Transcript Nervous system

The Nervous System and
Behavioral Disorders
Nervous System
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Controls body functions with electric
impulses
Two physical systems
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Central nervous system
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Brain
Spinal cord
Peripheral nervous system
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All other nerve tissue
Nervous System (con’t)
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Two functional systems
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Somatic nervous system
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Controls skeletal muscles
Autonomic nervous system
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Controls:
 Smooth muscles
 Cardiac muscles
 Glands
The Neuron
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Basic functional unit of nervous system
Two types of fibers extend from cell body
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Dendrite
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Carries impulses toward cell body
Axon
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Carries impulses away from cell body
Some covered with myelin
The Neuron (con’t)
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Types of neurons
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Sensory neurons
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Motor neurons
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Transmit impulses towards CNS
Transmit impulses away from CNS
Connecting neurons
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Contact at synapse
Nerves
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Bundles of neuron fibers in PNS
Ganglion = collection of cell bodies along
nerve pathway
Most nerves contain both sensory and
motor fibers
The Brain
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Cerebrum
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Largest part of brain
Composed mostly of white matter
Also houses cerebral cortex
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Thin outer layer of gray matter
Higher brain functions
Divided into two hemispheres
Deep groove separates hemispheres
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Called longitudinal fissure
Meninges
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Set of three protective layers covering brain
and spinal cord
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Dura mater
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Arachnoid
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Outermost layer
Middle layer
Pia mater
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Thin, vascular inner layer
Attached directly to brain and spinal cord tissue
The Spinal Cord
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Extends from medulla oblongata to
between 1st and 2nd lumbar vertebrae
Consists of:
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Gray matter
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Central area surrounded by white matter
White matter
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Contains tracts for impulses
Vascular Disorders
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Stroke or cerebrovascular accident
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Any occurrence of brain tissue not getting oxygen
3rd leading cause of death in developed world
Leading cause of neurologic disability
Risk factors:
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Hypertension
Atherosclerosis
Heart disease
Diabetes mellitus
Cigarette smoking
Heredity
Trauma
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Epidural hematoma
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Subdural hematoma
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Bleeding between dura mater and skull bone
Usually results from blow to side of head
Bleeding between dura mater and arachnoid
Usually results from blow to front or back of head
Concussion
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Can result from blow to head or fall
May also encounter contrecoup injury
Infections
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Bacterial meningitis
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Inflammation of meninges
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Common symptom is stiff neck
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Diagnosed with lumbar puncture
Viral meningitis (another form)
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Encephalitis (inflammation of the brain)
Also includes other viruses that affect CNS:
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Rabies
Polio
HIV
Neoplasms
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Tumors originating in nervous system, usually
involving neuroglia
Called gliomas
Symptoms are dependent on size and location:
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Seizures
Headaches
Vomiting
Muscle weakness
Interference with one of the senses (hearing,
vision)
Degenerative Diseases
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Multiple sclerosis
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Patchy loss of myelin with hardening of tissue in
CNS
Symptoms:
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Vision problems
Tingling, numbness in arms
Urinary incontinence
Tremor
Stiff gait
Exact cause is unknown
Degenerative Diseases (con’t)
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Parkinson disease
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Leads to:
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Failure of midbrain neurons to secrete dopamine
Tremors
Muscle rigidity
Flexion at joints
Akinesia
Emotional problems
Treated with L-dopa
Degenerative Diseases (con’t)
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Alzheimer disease
 Unexplained degeneration of
neurons
 Atrophy of cerebral cortex
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May cause:
 Progressive loss of recent memory
 Confusion
 Mood changes
Epilepsy
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Seizures caused by abnormal electric brain activity
Seizures vary:
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Brief and mild (petit mal)
Major (grand mal)
Serious seizures result in loss of consciousness and
convulsions
Diagnosed with EEG revealing brain activity
abnormalities
Treated with antiepileptic and anticonvulsive drugs
Sleep Disturbances
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Dyssomnia = general term for sleep disorders
Insomnia
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Insufficient or nonrestorative sleep
Narcolepsy
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Brief, uncontrollable “attacks” of sleep
Treated with:
Stimulants
 Regulation of sleep habits
 Short daytime naps
Sleep apnea
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Failure to breathe for brief periods during sleep
Usually results from upper airway obstruction
Behavioral Disorders
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Anxiety disorders
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Generalized anxiety disorder
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Chronic excessive and uncontrollable worry
May be accompanied with:
 Muscle tensing
 Restlessness
 Dyspnea
 Palpitations
 Insomnia
 Irritability
Behavioral Disorders (con’t)
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Panic disorder
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Phobias
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Extreme, persistent fears centered around objects
or situations
Obsessive-compulsive disorder
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Anxiety with episodes of intense fear
Condition w/ repetitive behaviors to relieve
anxiety
Attention-deficit-hyperactivity disorder
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Difficult to diagnose due to overlapping
symptoms
Treated with stimulant drugs
Depression
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Usually coexists with physical or
emotional conditions
Characterized by feelings of:
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Dysthymia
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Feelings of sadness
Hopelessness
Lack of interest
Form of depression triggered by serious
event
Bipolar disorder
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Depression with episodes of mania
Psychosis
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Mental state with gross misconception of
reality
Characterized by:
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Delusions
Paranoia
Hallucinations
Schizophrenia
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From of chronic psychosis
Drugs Used in Treatment
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Psychotropic drugs
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Acts on mental state
Category of drugs includes:
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Antianxiety (anxiolytics)
Mood stabilizers
Antidepressants
Antipsychotics (neuroleptics)