Lecture PNS

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  1. Sensory receptors classified by stimulus type
    Mechanoreceptors: respond to touch, pressure, vibration, stretch, and itch

    thermoreceptors: sensitive to change in tempertature

    photoreceptors: respond to light energy (retina)

    chemoreceptors: responds to chemicals (smell, taste, changes in body chemistry)

    nociceptors: respond to pain causing stimuli
  2. snesory receptors classified by location
    • 1. Exteroceptors: respond to stimuli arising outside the body
    • - most special sense ograns

    • 2. Interoceptros
    • -respond to stiumuli arising in internal viscera and blood vessels
    • -sensitive to chemical changes, tissue stretch, and temp changes

    • 3. Proprioceptors
    • -respond to stretch in skeletal muscles, tendons, joints, ligaments, and connective tissue cvering bones and muscles
    • -inform brain of bodys movments
  3. Unencapsulated dendritic endings
    • 1. thermoreceptors
    • 2. nociceptors
    • 3. light touch receptors
    • -Merkel discs (deep layers of epidermis)
  4. encapsulated dendritic endings
    *All are mechanoreceptors*

    1. Meissner's corpuscles: discriminative touch (dermal papillae)

    2. Picinian (lamellated) corpuscles: deep pressure and vibration (dermis and subcutaneous tissue)

    3. Ruffini endings: deep continuous pressure (dermis, subcutaneous tissue, and joint capsules)

    4. Muscle spindles: muscle stretch (perimesium of muscle tissue)

    5. Goldi tendon organs: stretch in tendons

    6. Joint kinesthetic receptors - stretch in articular capsules
  5. Aspects of sensory perception
    perceptual detection: ability to detect a stimulus (Requires summation of impulses)

    magnitude estimation: intensity is coded in the frequency of impulses

    spatial discrimintation: identifying the site of pattern of the stimulus (studied by 2 point discrimination test)

    feature abstraction: indentification of more complex aspects and several stimulus properties

    quality discrimination: the ability to identify submodalities of a sensation (sweet vs sour)

    pattern recognization : recognition of familiar or significnat patterns in stimuli (like the melody in a piece of music)
  6. Regeneration of nerve fibers
    • 1. the axon becomes fragmented at the injury site
    • -Walerian degeneration

    2. macrophages clean out the dead axon distal to the injurt

    3. axon sprouts, or filaments, grow through a regeneration tube formed by schwann cells

    4. the axon regenerates and a new myelin sheath forms
  7. Hiltons law
    • •Hilton’s law: Any nerve
    • serving a muscle that produces movement at a joint also innervates the joint
    • and the skin over the joint
Card Set:
Lecture PNS
2012-05-04 14:55:36
PNS lccc bio 163

PNS lccc bio 163
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