chapter 4 and 5?

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chapter 4 and 5?
2013-11-08 02:24:46
442 Neuro

442 Neuro
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  1. somatic senses 1: the anterolateral system
    somatic senses
    the senses of touch, temp body position and pain
  2. what are the senses associated with
    • receptors in the skin, muscles, joints, and viscera (internal organs of the body especially of the thorax and abdomen, as the heart, lungs, kidneys, intestines etc...
    • relates to structures derived from a series of mesodermal somites, including skeletal muscles
  3. somite
    a segmental block like mass of mesoderm (middle layer of skin) on either side of notochord, gives rise to muscles, vertebral and skin
  4. mesoderm
    • middle of three primary germ layers
    • midline strip of cells sandwiched between the endoderm and ectoderm
  5. notochord
    primitive, solid, skeletal structure derived from specialized mesodermal cells that is retained in intervertebral disk as nucleus pulposus and lies ventral to neural tube
  6. what are two receptor types
    • 1. thermoreceptors-receptors sensitive to temp, respond to change in temp and are located in the skin
    •    -hot and cold receptors are separate and are not distributed evenly across the skin (approx 1 mm wide)
    • 2. nociceptors-(nocere means to hurt) receptors which respond to tissue damage (pain receptors)
    •     -serve as body's warning system
  7. what do thermoreceptors and nociceptors have in common
    both are free afferetn nerve endings, take info from skin surface to brain
  8. what are some other receptors?
    • mechanoreceptors -respond to mechanical pressure or deformation of the receptor and adjacent tissues
    • photoreceptors- respond to light directed on the retina of the eye
    • chemorecepotors-respond to taste and smell
  9. what helps sensory receptors to monitor internal and external environment
  10. difference between initial and secondary pain
    • initial pain is fast and sharp
    • secondary pain is achy and slow and runs along the nerve
  11. where is the body (soma) of the sensory receptors
    • in the dorsal root ganglia of neurons
    • these are clusters that lie outside of the spinal cord
  12. first order neurons
    1st in line to receive info from the periphery and transmit it to the second order neurons
  13. pseudounipolar
    an axon process dividing into two branches, one extending into the periphery, and another central branch that extends into the spinal cord (2 axons)
  14. what happens when primary afferent (first-order) neurons are in action
    • 1. terminal of the peripheral branch transduces stimulus energy from a sensory receptor
    • 2.  the signal is transmitted as an action potential along the peripheral bran and its continuation in the central branch
    • 3.  primary afferent fiber: both branches together (peripheral and central), terminates on a sensory neuron in the dorsal horn on the spinal column (second order neuron)
  15. what are the two types of afferent fibers that convey pain and temp to the spinal cord
    • a-delta fibers
    • c fibers
  16. what are the a-delta and c fibers classified by
    • 1. conduction velocity of the action potential (along the fiber to the nervous system)
    • 2. aspects of the stimulation that must occur to evoke a response (ex-intensity, (strength), duration (length), and quality (clarity)
    • 3. characteristic responses of the nociceptor to natural stimuli (ex-slow v fast adaptation)
  17. primary afferent neuron:
    • lightly myelinated 
    • important because we need to speed up the info
  18. what is a-delta stimulated by
    • by low threshold meaning that it doesn't take much to activate, superficial receptors
    • associated with pain that has a sharp, pricking quality and can be localized on the body surface and diminishes quickly
    • fast pain, initial pain, first pain
  19. c-fibers
    • unmylinated
    • stimulated by high-threshold receptors
    • convey diffuse, persisting pain that we perceive as:
    • aching, throbbing, burning pain that is poorly localized 
    • called slow pain, delayed or second pain
    • found to be intolerable relative to the initial stabbing pain conducted by a-delta fibers, which can often preceed slow pain
  20. how are thermal nocicepctors for cold connected to the spinal cord
    a delta fibers
  21. painful sensations from heat activate the...
    c fibers
  22. polymodal nociceptors activate...
    • this is where you are hit by a hard ball and then fell the pain afterwards
    • c fibers