Saturday, March 12, 2011

Neurosensory Systems and Tests

  • Neuron - nerve cell -
    • axons carry away
    • dentrites bring to
    • neurotransmitters - help conduct impulses across the synapse
      • acetylcholine
      • seotonin
      • dopamine
      • endorphins
      • gamma-aminobutyric acid
      • norepinephrine
  • CNS - central nervous system - brain and spinal cord
  • Cerebrum - largest part of the brain 
    • hemispheres - right and left opposite control because motor impulses cross in the deulla
    • fissures divide cerebrum into 4 lobes
      • frontal - personality, memory, reasoning, concetration and motor control of speech
      • parietal  - sensation, integration of sensory information and spatial relationships
      • temporal  - hearing, speech, memory, and emotion
      • occipital - vision and involuntary eye movements
  • Thalamus - 2 oval shaped parts deep in the brain, the relay station - recieves input form all senses except smell, analyses input and transmits to other parts of the brain.
  • Hypothalamus - beneath the thalamus - control sleep and wakefulness, temperature, respiration, BP, sexual arousal , fluid balance, and emotioal response.
  • Cerebellum - base of the brain - coordinates muscle movements, maintains balance and controls posture
  • Brain Stem - connects brain and spinal cord has 3 sections
    • midbrain - pupillary relexes and eye movements; relfex center of the 3rd and 4th cranial nerves
    • pons - helps regulate respiration, mediates chewing, tasting, saliva and equilibruim; reflex center for the 5th, 6th, 7th and 8th cranial nerve
    • medulla oblongata - vomiting, vasomotor, respiratory and cardiac centers
  • Spinal cord - 2 way conduction system between brain and peripheral nervous system (PNS)
    • gray matter - cell bodies and dendrites and axons
    • white matter ascending (sensory) sends signalsto the brain and desending (motor) tracts send signals out to the muscles
  • PNS - Periperal Nervous System - delivers messages (like the post office) main nerves grouped
    • 31 pairs of spinal nerves - carry mixed impulses (motor and sensory)
    • 12  pairs of cranial nerves -
      1. olfactory
      2. optic
      3. oculomotor
      4. trochlear
      5. trigeminal
      6. abducen
      7. facial
      8. acoustic
      9. glossopharyngeal
      10. vagus
      11. spinal accessory
      12. hypoglossal
    • Autonomic nervous system - subdividsion of PNS - controls involuntary body functions
      • digestion
      • respiration
      • cardiovascular
        • 2 cooperating systems
          • sypathetic - fight or flight
          • parasympathetic - conserves and restores energy
  • Eyes -
    • external -
      • eyelids
      • conjuctivae (thin transparent membrane that line the lids)
      • lacrimal apparatuses,extraocular muscles, and the eyeballs
    • internal -
      • iris
      • cornea
      • pupil
      • lens
      • vitreous humor
      • retina
      • retinal cones - visual acuity and color discrimination under bright lights
      • retinal rods - peripheral vision under decreased light conditions
      • optic nerve - 2nd cranial nerve
  • Ears
    • External -  pinna (auricle) and external auditory canal separated by the tympanic membrane
    • Middle -  AKA tympanum - air filled cavity in the temporal bone - 3 small bones - malleus, incus, and stapes
    • Inner - AKA Labyrinth - cochlea, vestibule and semicircular canals
Most Important Tests
  • Electroencephalogram (EEG) electrical graph of brain activty
  • Computer tomography (CT) - cross scetion veiws of brain images
  • Magnetic Resonance Imaging (MRI) - magnetic snapshot - contraindications - pacemaker
  • Cerebral Angiogram - upstairs artery exam blood flow using dye
    • check site for bleeding
    • assess distal pulses
    • assess neuro status
    • encourage fluids
  • Lumbar Puncture L(P) - reveals pressure also used to inject dye for myelogram *contra indicated with increase intracranial pressur (ICP)
    • keep flat
    • monitor neuro status
    • monitor site for leakage or bleeding
    • encourage fluids
  • Cerebrospinal fluid (CFS) analysis - LAB
  • Electromypgraphy (EMG) - electrical acitivity of a muscle at rest and contraction
  • Myelography - see the spine - subarachnoid space, spinal cord and verebrae contraindicated with seafood or iodine allergies
    • keep flat after
    • check site for leakage or bleeding
    • encourage fluids
  • Skull x-ray
  • Positron emission tomography (PET) injection of radioisotope after visulaization of the brain's oxygen uptake, blood flow and glucose metabolism
    • no tobacco, alcohol,  or caffeine 24 hours before
  • Blood Chemestry Test - checking levels of potassium, sodium, calcium, phoshorus, protein, osmolality, glucose, bicarbonate, blood urea nitrogen and creatinine
  • Hematologic study - WBCs, RBCs, erythrocyte sedimentation rate, platelets, hemoglobin, hematocrit.
  • Coagulation study
  • Visual Acuity
  • Extraocular eye muscle testing - checks for parallet alignment of the eyes, muscle strength and cranial nerve function
  • Visual field examinaitn
  • Tonometry test - measures intra ocular pressure
  • Tick-tock test is an auditory acuity test checking ability to hear a whispered phrase or a ticking watch
  • Otoscopic examination to visulize the tympanic membrane
  • Audiometry - measures degree of deafness

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