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Transcript of The Nervous System and Behavioral Disorders. Nervous System Controls body functions with electric...
The Nervous System and Behavioral Disorders
Nervous System Controls body functions with electric
impulses Two physical systems
Central nervous system Brain Spinal cord
Peripheral nervous system All other nerve tissue
Nervous System (con’t) Two functional systems
Somatic nervous system Controls skeletal muscles
Autonomic nervous system Controls:
Smooth muscles Cardiac muscles Glands
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
The Neuron (con’t)
Types of neurons Sensory neurons
Transmit impulses towards CNS Motor neurons
Transmit impulses away from CNS Connecting neurons
Contact at synapse
Nerves
Bundles of neuron fibers in PNS Ganglion = collection of cell bodies
along nerve pathway Most nerves contain both sensory
and motor fibers
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
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
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
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
Trauma Epidural hematoma
Bleeding between dura mater and skull bone Usually results from blow to side of head
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
Infections Bacterial meningitis
Inflammation of meninges Common symptom is stiff neck Diagnosed with lumbar puncture
Viral meningitis (another form) Encephalitis (inflammation of the brain) Also includes other viruses that affect CNS:
Rabies Polio HIV
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)
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
Degenerative Diseases (con’t)
Parkinson disease Failure of midbrain neurons to secrete
dopamine Leads to:
Tremors Muscle rigidity Flexion at joints Akinesia Emotional problems
Treated with L-dopa
Degenerative Diseases (con’t)
Alzheimer disease Unexplained degeneration of
neurons Atrophy of cerebral cortex May cause:
Progressive loss of recent memory Confusion Mood changes
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
Diagnosed with EEG revealing brain activity abnormalities
Treated with antiepileptic and anticonvulsive drugs
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
Sleep apnea Failure to breathe for brief periods during sleep Usually results from upper airway obstruction
Behavioral Disorders Anxiety disorders
Generalized anxiety disorder Chronic excessive and uncontrollable
worry May be accompanied with:
Muscle tensing Restlessness Dyspnea Palpitations Insomnia Irritability
Behavioral Disorders (con’t) Panic disorder
Anxiety with episodes of intense fear Phobias
Extreme, persistent fears centered around objects or situations
Obsessive-compulsive disorder Condition w/ repetitive behaviors to relieve
anxiety Attention-deficit-hyperactivity disorder
Difficult to diagnose due to overlapping symptoms
Treated with stimulant drugs
Depression Usually coexists with physical or
emotional conditions Characterized by feelings of:
Feelings of sadness Hopelessness Lack of interest
Dysthymia Form of depression triggered by
serious event Bipolar disorder
Depression with episodes of mania
Psychosis Mental state with gross
misconception of reality Characterized by:
Delusions Paranoia Hallucinations
Schizophrenia From of chronic psychosis
Drugs Used in Treatment Psychotropic drugs
Acts on mental state Category of drugs includes:
Antianxiety (anxiolytics) Mood stabilizers Antidepressants Antipsychotics (neuroleptics)