ch 13

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ch 13
2011-05-03 16:32:13

peripheral nervous system
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  1. sensation
    a state of awareness of internal or external conditions
  2. perception
    conscious registering of a stimulus/sensation
  3. a sensation requires
    • 1) stimulus
    • 2) receptor/sense organ
    • 3) conduction
    • 4) translation
  4. conduction
    get the stimulus to the brain
  5. translation
    convert stimulus into a sensation
  6. characteristics of sensation
    • projection
    • modality
    • adaptation
    • afterimage
  7. projection
    the brain can put a location on its origin
  8. modality
    sensations can be distinguished/separated from one another
  9. adaptation
    reduction/dissapearance of a sensation, even though the stimulus is still being applied
  10. afterimage
    persistance of a sensation, even after the stimulus is removed
  11. sensory receptors
    can be classified by location, type of stimulus, or complexity
  12. location
    extero, intero, viscero receptors
  13. proprioreceptor
    change in body part position
  14. mechanoreceptors
    • change in shap of receptor or nearby cells
    • respond to physical deformation-
    • ex. baroreceptors - blood vessels
    • hair cells- hearing & equilibrium
  15. thermoreceptors
  16. photoreceptors
  17. nociceptors
    pain (free nerve endings)
  18. chemoreceptors
    changes in chemical levels (taste & smell)
  19. general senses
    • simple receptors & pathways:
    • touch
    • pressure
    • heat
    • cold
    • pain
  20. special senses
    taste, smell, vision, hearing, equilibrium
  21. 12 pair
    • 10 originate in the brain stem
    • 1 originates in olfactory mucosa
    • 1 originates in retina of eye
  22. motor:
    oculomotor, accesory, trochlear, hypoglossal, abducens
  23. sensory:
    olfactory, optic, and vestibulochochlear
  24. mixed:
    trigeminal, facial, glossopharyngeal, vagus
  25. spinal nerves
    • 31 pair, all are mixed
    • 2 roots

    each branches shortly after leaving vertebrae
  26. dorsal root
    sensory; has ganglion containing cell bodies of sensory neurons
  27. anterior/ventral
    motor (no ganglion)
  28. rami, ramus (singular)
    branches of spinal nerves
  29. dorsal rami
    innervate the deep muscles and skin of the back
  30. ventral rami
    innervate everything else, but dont go directly to areas they innervate- they first form plexuses
  31. plexuses
    networks with adjacent nerves
  32. cervical plexus
    • involves C1-C4 and part of C5
    • innervates head, neck, upper shoulder
    • has motor fibers to diaphragm
  33. brachial plexus
    involves C5-C8; part of T1

    innervates upper extremities & rest of shoulders
  34. lumbar plexus
    involves L1- L4(part)

    innervates wall of abdomen, skin of external genitalia, part of lower extremities
  35. sacral plexus
    involves L4-L5, S1-S4

    innervates buttocks, perineum, most of lower extremities
  36. thoracic nerves
    • generally do not form plexuses
    • innervate the intercostals, chest wall, armpit, part of the arm & part of abdominal muscles
  37. dermatomes
    specific segments of skin innervated by specific spinal nerves
  38. reflex
    automatic, unlearned motor response to a stimulus
  39. component of reflex arc
    • 1) receptor
    • 2) sensory neuron
    • 3) integration center
    • 4) motor neuron
    • 5) effector
  40. stretch reflex
    • monosynaptic
    • receptor muscle spindle
    • ipsilateral
  41. ipsilateral
    both sensory & motor impulses originate on the same side of the cord
  42. reciprocal activation
    we relax the muscle that is the antagonist of the one that contracts
  43. tendon reflex
    • polysynaptic
    • receptor
    • ipsilateral
  44. flexor reflex
    • withdrawl
    • polysynaptic
    • receptor = nociceptor
    • ipsilateral
  45. crossed extensor reflex
    • polysynaptic
    • contralateral
    • receptors: various proprioceptors
    • ex: shifting weight to avoid a fall
  46. contralateral
    sensory impulses on one side of the cord bring about motor responses from the other side
  47. motor impulse resulting in flexion are sent to stimulated area; motor impulses resulting in extension are sent to the opposite side of the body