that controls the pituitary gland and maintains
homeostasis
interneuron
Any neuron located between a sensory and a motor neuron in a neural
pathway, such as the neurons that transmit impulses within the CNS
medulla oblongata
The portion of the brain that connects with the spinal cord. It has vital
centers for control of respiration, heart rate, and blood pressure (root:
medull/o). Often called simply medulla
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Key Terms
Normal Structure and Function (cont’d)
meninges
The three membranes that cover the brain and spinal cord (singular:
meninx) (root: mening/o, meninge/o)
midbrain
The part of the brainstem between the diencephalon and the pons;
contains centers for coordination of reflexes for vision and hearing
motor
Producing movement; describes neurons that carry impulses away
from the CNS
myelin
A whitish, fatty substance that surrounds certain axons of the nervous
system
neuroglia
The supportive cells of the nervous system; also called glial cells (from
glia meaning “glue”; root: gli/o)
neuron
The basic unit of the nervous system; a nerve cell
neurotransmitter
A chemical that transmits energy across a synapse. Examples are
epinephrine, acetylcholine (a-sē-til-KŌ-le-n), serotonin (ser-ō-TŌ-nin),
and dopamine (DŌ-pa-me-n)
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Key Terms
Normal Structure and Function (cont’d)
nerve
A bundle of nerve cell fibers outside the CNS (root: neur/o)
parasympathetic
nervous system
The part of the automatic nervous system that reverses the response
to stress and restores homeostasis. It slows heart rate and respiration
rate and stimulates activity of the digestive, urinary, and reproductive
systems.
peripheral nervous
system (PNS)
The portion of the nervous system outside the CNS
pia mater
The innermost layer of the meninges
pons
A rounded area on the ventral surface of the brainstem; contains
fibers that connect regions of the brain; adjective: pontine (PON-ten)
reflex
A simple, rapid, and automatic response to a stimulus
root
A branch of a spinal nerve that connects with the spinal cord; the
dorsal (posterior) root joins the dorsal gray horn of the spinal cord; the
ventral (anterior) root joins the ventral gray horn of the spinal cord
(root: radicul/o)
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Key Terms
Normal Structure and Function (cont’d)
sensory
Describing neurons that carry impulses toward the CNS
somatic nervous
system
The division of the nervous system that controls skeletal (voluntary)
muscles
spinal cord
The nervous tissue contained within the spinal column; extends from
the medulla oblongata to the second lumbar vertebra (root: myel/o)
spinal nerves
The 31 pairs of nerves that connect with the spinal cord
sulcus
A shallow furrow or groove, as on the surface of the cerebrum (plural:
sulci)
sympathetic
nervous system
The part of the autonomic nervous system that mobilizes a response
to stress; increases heart rate and respiration rate and delivers more
blood to skeletal muscles
synapse
The junction between two neurons; also the junction between a motor
neuron and a muscle or gland
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Key Terms
Normal Structure and Function (cont’d)
thalamus
The part of the brain that receives all sensory impulses, except those
for the sense of smell, and directs them to the proper portion of the
cerebral cortex (root: thalam/o)
tract
A bundle of nerve cell fibers within the CNS
ventricle
A small cavity, such as one of the cavities in the brain in which CSF is
produced (root: ventricul/o)
visceral nervous
system
The autonomic nervous system
white matter
Myelinated tissue of the nervous system
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Key Terms
Neurologic Disorders
Alzheimer disease
(AD)
A form of dementia caused by atrophy of the cerebral cortex;
presenile dementia
amyloid
A starchlike substance of unknown composition that accumulates in
the brain in Alzheimer and other diseases
aneurysm
A localized abnormal dilation of a blood vessel that results from
weakness of the vessel wall; an aneurysm may eventually burst
aphasia
Specifically, loss or defect in speech communication (from Greek
phasis, meaning “speech”). In practice, the term is applied more
broadly to a range of language disorders, both spoken and written.
May affect ability to understand speech (receptive aphasia) or the
ability to produce speech (expressive aphasia). Both forms are
combined in global aphasia
astrocytoma
A neuroglial tumor composed of astrocytes
cerebral contusion
A bruise to the surface of the brain following a blow to the head
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Key Terms
Neurologic Disorders (cont’d)
cerebrovascular
accident (CVA)
Sudden damage to the brain resulting from reduction of cerebral
blood flow; possible causes are atherosclerosis, thrombosis, or a
ruptured aneurysm; commonly called stroke
coma
State of deep unconsciousness from which one cannot be roused
concussion
Injury resulting from a violent blow or shock; a concussion of the
brain usually results in loss of consciousness
confusion
A state of reduced comprehension, coherence, and reasoning ability
resulting in inappropriate responses to environmental stimuli
contrecoup injury
Damage to the brain on the side opposite the point of a blow as a
result of the brain's hitting the skull (from French, meaning
“counterblow”)
convulsion
A series of violent, involuntary muscle contractions. A tonic convulsion
involves prolonged contraction of the muscles; in a clonic convulsion
there is alternation of contraction and relaxation. Both forms appear
in grand mal epilepsy
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Key Terms
Neurologic Disorders (cont’d)
dementia
A gradual and usually irreversible loss of intellectual function
embolism
Obstruction of a blood vessel by a blood clot or other material carried
in the circulation
encephalitis
Inflammation of the brain
epidural hematoma
Accumulation of blood in the epidural space (between the dura mater
and the skull)
epilepsy
A chronic disease involving periodic sudden bursts of electric activity
from the brain, resulting in seizures
glioma
A tumor of neuroglia cells
hemiparesis
Partial paralysis or weakness of one side of the body
hemiplegia
Paralysis of one side of the body
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Key Terms
Neurologic Disorders (cont’d)
hydrocephalus
Increased accumulation of CSF in or around the brain as a result of
obstruction to flow. May be caused by tumor, inflammation,
hemorrhage, or congenital abnormality
insomnia
Insufficient or nonrestorative sleep despite ample opportunity to sleep
meningioma
Tumor of the meninges
meningitis
Inflammation of the meninges
multi-infarct
dementia (MID)
Dementia caused by chronic cerebral ischemia (lack of blood supply to
the tissues) as a result of multiple small strokes. There is progressive
loss of cognitive function, memory, and judgment as well as altered
motor and sensory function
multiple sclerosis
(MS)
A chronic, progressive disease involving loss of myelin in the CNS
narcolepsy
Brief, uncontrollable episodes of sleep during the day
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Key Terms
Neurologic Disorders (cont’d)
neurilemoma
A tumor of the sheath (neurilemma) of a peripheral nerve;
schwannoma
paralysis
Temporary or permanent loss of function. Flaccid paralysis involves
loss of muscle tone and reflexes and degeneration of muscles.
Spastic paralysis involves excess muscle tone and reflexes but no
degeneration
parkinsonism
A disorder originating in the basal ganglia and characterized by slow
movements, tremor, rigidity, and masklike face. Also called
Parkinson disease
seizure
A sudden attack, as seen in epilepsy. The most common forms of
seizure are tonic–clonic, or grand mal (gran mal) (from French,
meaning “great illness”); absence seizure, or petit mal (pet-E-mal),
meaning “small illness”; and psychomotor seizure
shingles
An acute viral infection that follows nerve pathways causing small
lesions on the skin. Caused by reactivation of the virus that also
causes chickenpox (varicella–zoster virus). Also called herpes
zoster (HER-pēr ZOS-ter)
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Key Terms
Neurologic Disorders (cont’d)
sleep apnea
Brief periods of breathing cessation during sleep
stroke
Sudden interference with blood flow in one or more cerebral vessels
leading to oxygen deprivation and necrosis of brain tissue; caused by
a blood clot in a vessel (ischemic stroke) or rupture of a vessel
(hemorrhagic stroke). Cerebrovascular accident (CVA)
subdural
hematoma
Accumulation of blood beneath the dura mater
thrombosis
Development of a blood clot within a vessel
tremor
A shaking or involuntary movement
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Key Terms
Diagnosis and Treatment
carotid endarterectomy
Surgical removal of the lining of the carotid artery, the large
artery in the neck that supplies blood to the brain
cerebral angiography
Radiographic study of the blood vessels of the brain after
injection of a contrast medium
electroencephalography
(EEG)
Amplification, recording, and interpretation of the brain’s electric
activity
L-dopa
A drug used in the treatment of parkinsonism; levodopa
lumbar puncture
Puncture of the subarachnoid space in the lumbar region of the
spinal cord to remove spinal fluid for diagnosis or to inject
anesthesia; spinal tap
polysomnography
Simultaneous monitoring of a variety of physiologic functions
during sleep to diagnose sleep disorders
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Key Terms
Behavioral Disorders
anxiety
A feeling of fear, worry, uneasiness, or dread
Asperger syndrome
A behavioral condition on a continuum with autism that may
include difficulty with social interactions and understanding, strong
specific interests, and repetitive behaviors
attention-deficit /
hyperactivity disorder
(ADHD)
A condition that begins in childhood and is characterized by
attention problems, easy boredom, impulsive behavior, and
hyperactivity
autism
A disorder of unknown cause consisting of self-absorption, lack of
response to social contact and affection, preoccupations,
stereotyped behavior, and resistance to change (from auto-, “self”
and -ism, “condition of”)
bipolar disorder
A form of depression with episodes of mania (a state of elation);
manic depressive illness
delusion
A false belief inconsistent with knowledge and experience
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Key Terms
Behavioral Disorders (cont’d)
depression
A mental state characterized by profound feelings of sadness,
emptiness, hopelessness, and lack of interest or pleasure in activities
dysthymia
A mild form of depression that usually develops in response to a
serious life event (from dys- and Greek thymos, meaning “mind,
emotion”)
hallucination
A false perception unrelated to reality or external stimuli
mania
A state of elation, which may include agitation, hyperexcitability, or
hyperactivity (adjective: manic)
obsessivecompulsive
disorder (OCD)
A condition associated with recurrent and intrusive thoughts, images,
and repetitive behaviors performed to relieve anxiety
panic disorder
A form of anxiety disorder marked by episodes of intense fear
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Key Terms
Behavioral Disorders (cont’d)
paranoia
A mental state characterized by jealousy, delusions of persecution, or
perceptions of threat or harm
phobia
An extreme, persistent fear of a specific object or situation
posttraumatic
stress disorder
(PTSD)
Persistent emotional disturbances that follow exposure to lifethreatening, catastrophic events, such as trauma, abuse, natural
disasters, and warfare
psychosis
A mental disorder extreme enough to cause gross misperception of
reality with delusions and hallucinations
schizophrenia
A poorly understood group of severe mental disorders with features of
psychosis, delusions, hallucinations, and withdrawn or bizarre behavior
(schizo means “split” and phren means “mind”)
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Supplementary Terms
Normal Structure and Function
acetylcholine
A neurotransmitter; activity involving acetylcholine is described as
cholinergic
basal ganglia
Four masses of gray matter in the cerebrum and upper brainstem that
are involved in movement and coordination
blood–brain barrier
A special membrane between circulating blood and the brain that
prevents certain damaging substances from reaching brain tissue
Broca area
An area in the left frontal lobe of the cerebrum that controls speech
production
circle of Willis
An interconnection (anastomosis) of several arteries supplying the
brain, located at the base of the cerebrum
contralateral
Affecting the opposite side of the body
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Supplementary Terms
Normal Structure and Function (cont’d)
corpus callosum
A large band of connecting fibers between the cerebral hemispheres
dermatome
The area of the skin supplied by a spinal nerve; term also refers to an
instrument used to cut skin for grafting (see Chapter 21)
epinephrine
A neurotransmitter; also called adrenaline; activity involving
epinephrine is described as adrenergic
ipsilateral
On the same side; unilateral
leptomeninges
The pia mater and arachnoid together
nucleus
A collection of nerve cells within the central nervous system
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Supplementary Terms
Normal Structure and Function (cont’d)
plexus
A network, as of nerves or blood vessels
pyramidal tracts
A group of motor tracts involved in fine coordination. Most of the fibers
in these tracts cross in the medulla to the opposite side of the spinal
cord and affect the opposite side of the body. Fibers not included in the
pyramidal tracts are described as extrapyramidal.
reticular activating
system (RAS)
A widespread system in the brain that maintains wakefulness
Schwann cells
Cells that produce the myelin sheath around peripheral axons
Wernicke area
An area in the temporal lobe concerned with speech comprehension
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Supplementary Terms
Symptoms and Conditions
amyotrophic
lateral sclerosis
(ALS)
A disorder marked by muscular weakness, spasticity, and exaggerated
reflexes caused by degeneration of motor neurons; Lou Gehrig
disease
amnesia
Loss of memory
apraxia
Inability to move with purpose or to use objects properly
ataxia
Lack of muscle coordination; dyssynergia
athetosis
Involuntary, slow, twisting movements in the arms, especially the
hands and fingers
Bell palsy
Paralysis of the facial nerve
berry aneurysm
A small saclike aneurysm of a cerebral artery
catatonia
A phase of schizophrenia in which the patient is unresponsive; there is
a tendency to remain in a fixed position without moving or talking
cerebral palsy
A nonprogressive neuromuscular disorder usually caused by damage
to the CNS near the time of birth. May include spasticity, involuntary
movements, or ataxia
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Supplementary Terms
Symptoms and Conditions (cont’d)
chorea
A nervous condition marked by involuntary twitching of the limbs or
facial muscles
claustrophobia
Fear of being shut in or enclosed (from Latin claudere, “to shut”)
compulsion
A repetitive, stereotyped act performed to relieve tension
Creutzfeldt–Jakob
disease (CJD)
A slow-growing degenerative brain disease caused by a prion (PRĪon), an infectious protein. Related to bovine spongiform
encephalopathy (BSE, “mad cow disease”) in cattle
delirium
A sudden and temporary state of confusion marked by excitement,
physical restlessness, and incoherence
dysarthria
Defect in speech articulation caused by lack of control over the
required muscles
dysmetria
Disturbance in the path or placement of a limb during active
movement. In hypometria, the limb falls short; in hypermetria, the
limb extends beyond the target.
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Supplementary Terms
Symptoms and Conditions (cont’d)
euphoria
An exaggerated feeling of well-being; elation
glioblastoma
A malignant astrocytoma
Guillain–Barré
syndrome
An acute polyneuritis with progressive muscular weakness that usually
occurs after a viral infection; in most cases recovery is complete, but
may take several months to years
hematomyelia
Hemorrhage of blood into the spinal cord, as from an injury
hemiballism
Jerking, twitching movements of one side of the body
Huntington
disease
A hereditary disease of the CNS that usually appears between ages 30
and 50. The patient shows progressive dementia and chorea, and
death occurs within 10 to 15 years.
hypochondriasis
Abnormal anxiety about one's health
ictus
A blow or sudden attack, such as an epileptic seizure
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Supplementary Terms
Symptoms and Conditions (cont’d)
lethargy
A state of sluggishness or stupor
migraine
Chronic intense, throbbing headache that may result from vascular
changes in cerebral arteries. Possible causes include genetic factors,
stress, trauma, and hormonal fluctuations. Headache might be
signaled by visual disturbances, nausea, photophobia, and tingling
sensations
neurofibromatosis
A condition involving multiple tumors of peripheral nerves
neurosis
An emotional disorder caused by unresolved conflicts, with anxiety as
a main characteristic
paraplegia
Paralysis of the legs and lower part of the body
parasomnia
Condition of having undesirable phenomena, such as nightmares,
occur during sleep or become worse during sleep
quadriplegia
Paralysis of all four limbs; tetraplegia
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Supplementary Terms
Symptoms and Conditions (cont’d)
Reye syndrome
A rare acute encephalopathy occurring in children after viral
infections. The liver, kidney, and heart may be involved. Linked to
administration of aspirin during a viral illness
sciatica
Neuritis characterized by severe pain along the sciatic nerve and its
branches
somatoform
disorders
Conditions associated with symptoms of physical disease, such as
pain, hypertension, or chronic fatigue, with no physical basis
somnambulism
Walking or performing other motor functions while asleep and out of
bed; sleepwalking
stupor
A state of unconsciousness or lethargy with loss of responsiveness
syringomyelia
A progressive disease marked by formation of fluid-filled cavities in
the spinal cord
tic
Involuntary, spasmodic, recurrent, and purposeless motor movements
or vocalizations
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Supplementary Terms
Symptoms and Conditions (cont’d)
tic douloureux
Episodes of extreme pain in the area supplied by the trigeminal
nerve; also called trigeminal neuralgia
tabes dorsalis
Destruction of the dorsal (posterior) portion of the spinal cord with
loss of sensation and awareness of body position, as seen in
advanced cases of syphilis
Tourette syndrome
A tic disorder with intermittent motor and vocal manifestations that
begins in childhood. There also may be obsessive and compulsive
behavior, hyperactivity, and distractibility
transient ischemic
attack
A sudden, brief, and temporary cerebral dysfunction usually caused
by interruption of blood flow to the brain
Wallerian
degeneration
Degeneration of a nerve distal to an injury
whiplash
Cervical injury caused by rapid acceleration and deceleration
resulting in damage to muscles, ligaments, disks, and nerves
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Supplementary Terms
Diagnosis and Treatment
Babinski reflex
A spreading of the outer toes and extension of the big toe over the
others when the sole of the foot is stroked. This response is normal in
infants but indicates a lesion of specific motor tracts in adults.
evoked potentials
Record of the electric activity of the brain after sensory stimulation.
Included are visual evoked potentials (VEPs), brainstem auditory
evoked potentials (BAEPs), and somatosensory evoked potentials
(SSEPs), obtained by stimulating the hand or leg. These tests are used
to evaluate CNS function.
Glasgow coma
scale
A system for assessing level of consciousness by assigning a score to
each of three responses: eye opening, motor responses, and verbal
responses
positron emission Use of radioactive glucose or other metabolically active substance to
tomography
produce images of biochemical activity in tissues. Used for study of the
(PET)
living brain, both healthy and diseased, and also in cardiology.
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Supplementary Terms
Diagnosis and Treatment (cont’d)
Romberg sign
Inability to maintain balance when the eyes are shut and the feet
are close together
sympathectomy
Interruption of sympathetic nerve transmission either surgically or
chemically
trephination
Cutting a piece of bone out of the skull; the instrument used is a
trepan (tre-PAN) or trephine (tre-FIN)
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Supplementary Terms
Psychoactive Drugs
antianxiety agent
Relieve anxiety by means of a calming, sedative effect on the
CNS; for example, chlordiazepoxide (Librium), diazepam (Valium),
alprazolam (Xanax); anxiolytic
antidepressants (other
than those listed in
separate categories
below)
Block the reuptake of neurotransmitters such as serotonin,
norepinephrine, dopamine, alone or in combination; for example,
bupropion (Wellbutrin, Zyban), mirtazapine (Remeron),
nefazodone (Serzone), venlafaxine (Effexor XR), atomoxetine
(Strattera)
monoamine oxidase
inhibitors (MAOI)
Block an enzyme that breaks down norepinephrine and serotonin,
thus prolonging their action; for example, phenelzine (Nardil),
tranylcypromine (Parnate), isocarboxazid (Marplan)
neuroleptics
Drugs used to treat psychosis, including schizophrenia; for
example, clozapine (Clozaril), haloperidol (Haldol), risperidone
(Risperdal), olanzapine (Zyprexa); antipsychotic. Action
mechanism unknown, but may interfere with neurotransmitters
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Supplementary Terms
Psychoactive Drugs
selective serotonin
reuptake inhibitors
(SSRIs)
Block the reuptake of serotonin in the brain, thus increasing levels;
for example, fluoxetine (Prozac), citalopram (Celexa), paroxetine
(Paxil), sertraline (Zoloft)
stimulants
Promote activity and a sense of well-being; for example,
methylphenidate (Ritalin), dextroamphetamine (Dexedrine),
amphetamine + dextroamphetamine (Adderall)
tricyclic
antidepressants
(TCA)
Block the reuptake of norepinephrine, serotonin, or both; for
example, amitriptyline (Elavil), clomipramine (Anafril), imipramine
(Tofranil), doxepin (Sinequan), trimipramine (Surmontil)
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Abbreviations
ACh
Acetylcholine
AD
Alzheimer disease
ADHD
Attention-deficit/hyperactivity disorder
ALS
Amyotrophic lateral sclerosis
ANS
Autonomic nervous system
BAEP
Brainstem auditory evoked potentials
CBF
Cerebral blood flow
CJD
Creutzfeldt–Jakob disease
CNS
Central nervous system
CP
Cerebral palsy
CSF
Cerebrospinal fluid
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Abbreviations (cont’d)
CVA
Cerebrovascular accident
CVD
Cerebrovascular disease
DSM
Diagnostic and Statistical Manual of Mental Disorders
DTR
Deep tendon reflexes
EEG
Electroencephalogram; electroencephalograph(y)
GAD
Generalized anxiety disorder
ICP
Intracranial pressure
LMN
Lower motor neuron
LOC
Level of consciousness
LP
Lumbar puncture
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Abbreviations (cont’d)
MAOI
Monoamine oxidase inhibitor
MID
Multi-infarct dementia
MS
Multiple sclerosis
NICU
Neurological intensive care unit
NPH
Normal pressure hydrocephalus
NREM
Non–rapid eye movement (sleep)
OCD
Obsessive–compulsive disorder
PDD
Pervasive developmental disorder
PET
Positron emission tomography
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Abbreviations (cont’d)
PNS
Peripheral nervous system
PTSD
Posttraumatic stress disorder
RAS
Reticular activating system
REM
Rapid eye movement (sleep)
SSEP
Somatosensory evoked potentials
SSRI
Selective serotonin reuptake inhibitor
TCA
Tricyclic antidepressant
TIA
Transient ischemic attack
UMN
Upper motor neuron
VEP
Visual evoked potentials
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Nervous System
• Controls body functions with electric impulses
• Two physical systems
– Central nervous system
• Brain
• Spinal cord
– Peripheral nervous system
• All other nerve tissue
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Nervous System (cont’d)
• Two functional systems
– Somatic nervous system
• Controls skeletal muscles
– Autonomic nervous system
• Controls:
• Smooth muscles
• Cardiac muscles
• Glands
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Anatomic Divisions of the Nervous System
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The Neuron
• Basic functional unit of nervous system
• Two types of fibers extend from cell body
– Dendrite
• Carries impulses toward cell body
– Axon
• Carries impulses away from cell body
• Some covered with myelin
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The Neuron (cont’d)
• Types of neurons
– Sensory neurons
• Transmit impulses towards CNS
– Motor neurons
• Transmit impulses away from CNS
– Connecting neurons
• Contact at synapse
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Motor Neuron
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Nerves
• Bundles of neuron fibers in PNS
• Ganglion = collection of cell bodies along nerve pathway
• Most nerves contain both sensory and motor fibers
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Roots for the Nervous System and the
Spinal Cord
Root
Meaning
Example
Definition of Example
neur/o, neur/i
nervous system, neurotrophin
nervous tissue,
nerve
factor that promotes nerve
growth (troph/o = nourish)
gli/o
neuroglia
glial
pertaining to neuroglia
gangli/o,
ganglion/o
ganglion
ganglioma
tumor of a ganglion
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Roots for the Nervous System and the
Spinal Cord (cont’d)
Root
Meaning
Example
Definition of Example
mening/o,
meninge/o
meninges
meningocele
hernia of the meninges
myel/o
spinal cord (also
bone marrow)
hematomyelia
hemorrhage into the spinal
cord
radicul/o
spinal nerve root
radiculopathy
any disease of a spinal
nerve root
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Roots for the Brain
Root
Meaning
Example
Definition of Example
encephal/o
brain
anencephaly
absence of a brain
cerebr/o
cerebrum
(loosely, brain)
infracerebral
below the cerebrum
cortic/o
cerebral cortex,
outer portion
corticospinal
pertaining to the cerebral
cortex and spinal cord
cerebell/o
cerebellum
supracerebellar
above the cerebellum
thalam/o
thalamus
thalamotomy
incision of the thalamus
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Roots for the Brain (cont’d)
Root
Meaning
Example
Definition of Example
ventricul/o
cavity, ventricle
intraventricular
within a ventricle
medull/o
medulla
oblongata (also
spinal cord)
medullary
pertaining to the medulla
psych/o
mind
psychogenic
originating in the mind
narc/o
stupor,
unconsciousness
narcosis
state of stupor induced by
drugs
somn/o, somn/i
sleep
somnolence
sleepiness
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Suffixes for the Nervous System
Suffix
Meaning
Example
Definition of Example
-phasia
speech
heterophasia
uttering words that are
different from those
intended
-lalia
speech, babble
coprolalia
compulsive use of obscene
words (copro- means
“feces”)
-lexia
reading
bradylexia
slowness in reading
-plegia
paralysis
tetraplegia
paralysis of all four limbs
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Suffixes for the Nervous System (cont’d)
Suffix
Meaning
Example
Definition of Example
-paresi*
partial paralysis
hemiparesis
partial paralysis of one side of
the body
-lepsy
seizure
narcolepsy
condition marked by sudden
episodes of sleep
-phobia*
persistent,
irrational fear
agoraphobia
fear of being in a public place
(from Greek agora, meaning
“marketplace”)
-mania*
excited state,
obsession
megalomania
exaggerated self-importance;
“delusions of grandeur”
*May be used alone as a word.
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The Brain
• Cerebrum
– Largest part of brain
– Composed mostly of white matter
– Also houses cerebral cortex
• Thin outer layer of gray matter
• Higher brain functions
– Divided into two hemispheres
– Deep groove separates hemispheres
• Called longitudinal fissure
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The Diencephalon
• Contains:
– Thalamus
• Receives sensory information
• Directs info to proper portion of cortex
– Hypothalamus
• Controls pituitary gland
• Serves as link between endocrine and nervous systems
– Pituitary gland
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The Brainstem
• Midbrain
– Contains reflex centers for improved vision and
hearing
• Pons
– Contains fibers that connect different regions of brain
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The Brainstem (cont’d)
• Medulla oblongata
– Connects brain with spinal cord
– All impulses to and from brain pass through
– Controls:
• Heart rate
• Respiration
• Blood pressure
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Cerebellum
• Located:
– Under cerebrum
– Dorsal to pons and medulla
• Controls and maintains:
– Voluntary muscle movements
– Posture
– Coordination
– Balance
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Protecting the Brain
• Four ventricles produce cerebrospinal fluid
• Meninges = set of three protective layers covering brain and
spinal cord
– Dura mater
• Outermost layer
– Arachnoid
• Middle layer
– Pia mater
• Thin, vascular inner layer
• Attached directly to brain and spinal cord tissue
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External Surface of the Brain
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The Spinal Cord
• Extends from medulla oblongata to between 1st and 2nd
lumbar vertebrae
• Consists of:
– Gray matter
• Central area surrounded by white matter
– White matter
• Contains tracts for impulses
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Cross section of the Spinal Cord
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Spinal Nerves
• 31 pairs of spinal nerves connect with spinal cord
• Grouped in segments:
– Cervical (8)
– Thoracic (12)
– Lumbar (5)
– Sacral (5)
– Coccygeal (1)
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Spinal Nerves (cont’d)
• Nerves joins cord by two roots:
– Posterior (dorsal)
• Carries sensory impulses into spinal cord
– Anterior (ventral)
• Carries motor impulses from spinal cord to muscle
or gland
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Autonomic Nervous System
• Controls involuntary actions of muscles and glands
• Divided into two divisions:
– Sympathetic nervous system
– Parasympathetic nervous system
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Autonomic Nervous System (cont’d)
– Sympathetic nervous system
• Stimulates body responses:
• “Fight-or-flight” response
• Increased heart rate
• Increased respiration rate
• Activates adrenal gland
• Delivers more blood to skeletal muscles
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Autonomic Nervous System (cont’d)
– Parasympathetic nervous system
• Returns body to steady state
• Stimulates maintenance activities
– Most organs affected by both divisions
– Sympathetic and parasympathetic have opposite
effects on the body
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Vascular Disorders
• Stroke or cerebrovascular accident
–
Any occurrence of brain tissue not getting oxygen
–
3rd leading cause of death in developed world
–
Leading cause of neurologic disability
–
Risk factors:
• Hypertension
• Atherosclerosis
• Heart disease
• Diabetes mellitus
• Cigarette smoking
• Heredity
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Thrombosis
• Formation of blood clot in vessel, often in carotid artery
• Sudden blockage caused by travelling obstruction termed
embolism
• Diagnosed with:
–
Cerebral angiography
–
CT scans
–
Other radiographic techniques
• Treatment
–
Carotid endarterectomy
–
Drugs to dissolve clot
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Aneurysm
• Localized dilation of vessel
• May rupture and cause hemorrhage
• Causes:
–
Congenital
–
Atherosclerosis
–
Hypertension
• May lead to:
–
Aphasia
–
Hemiplegia
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Trauma
• Cerebral contusion
– Bruise to surface of brain
• Epidural hematoma
– Bleeding between dura mater and skull bone
– Usually results from blow to side of head
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Trauma (cont’d)
• Subdural hematoma
– Bleeding between dura mater and arachnoid
– Usually results from blow to front or back of head
• Concussion
– Can result from blow to head or fall
– May also encounter contrecoup injury
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Locations of Hematomas
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Confusion
• Confusion = state of reduced comprehension, coherence,
reasoning ability
• May include:
– Memory loss
– Loss of language ability
– Reduced alertness
– Emotional changes
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Coma
• Coma = state of unconsciousness from which one can
not be aroused
• Causes:
– Brain injury
– Epilepsy
– Toxins
– Metabolic imbalance
– Respiratory, hepatic, renal failure
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Infections
• Bacterial meningitis
– Inflammation of meninges
• Common symptom is stiff neck
• Diagnosed with lumbar puncture
• Viral meningitis
– Encephalitis (inflammation of the brain)
– Also includes other viruses that affect CNS:
• Rabies
• Polio
• HIV
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Infections (cont’d)
• Shingles
– Nerve infection
– Chickenpox as child, Herpes-zoster virus reactivated
later in life and spread along peripheral nerves
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Neoplasms
• Tumors originating in nervous system, usually involving
neuroglia
• Called gliomas
• Symptoms are dependent on size and location:
–
Seizures
–
Headaches
–
Vomiting
–
Muscle weakness
–
Interference with one of the senses (hearing, vision)
• Meningioma = tumor of meninges
–
Can be removed quickly
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Degenerative Diseases
• Multiple sclerosis
– Patchy loss of myelin with hardening of tissue in CNS
– Symptoms:
• Vision problems
• Tingling, numbness in arms
• Urinary incontinence
• Tremor
• Stiff gait
– Exact cause is unknown
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Degenerative Diseases (cont’d)
• Parkinson disease
–
Failure of midbrain neurons to secrete dopamine
• Leads to:
–
Tremors
–
Muscle rigidity
–
Flexion at joints
–
Akinesia
–
Emotional problems
• Treated with L-dopa
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Degenerative Diseases (cont’d)
• Alzheimer disease
– Unexplained degeneration of neurons
– Atrophy of cerebral cortex
– May cause:
• Progressive loss of recent memory
• Confusion
• Mood changes
• Multi-infarct dementia
–
Symptoms resemble those associated with AD
–
Caused by multiple small strokes
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Epilepsy
• Seizures caused by abnormal electric brain activity
• Seizures vary:
– Brief and mild (petit mal)
– Major (grand mal)
• Serious seizures result in loss of consciousness and
convulsions
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Epilepsy (cont’d)
• Diagnosed with EEG revealing brain activity abnormalities
• Treated with antiepileptic and anticonvulsive drugs
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Sleep Disturbances
• Dyssomnia = general term for sleep disorders
• Insomnia
–
Insufficient or nonrestorative sleep
• Narcolepsy
– Brief, uncontrollable “attacks” of sleep
– Treated with:
• Stimulants
• Regulation of sleep habits
• Short daytime naps
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Sleep Disturbances (cont’d)
• Sleep apnea
–
Failure to breathe for brief periods during sleep
–
Usually results from upper airway obstruction
• Diagnosed with:
–
Physical examination
–
Sleep history
–
Log of sleep habits
• Details of sleep environment
• Consumed substances that may interfere with sleep
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Sleep Disturbances (cont’d)
• Polysomnography
– Study in sleep laboratory
– Characterize two components of sleep
– Non-rapid eye movement (deep sleep stage)
– Rapid eye movement (dream stage)
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Behavioral Disorders
• Anxiety disorders
– Generalized anxiety disorder
• Chronic excessive and uncontrollable worry
• May be accompanied with:
• Muscle tensing
• Restlessness
• Dyspnea
• Palpitations
• Insomnia
• Irritability
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Behavioral Disorders (cont’d)
• Panic disorder
– Anxiety with episodes of intense fear
• Phobias
– Extreme, persistent fears centered around objects or
situations
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Behavioral Disorders (cont’d)
• Obsessive-compulsive disorder (OCD)
– Condition with repetitive behaviors to relieve anxiety
• Posttraumatic stress disorder (PTSD)
– Caused by highly stressful, catastrophic event
– Often associated with other emotional problems
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Depression
• Usually coexists with physical or emotional conditions
• Characterized by feelings of:
– Feelings of sadness
– Hopelessness
– Lack of interest
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Depression (cont’d)
• Dysthymia
– Form of depression triggered by serious event
• Bipolar disorder
– Depression with episodes of mania
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Psychosis
• Mental state with gross misconception of reality
• Characterized by:
– Delusions
– Paranoia
– Hallucinations
• Schizophrenia
– Form of chronic psychosis
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Attention-Deficit/Hyperactivity Disorder
• Difficult to diagnosis
• Usually begins in childhood
• Treatment:
– Psychotherapy or behavioral therapy
– Drugs
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Pervasive Developmental Disorder
• Impairments that appear early in life
• Affect social interactions and communication skills
• Asperger syndrome
– Trouble with social interactions and understanding
other’s behavior
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Pervasive Developmental Disorder
(cont’d)
• Autism
– Complex disorder of unknown cause
– Usually appears between ages 2 and 6
– Marked by:
• Self-absorption
• Lack of response to social contact
• Low intelligence
• Poor language skills
• Inappropriate response to stimuli
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Drugs Used in Treatment
• Psychotropic drugs
– Acts on mental state
• Category of drugs includes:
– Antianxiety (anxiolytics)
– Mood stabilizers
– Antidepressants
– Antipsychotics (neuroleptics)
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Pretest
1. The basic cell of the nervous system is a(n):
(a) myofiber
(b) neuron
(c) osteoblast
(d) chondrocyte
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Pretest
1. The basic cell of the nervous system is a(n):
(a) myofiber
(b) neuron
(c) osteoblast
(d) chondrocyte
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Pretest
2. The largest part of the brain is the:
(a) cortex
(b) adrenal
(c) cerebrum
(d) pituitary
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Pretest
2. The largest part of the brain is the:
(a) cortex
(b) adrenal
(c) cerebrum
(d) pituitary
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Pretest
3. The midbrain, pons, and medulla oblongata make up
the:
(a) brainstem
(b) spinal cord
(c) cerebellum
(d) thymus
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Pretest
3. The midbrain, pons, and medulla oblongata make up
the:
(a) brainstem
(b) spinal cord
(c) cerebellum
(d) thymus
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Pretest
4. Involuntary responses are controlled by the:
(a) voluntary nervous system
(b) somatic nervous system
(c) autonomic nervous system
(d) diaphragm
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Pretest
4. Involuntary responses are controlled by the:
(a) voluntary nervous system
(b) somatic nervous system
(c) autonomic nervous system
(d) diaphragm
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Pretest
5. A simple response that requires few cells is a:
(a) reflex
(b) mutation
(c) sensation
(d) stimulus
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Pretest
5. A simple response that requires few cells is a:
(a) reflex
(b) mutation
(c) sensation
(d) stimulus
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Pretest
6. A disorder, often of unknown cause, characterized by
seizures is called:
(a) cystic fibrosis
(b) spina bifida
(c) epilepsy
(d) thyrotoxicosis
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Pretest
6. A disorder, often of unknown cause, characterized by
seizures is called:
(a) cystic fibrosis
(b) spina bifida
(c) epilepsy
(d) thyrotoxicosis
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Pretest
7. An instrument used to study the electrical activity of the
brain is the:
(a) electrocardiograph
(b) electroencephalograph
(c) CT scanner
(d) sonograph
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Pretest
7. An instrument used to study the electrical activity of the
brain is the:
(a) electrocardiograph
(b) electroencephalograph
(c) CT scanner
(d) sonograph
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Pretest
8. An extreme, persistent fear is a(n):
(a) palliative
(b) prognosis
(c) phobia
(d) analgesic
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Pretest
8. An extreme, persistent fear is a(n):
(a) palliative
(b) prognosis
(c) phobia
(d) analgesic
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