Medical Terminology Nervous System Chapter 15
Dec 22, 2015
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Nervous System
Coordinates many activities of the body– senses changes in internal and external
environment– interprets these changes– coordinates appropriate response in order
to maintain homeostasis When the brain ceases functioning, the
body dies
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Structures
nerve is one or more bundles of impulse carrying fibers that connect the brain & spinal cord with body
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Nervous Tissue
Neurons - transmit impulses– sensory (afferent, ascending)– motor (efferent, descending)
Neuroglia - support neurons
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Neuron dendrites-rootlike structures that receive
impulses and conduct them to the cell body
cell body - contains nucleus axon-extends away from the cell body
and conducts impulses away from the nerve cell
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Neuron Anatomy
Myelin sheath - – insulation– accelerates impulse transmission– appears as white covering
myelin on axons in brain and spinal cord gives white appearance
unmyelinated fibers, dendrites, and nerve cell bodies comprise gray matter of brain and spinal cord
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Neuron Anatomy(peripheral nerves)
Schwann cell– type of neuroglial cell wrapped around
axon – forms the myelin sheath
Neurolemma (neurolemmal sheath)– permits a damaged axon to regenerate– neurolemma NOT found in Central nerves
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Neurotransmitters
Synapse- space between two neurons or between a neuron and a receptor organ.
Impulses are passed from one neuron to another at a junction called the synapse.
Electrical current within neuron causes release of chemical substance called a neurotransmitter.
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Neurotransmitter diffuses across the synapse to receptor sites on the dendrite of the next neuron.
Generates the next electrical stimulus. Terminal ends of the axon release a transmitter
substance that affects the dendrites of the next neuron.
One way transmission of the impulse is assured because only the axons release these chemicals.
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Neuroglia
gli/o or nerve glue neuroglia or glial cells astrocytes - blood brain barrier oligodendrocytes - facilitate myelin
development microglia - phagocytic properties ependyma - assist in CSF circulation
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Divisions
Central Nervous System– brain and spinal cord
Peripheral Nervous System– cranial nerves and spinal nerves
– fibers are sensory or motor
Autonomic Nervous System– ganglia on either side of the spinal cord
sympathetic nervous system parasympathetic nervous system
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Cerebrum
Cerebellum
MedullaOblongata
Cerebrum
Two hemispheres divided by a fissureLobes frontal, parietal, temporal, occipitalCortex, gray color
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Lobes Frontal
– motor functions Parietal
– receives & interprets information Occipital
– eyesight Temporal
– hearing & smell
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Cerebellum
receives incoming messages regarding movement within joints, muscle tone, and position of the body.
relay these messages to other parts of brain to control skeletal activity
movement, coordination, balance
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Hypothalamus-a regulator
Autonomic Nervous System emotional responses/behavior body temperature food intake= hunger water balance and thirst sleep-wake cycles endocrine system activity
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Brainstem
stalk-like portion of the brain– midbrain - conduction pathways– pons - nerve cells cross from one side to
the other– medulla oblongata - basic life functions
origin for 10 of 12 cranial nerves– controls respiration, blood pressure, heart
rate
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Spinal Cord housed within vertebral column continuos with brain stem ascending and descending nerve tracts protected by CSF and meninges gray matter in internal section - not
protected by myelin sheath myelinated white matter in outer area
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Meninges dura mater
– epidural– subdural
arachnoid – subarachnoid space– contains CSF
pia mater– blood vessels and lymph
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Bell’s Palsy
Facial paralysis– functional disorder of VII cranial nerve– asthenia– keratitis– dysphasia
Treatment– anti-inflammatory drugs
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Cerebrovascular Disease
Arteriosclerosis cerebrovascular accident (CVA, apoplexy)
– ischemia– transient ischemic attack– hemiparesis– hemiplegia– aphasia– ataxia
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Seizure Disorders
Epilepsies– dysrhythmias in the brain– etiology: brain injury, congenital anomalies,
metabolic disorders, brain tumors Convulsions
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Parkinson’s Disease
Progressive neurological disorder– deterioration of portion of brain controlling
movement– bradykinesia, hypokinesia, tremors,
shuffling gait. Treatment: l-dopa
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Multiple Sclerosis
Progressive degenerative disease of CNS Inflammation, hardening, and loss of myelin
throughout spinal cord and brain Impeded transmission of electrical impulses tremors, muscle weakness, slowness of
movements etiology: autoimmune, or slow virus
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Alzheimer’s Disease Progressive neurological disorder plaques develop in cerebral cortex memory loss, cognitive decline, and
personality changes leading cause of senile dementia research: some meds prevent
breakdown of brain chemicals
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Oncology
Intracranial tumors– primary sites– metastatic sites
Signs and Symptoms– headaches– papilledema– personality changes
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Agnosia asthenia ataxia cerebral palsy closed head trauma coma concussion Guillian-Barre syndrome herpes zoster (shingles)
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Paresthesia poliomyelitis quadriplegia Reye’s syndrome sciatica syncope
– vasovagal transient ischemic attack (TIA)
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Cerebral angiography echoencephalography electroencephalography (CCG) myelography computed tomography (CT scan)
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Surgical and Therapeutic Procedures
Cryosurgery spinal puncture, spinal tap trephination vagotomy
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Pharmacology Analgesics \anticonvulsants antidepressants hyponotics opiates psychtropic drugs sedatives tranquilizers