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Chapter 17: The Nervous System and Behavioral Disorders

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.

afferent arachnoid mater autonomic nervous system (ANS) axon brain brainstem central nervous system (CNS)

Key Terms Normal Structure and Function

Carrying toward a given point, such as the sensory neurons and nerves that carry impulses toward the CNS (root fer means “to carry”) The middle layer of the meninges (from the Greek word for spider, because this tissue resembles a spider web) The division of the nervous system that regulates involuntary activities, controlling smooth muscles, cardiac muscle, and glands; the visceral nervous system The fiber of a neuron that conducts impulses away from the cell body The nervous tissue contained within the cranium; consists of the cerebrum, diencephalon, brainstem, and cerebellum (root:

encephal/o

Key Terms Normal Structure and Function (cont’d)

cerebellum cerebral cortex cerebrum cerebrospinal fluid (CSF) cranial nerves dendrite diencephalons dura mater

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

) The cerebrum's thin surface layer of gray matter (the cortex is the outer region of an organ) (root:

cortic/o

) The large upper portion of the brain; it is divided into two hemispheres by the longitudinal fissure (root:

cerebr/o

) The watery fluid that circulates in and around the brain and spinal cord as a protection The 12 pairs of nerves that are connected to the brain A fiber of a neuron that conducts impulses toward the cell body The part of the brain that contains the thalamus, hypothalamus, and pituitary gland; located between the cerebrum and the brainstem The strong, fibrous outermost layer of the meninges Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Normal Structure and Function (cont’d)

efferent ganglion gray matter gyrus hypothalamus interneuron medulla oblongata

Carrying away from a given point, such as the motor neurons and nerves that carry impulses away from the CNS (root carry”)

fer

means “to A collection of nerve cell bodies outside the CNS (plural: ganglia) (root:

gangli/o, ganglion/o

) Unmyelinated tissue of the nervous system A raised convolution of the surface of the cerebrum (plural: gyri) The part of the brain that controls the pituitary gland and maintains homeostasis Any neuron located between a sensory and a motor neuron in a neural pathway, such as the neurons that transmit impulses within the CNS 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

Key Terms Normal Structure and Function (cont’d)

meninges midbrain motor myelin neuroglia neuron neurotransmitter

The three membranes that cover the brain and spinal cord (singular: meninx) (root:

mening/o, meninge/o

) The part of the brainstem between the diencephalon and the pons; contains centers for coordination of reflexes for vision and hearing Producing movement; describes neurons that carry impulses away from the CNS A whitish, fatty substance that surrounds certain axons of the nervous system The supportive cells of the nervous system; also called glial cells (from

glia

meaning “glue”; root:

gli/o

) The basic unit of the nervous system; a nerve cell 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) Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Normal Structure and Function (cont’d)

nerve parasympathetic nervous system

A bundle of nerve cell fibers outside the CNS (root:

neur/o

) 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.

The portion of the nervous system outside the CNS

peripheral nervous system (PNS) pia mater pons reflex root

The innermost layer of the meninges A rounded area on the ventral surface of the brainstem; contains fibers that connect regions of the brain; adjective: pontine (

PON-ten

) A simple, rapid, and automatic response to a stimulus 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

Key Terms Normal Structure and Function (cont’d)

sensory somatic nervous system spinal cord spinal nerves sulcus sympathetic nervous system synapse

Describing neurons that carry impulses toward the CNS The division of the nervous system that controls skeletal (voluntary) muscles The nervous tissue contained within the spinal column; extends from the medulla oblongata to the second lumbar vertebra (root:

myel/o

) The 31 pairs of nerves that connect with the spinal cord A shallow furrow or groove, as on the surface of the cerebrum (plural: sulci) 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 The junction between two neurons; also the junction between a motor neuron and a muscle or gland Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Normal Structure and Function (cont’d)

thalamus tract ventricle visceral nervous system white matter

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

) A bundle of nerve cell fibers within the CNS A small cavity, such as one of the cavities in the brain in which CSF is produced (root:

ventricul/o

Key Terms Neurologic Disorders

Alzheimer disease (AD) amyloid aneurysm aphasia astrocytoma cerebral contusion

A form of dementia caused by atrophy of the cerebral cortex; presenile dementia A starchlike substance of unknown composition that accumulates in the brain in Alzheimer and other diseases A localized abnormal dilation of a blood vessel that results from weakness of the vessel wall; an aneurysm may eventually burst 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 A neuroglial tumor composed of astrocytes A bruise to the surface of the brain following a blow to the head Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

cerebrovascular accident (CVA) coma concussion confusion contrecoup injury convulsion

Key Terms Neurologic Disorders (cont’d)

Sudden damage to the brain resulting from reduction of cerebral blood flow; possible causes are atherosclerosis, thrombosis, or a ruptured aneurysm; commonly called stroke State of deep unconsciousness from which one cannot be roused Injury resulting from a violent blow or shock; a concussion of the brain usually results in loss of consciousness A state of reduced comprehension, coherence, and reasoning ability resulting in inappropriate responses to environmental stimuli 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”) 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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Neurologic Disorders (cont’d)

dementia embolism encephalitis epidural hematoma epilepsy glioma hemiparesis hemiplegia

A gradual and usually irreversible loss of intellectual function Obstruction of a blood vessel by a blood clot or other material carried in the circulation Inflammation of the brain Accumulation of blood in the epidural space (between the dura mater and the skull) A chronic disease involving periodic sudden bursts of electric activity from the brain, resulting in seizures A tumor of neuroglia cells Partial paralysis or weakness of one side of the body Paralysis of one side of the body Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Neurologic Disorders (cont’d)

hydrocephalus insomnia meningioma meningitis multi-infarct dementia (MID) multiple sclerosis (MS) narcolepsy

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 Insufficient or nonrestorative sleep despite ample opportunity to sleep Tumor of the meninges Inflammation of the meninges 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 A chronic, progressive disease involving loss of myelin in the CNS Brief, uncontrollable episodes of sleep during the day Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

neurilemoma paralysis parkinsonism seizure shingles

Key Terms Neurologic Disorders (cont’d)

A tumor of the sheath (neurilemma) of a peripheral nerve; schwannoma 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 A disorder originating in the basal ganglia and characterized by slow movements, tremor, rigidity, and masklike face. Also called Parkinson disease 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 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

sleep apnea stroke subdural hematoma thrombosis tremor

Key Terms Neurologic Disorders (cont’d)

Brief periods of breathing cessation during sleep 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) Accumulation of blood beneath the dura mater Development of a blood clot within a vessel A shaking or involuntary movement Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Diagnosis and Treatment

carotid endarterectomy cerebral angiography electroencephalography (EEG) L-dopa lumbar puncture polysomnography

Surgical removal of the lining of the carotid artery, the large artery in the neck that supplies blood to the brain Radiographic study of the blood vessels of the brain after injection of a contrast medium Amplification, recording, and interpretation of the brain’s electric activity A drug used in the treatment of parkinsonism; levodopa 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 Simultaneous monitoring of a variety of physiologic functions during sleep to diagnose sleep disorders Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Behavioral Disorders

anxiety Asperger syndrome attention-deficit / hyperactivity disorder (ADHD) autism bipolar disorder delusion

A feeling of fear, worry, uneasiness, or dread A behavioral condition on a continuum with autism that may include difficulty with social interactions and understanding, strong specific interests, and repetitive behaviors A condition that begins in childhood and is characterized by attention problems, easy boredom, impulsive behavior, and hyperactivity 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”) A form of depression with episodes of mania (a state of elation); manic depressive illness A false belief inconsistent with knowledge and experience Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Behavioral Disorders (cont’d)

depression dysthymia hallucination mania obsessive compulsive disorder (OCD) panic disorder

A mental state characterized by profound feelings of sadness, emptiness, hopelessness, and lack of interest or pleasure in activities A mild form of depression that usually develops in response to a serious life event (from

dys

- and Greek

thymos

, meaning “mind, emotion”) A false perception unrelated to reality or external stimuli A state of elation, which may include agitation, hyperexcitability, or hyperactivity (adjective: manic) A condition associated with recurrent and intrusive thoughts, images, and repetitive behaviors performed to relieve anxiety A form of anxiety disorder marked by episodes of intense fear Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Behavioral Disorders (cont’d)

paranoia phobia posttraumatic stress disorder (PTSD) psychosis schizophrenia

A mental state characterized by jealousy, delusions of persecution, or perceptions of threat or harm An extreme, persistent fear of a specific object or situation Persistent emotional disturbances that follow exposure to life threatening, catastrophic events, such as trauma, abuse, natural disasters, and warfare A mental disorder extreme enough to cause gross misperception of reality with delusions and hallucinations A poorly understood group of severe mental disorders with features of ( psychosis, delusions, hallucinations, and withdrawn or bizarre behavior

schizo

means “split” and

phren

Supplementary Terms Normal Structure and Function

acetylcholine basal ganglia blood –brain barrier Broca area circle of Willis contralateral

A neurotransmitter; activity involving acetylcholine is described as cholinergic Four masses of gray matter in the cerebrum and upper brainstem that are involved in movement and coordination A special membrane between circulating blood and the brain that prevents certain damaging substances from reaching brain tissue An area in the left frontal lobe of the cerebrum that controls speech production An interconnection (anastomosis) of several arteries supplying the brain, located at the base of the cerebrum Affecting the opposite side of the body Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Normal Structure and Function (cont’d)

corpus callosum dermatome epinephrine ipsilateral leptomeninges nucleus

A large band of connecting fibers between the cerebral hemispheres 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) A neurotransmitter; also called adrenaline; activity involving epinephrine is described as adrenergic On the same side; unilateral The pia mater and arachnoid together A collection of nerve cells within the central nervous system Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Normal Structure and Function (cont’d)

plexus Wernicke area

A network, as of nerves or blood vessels

pyramidal tracts reticular activating system (RAS) Schwann cells

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.

A widespread system in the brain that maintains wakefulness Cells that produce the myelin sheath around peripheral axons An area in the temporal lobe concerned with speech comprehension Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

amyotrophic lateral sclerosis (ALS) amnesia

Supplementary Terms Symptoms and Conditions

A disorder marked by muscular weakness, spasticity, and exaggerated reflexes caused by degeneration of motor neurons; Lou Gehrig disease Loss of memory

apraxia ataxia athetosis Bell palsy berry aneurysm catatonia cerebral palsy

Inability to move with purpose or to use objects properly Lack of muscle coordination; dyssynergia Involuntary, slow, twisting movements in the arms, especially the hands and fingers Paralysis of the facial nerve A small saclike aneurysm of a cerebral artery A phase of schizophrenia in which the patient is unresponsive; there is a tendency to remain in a fixed position without moving or talking A nonprogressive neuromuscular disorder usually caused by damage to the CNS near the time of birth. May include spasticity, involuntary movements, or ataxia Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

chorea

Supplementary Terms Symptoms and Conditions (cont’d)

claustrophobia compulsion Creutzfeldt –Jakob disease (CJD) delirium dysarthria dysmetria

A nervous condition marked by involuntary twitching of the limbs or facial muscles Fear of being shut in or enclosed (from Latin

claudere

, “to shut”) A repetitive, stereotyped act performed to relieve tension A slow-growing degenerative brain disease caused by a prion (

PRĪ on

), an infectious protein. Related to bovine spongiform encephalopathy (BSE, “mad cow disease”) in cattle A sudden and temporary state of confusion marked by excitement, physical restlessness, and incoherence Defect in speech articulation caused by lack of control over the required muscles 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.

Supplementary Terms Symptoms and Conditions (cont’d)

euphoria glioblastoma Guillain –Barré syndrome hematomyelia hemiballism Huntington disease hypochondriasis ictus

An exaggerated feeling of well-being; elation A malignant astrocytoma 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 Hemorrhage of blood into the spinal cord, as from an injury Jerking, twitching movements of one side of the body 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.

Supplementary Terms Symptoms and Conditions (cont’d)

lethargy migraine neurofibromatosis neurosis paraplegia parasomnia quadriplegia

A state of sluggishness or stupor 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 A condition involving multiple tumors of peripheral nerves An emotional disorder caused by unresolved conflicts, with anxiety as a main characteristic Paralysis of the legs and lower part of the body Condition of having undesirable phenomena, such as nightmares, occur during sleep or become worse during sleep Paralysis of all four limbs; tetraplegia Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Symptoms and Conditions (cont’d)

Reye syndrome sciatica somatoform disorders somnambulism stupor syringomyelia tic

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 Neuritis characterized by severe pain along the sciatic nerve and its branches Conditions associated with symptoms of physical disease, such as pain, hypertension, or chronic fatigue, with no physical basis Walking or performing other motor functions while asleep and out of bed; sleepwalking A state of unconsciousness or lethargy with loss of responsiveness A progressive disease marked by formation of fluid-filled cavities in the spinal cord Involuntary, spasmodic, recurrent, and purposeless motor movements or vocalizations Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Symptoms and Conditions (cont’d)

tic douloureux tabes dorsalis Tourette syndrome transient ischemic attack Wallerian degeneration whiplash

Episodes of extreme pain in the area supplied by the trigeminal nerve; also called trigeminal neuralgia 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 A tic disorder with intermittent motor and vocal manifestations that begins in childhood. There also may be obsessive and compulsive behavior, hyperactivity, and distractibility A sudden, brief, and temporary cerebral dysfunction usually caused by interruption of blood flow to the brain Degeneration of a nerve distal to an injury Cervical injury caused by rapid acceleration and deceleration resulting in damage to muscles, ligaments, disks, and nerves Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Diagnosis and Treatment

Babinski reflex evoked potentials Glasgow coma scale

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.

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.

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 tomography (PET)

Use of radioactive glucose or other metabolically active substance to produce images of biochemical activity in tissues. Used for study of the living brain, both healthy and diseased, and also in cardiology. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Diagnosis and Treatment (cont’d)

Romberg sign sympathectomy trephination

Inability to maintain balance when the eyes are shut and the feet are close together Interruption of sympathetic nerve transmission either surgically or chemically Cutting a piece of bone out of the skull; the instrument used is a trepan (

tre-PAN

) or trephine (

tre-FIN

Supplementary Terms Psychoactive Drugs

antianxiety agent antidepressants

(other than those listed in separate categories below)

monoamine oxidase inhibitors (MAOI) neuroleptics

Relieve anxiety by means of a calming, sedative effect on the CNS; for example, chlordiazepoxide (Librium), diazepam (Valium), alprazolam (Xanax); anxiolytic 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) Block an enzyme that breaks down norepinephrine and serotonin, thus prolonging their action; for example, phenelzine (Nardil), tranylcypromine (Parnate), isocarboxazid (Marplan) 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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Psychoactive Drugs

selective serotonin reuptake inhibitors (SSRIs) stimulants tricyclic antidepressants (TCA)

Block the reuptake of serotonin in the brain, thus increasing levels; for example, fluoxetine (Prozac), citalopram (Celexa), paroxetine (Paxil), sertraline (Zoloft) Promote activity and a sense of well-being; for example, methylphenidate (Ritalin), dextroamphetamine (Dexedrine), amphetamine + dextroamphetamine (Adderall) Block the reuptake of norepinephrine, serotonin, or both; for example, amitriptyline (Elavil), clomipramine (Anafril), imipramine (Tofranil), doxepin (Sinequan), trimipramine (Surmontil) Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

ACh AD ADHD ALS ANS BAEP CBF CJD CNS CP CSF

Abbreviations

Acetylcholine Alzheimer disease Attention-deficit/hyperactivity disorder Amyotrophic lateral sclerosis Autonomic nervous system Brainstem auditory evoked potentials Cerebral blood flow Creutzfeldt –Jakob disease Central nervous system Cerebral palsy Cerebrospinal fluid Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

CVA CVD DSM DTR EEG GAD ICP LMN LOC LP

Abbreviations (cont’d)

Cerebrovascular accident Cerebrovascular disease Diagnostic and Statistical Manual of Mental Disorders Deep tendon reflexes Electroencephalogram; electroencephalograph(y) Generalized anxiety disorder Intracranial pressure Lower motor neuron Level of consciousness Lumbar puncture Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

MAOI MID MS NICU NPH NREM OCD PDD PET

Abbreviations (cont’d)

Monoamine oxidase inhibitor Multi-infarct dementia Multiple sclerosis Neurological intensive care unit Normal pressure hydrocephalus Non –rapid eye movement (sleep) Obsessive –compulsive disorder Pervasive developmental disorder Positron emission tomography Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

PNS PTSD RAS REM SSEP SSRI TCA TIA UMN VEP

Abbreviations (cont’d)

Peripheral nervous system Posttraumatic stress disorder Reticular activating system Rapid eye movement (sleep) Somatosensory evoked potentials Selective serotonin reuptake inhibitor Tricyclic antidepressant Transient ischemic attack Upper motor neuron Visual evoked potentials Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Nervous System

• Controls body functions with electric impulses • Two physical systems – Central nervous system – • Brain • Spinal cord Peripheral nervous system • All other nerve tissue Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Nervous System (cont’d)

• Two functional systems – Somatic nervous system • Controls skeletal muscles – Autonomic nervous system • Controls: • Smooth muscles • Cardiac muscles • Glands Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Anatomic Divisions of the Nervous System

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Motor Neuron

Nerves

• Bundles of neuron fibers in PNS • Ganglion = collection of cell bodies along nerve pathway • Most nerves contain both sensory and motor fibers Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Roots for the Nervous System and the Spinal Cord

Root

neur/o, neur/i gli/o gangli/o, ganglion/o

Meaning

nervous system, nervous tissue, nerve neuroglia ganglion

Example

neurotrophin glial ganglioma

Definition of Example

factor that promotes nerve growth (

troph/o

Roots for the Nervous System and the Spinal Cord (cont’d)

Root

mening/o, meninge/o myel/o radicul/o

Meaning

meninges

Example

meningocele spinal cord (also bone marrow) spinal nerve root hematomyelia radiculopathy

Definition of Example

Roots for the Brain

Root

encephal/o cerebr/o cortic/o cerebell/o thalam/o

Meaning

brain cerebrum (loosely, brain) cerebral cortex, outer portion cerebellum thalamus

Example

anencephaly infracerebral corticospinal supracerebellar thalamotomy

Definition of Example

absence of a brain below the cerebrum pertaining to the cerebral cortex and spinal cord above the cerebellum incision of the thalamus Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Roots for the Brain (cont’d)

Root

ventricul/o medull/o psych/o narc/o somn/o, somn/i

Meaning

cavity, ventricle medulla oblongata (also spinal cord) mind stupor, unconsciousness sleep

Example

intraventricular medullary psychogenic narcosis somnolence

Definition of Example

Suffixes for the Nervous System

Suffix

-phasia -lalia -lexia -plegia

Meaning

speech reading paralysis

Example

heterophasia speech, babble coprolalia bradylexia tetraplegia

Definition of Example

uttering words that are different from those intended compulsive use of obscene words (

copro

Suffixes for the Nervous System (cont’d)

Suffix

-paresi*

Meaning

partial paralysis

Example

hemiparesis -lepsy -phobia* seizure persistent, irrational fear narcolepsy agoraphobia -mania* excited state, obsession *May be used alone as a word.

megalomania

Definition of Example

partial paralysis of one side of the body condition marked by sudden episodes of sleep fear of being in a public place (from Greek

agora

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

The Brainstem

• Midbrain – Contains reflex centers for improved vision and hearing • Pons – Contains fibers that connect different regions of brain Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Cerebellum

• Located: – Under cerebrum – Dorsal to pons and medulla • Controls and maintains: – Voluntary muscle movements – – – Posture Coordination Balance Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

External Surface of the Brain

The Spinal Cord

• Extends from medulla oblongata to between 1 st lumbar vertebrae and 2 nd • Consists of: – – Gray matter • Central area surrounded by white matter White matter • Contains tracts for impulses Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Cross section of the Spinal Cord

Spinal Nerves

• 31 pairs of spinal nerves connect with spinal cord • Grouped in segments: – – Cervical (8) Thoracic (12) – – – Lumbar (5) Sacral (5) Coccygeal (1) Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Autonomic Nervous System

• Controls involuntary actions of muscles and glands • Divided into two divisions: – – Sympathetic nervous system Parasympathetic nervous system Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Vascular Disorders

• Stroke or cerebrovascular accident – – – – Any occurrence of brain tissue not getting oxygen 3 rd leading cause of death in developed world Leading cause of neurologic disability Risk factors: • Hypertension • Atherosclerosis • Heart disease • Diabetes mellitus • Cigarette smoking • Heredity Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Aneurysm

• Localized dilation of vessel • May rupture and cause hemorrhage • Causes: – – – Congenital Atherosclerosis Hypertension • May lead to: – – Aphasia Hemiplegia Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Locations of Hematomas

Confusion

• Confusion = state of reduced comprehension, coherence, reasoning ability • May include: – – – – Memory loss Loss of language ability Reduced alertness Emotional changes Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Coma

• Coma = state of unconsciousness from which one can not be aroused • Causes: – – – – – Brain injury Epilepsy Toxins Metabolic imbalance Respiratory, hepatic, renal failure Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Infections (cont’d)

• Shingles – – Nerve infection Chickenpox as child, Herpes-zoster virus reactivated later in life and spread along peripheral nerves Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Epilepsy (cont’d)

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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) Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Behavioral Disorders

• Anxiety disorders – Generalized anxiety disorder • Chronic excessive and uncontrollable worry • May be accompanied with: • Muscle tensing • Restlessness • Dyspnea • Palpitations • Insomnia • Irritability Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Behavioral Disorders (cont’d)

• Panic disorder – Anxiety with episodes of intense fear • Phobias – Extreme, persistent fears centered around objects or situations Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Depression

• Usually coexists with physical or emotional conditions • Characterized by feelings of: – – Feelings of sadness Hopelessness – Lack of interest Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Depression (cont’d)

Psychosis

• Mental state with gross misconception of reality • Characterized by: – – Delusions Paranoia – – Hallucinations • Schizophrenia Form of chronic psychosis Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Attention-Deficit/Hyperactivity Disorder

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Drugs Used in Treatment

• Psychotropic drugs – – Acts on mental state • Category of drugs includes: Antianxiety (anxiolytics) – – – Mood stabilizers Antidepressants Antipsychotics (neuroleptics) Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Pretest

The basic cell of the nervous system is a(n) : (a) myofiber

(b) neuron

Pretest

The largest part of the brain is the : (a) cortex (b) adrenal

(c) cerebrum

Pretest

The midbrain, pons, and medulla oblongata make up the :

(a) brainstem

Pretest

Involuntary responses are controlled by the: (a) voluntary nervous system (b) somatic nervous system (c) autonomic nervous system (d) diaphragm Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Pretest

Involuntary responses are controlled by the: (a) voluntary nervous system (b) somatic nervous system

(c) autonomic nervous system

Pretest

A simple response that requires few cells is a:

(a) reflex

Pretest

A disorder, often of unknown cause, characterized by seizures is called: (a) cystic fibrosis (b) spina bifida (c) epilepsy (d) thyrotoxicosis Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Pretest

A disorder, often of unknown cause, characterized by seizures is called: (a) cystic fibrosis (b) spina bifida

(c) epilepsy

Pretest

An instrument used to study the electrical activity of the brain is the: (a) electrocardiograph (b) electroencephalograph (c) CT scanner (d) sonograph Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Pretest

An instrument used to study the electrical activity of the brain is the: (a) electrocardiograph

(b) electroencephalograph

Pretest

An extreme, persistent fear is a(n): (a) palliative (b) prognosis

(c) phobia