Neuro Exam2.1.txt

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Neuro Exam2.1.txt
2011-04-04 02:43:09
Neuro Exam2

Neuro Exam2.1
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  1. When does gastrulation begin?
    • by day 15
    • formation of primitive streak on post. surface of epiblast
    • establishes trilaminar disc-ectoderm, mesoderm, endoderm
  2. When does neurulation begin?
    • by day 17
    • notochord derived from epiblast (mesoderm)
    • notochord induces ectoderm to form neural plate
    • neural plate becomes neural groove then neural tube
    • neural tube forms brain and spinal cord
    • neural crest cells arise adjacent to neural tube
    • cranial (rostral) neuropore closes by day 25
    • caudal neuropore closes by day 27
  3. what happens early in week four that relates to eye developement?
    • prior to cranial neuropore closure
    • two optic grooves from on the sides of the forebrain
  4. what happens late in week four that relates to eye developement?
    • optic grooves form outpocketings of the forebrain call optic vesicles
    • come in contact with surface ectoderm and induce formation of lens placodes
    • happens with neuropore closure
  5. what happens in week five that relates to eye developement?
    • optic vesicle and lens placode invaginate
    • optic vesicle forms a double-walled optic cup with inner(neural) layer and outer(pigmented) layer
  6. what happens in week six that relates to eye developement?
    • optic stalk connects optic cup to forebrain
    • lens vesicle loses contact with surface ectoderm and lies in mouth of optic cup
    • optic stalk becomes optic nerve
  7. Embryonic origins of structures of the eye:
    • Surface ectoderm: lens
    • Neural ectoderm: vitreous body, sphincter pupillae and dilator pupillae muscles, optic nerve
    • Mesoderm (Neural Crest): sclera, stroma of cornea, ciliary body, iris choroid
  8. PAX6
    Master gene for eye developement-regulates differentiation of optic cup and lens
  9. SHH
    • secreted by prechordal plate
    • inhibits PAX6 expression in midline
    • upregulates PAX2 expression in the midline
  10. PAX2
    regulates differentiation of the optic stalk
  11. Which cells have a concentric center-surround receptive field?
    • bipolar cells
    • ganglion cells
    • LGN cells
    • granule cells
  12. types of cells in primary visual cortex
    • granule cells
    • simple cells
    • complex cells
  13. Posterior Column-medial lemniscus system (PCMLS)
    discriminative touch (2-point localization), vibratory sense, conscious proprioception from the body
  14. Anterolateral System (ALS)
    pain, temperature, crude touch sensation from the body
  15. Trigeminal pathways
    all types of sensation from the face
  16. Spinocerebellar pathways
    non-conscious proprioceptive information to the cerebellum
  17. somatosensory receptors
    • mechanoreceptors
    • proprioceptors
    • nociceptors-pain
  18. primary sensory neuron
    • pseudounipolar
    • peripheral process
    • cell body (PRG or trigeminal ganglion)
    • central process enters spinal cord or brainstem
  19. secondary neuron
    in spinal cord or brain stem
  20. tertiary (3*) neuron
    in thalamic nucleus
  21. types of mechanoreceptors
    • encapsulated: meissner's corpuscle, pacinian corpuscle, ruffini corpuscle
    • non-encapsulated: merkel cell neurite complex(hair follicle), free nerve endings
  22. nociceptors
    • all free nerve endings:
    • mechanonociceptors
    • themonociceptors
    • chemonociceptors
  23. Nociceptors: peripheral (primary hyperalgesia)
    • occurs at receptor
    • decreased threshold, increased firing rates at lower thresholds
    • axon reflex: release of NTs and neuropeptides (substance P) from sensory ending, inflammatory response
    • (sun burn)
  24. Nociceptors: central (secondary hyperalgesia)
    • increased excitability of A-delta and C-type fibers
    • neuropathic pain (allodynia)
  25. PCMLS (posterior column-medial lemniscus system) pathway
    • primary neuron: peripheral process, cell body in PRG, central process from fasciculus gracilis and fasciculus cuneatus, synapse in caudal medulla
    • secondary neuron: nucleus gracilis or nucleus cuneatus, axon decussates to contralateral medial meniscus, synapse in thalamus
    • tertiary neuron: ventral posterolateral nucleus (VPL) of thalamus, posterior limb of internal capsule, primary sensory cortex (SI)
  26. PCMLS: primary sensory cortex submodalities
    • 3a, 2 - proprioceptive inputs
    • 3b, 1 - cutaneous mechanoreceptors
  27. PCMLS primary sensory cortex
    • S1
    • postcentral gyrus (lateral)
    • posterior paracentral gyrus (medial)
    • Brodmann areas 3, 1, 2
  28. PCMLS secondary cortical processing sites
    • parietal association complex
    • Brodmann areas 5, 7
    • Secondary somatosensory cortex (SII)
    • lesion = astereognosis (inability to identify objects by touch)
  29. PCMLS blood supply?
    • middle cerebral artery
    • anterior cerebral artery