1. layers of median eminence
    • third ventricle
    • ependymal layer: tanycytes (astrocytes)
    • internal layer: axons of hypothalamohypophyseal tract from paraventricular, median supraoptic tracts
    • external layer: nerve terminals of neurosecretory neurons
    • perivascular layer: tissue into which hypophyseal hormones are released before entering hypophyseal portal system (superior hypophyseal artery, branch of posterior communicating)
  2. hypophyseal portal system
    • superior hypophyseal artery: supplies primary capillary network in pituitary stalk, median eminence
    • long hypophyseal portal veins: connect it to secondary capillary network within adenohypophysis
  3. intermediate lobe of pituitary
    • pars intermedia
    • colloid follicles
    • produce POMC (ACTH precursor)
  4. ddx short stature
    • normal height variation
    • pituitary dwarfism
    • in utero effects
    • emotional deprivation
    • chronic disease
    • drug effects e.g. asthma
    • malnutrition
  5. in utero growth effects
    • largely independent of fetal and maternal hormones
    • O2/nutrient supply from placenta
    • intrauterine infections
    • toxins
    • genetic factors
    • IGF1/2
    • influence on later growth, metabolism
  6. growth mechanisms by phase
    • in utero and infancy: in utero conditions
    • childhood: GH
    • puberty: GH, sex hormones
  7. average height difference adult male and female
  8. ddx acromegaly
    • 1. pituitary tumour
    • 2. hypothalamus tumour
    • 3. small cell lung ca
  9. GH workup
    • 1. igf1
    • 2 gh suppression test
  10. embryonic establishment of CNS
    • week 3: gastrulation forming trilaminar disc
    • week 4: neurulation - differentiation of ectoderm to form neural plate; embryonic folding and neural folding to form neural tube
    • neural tube: CNS and brain
    • neural crest (peripheries): PNS
  11. neural tube defects
    • failure of neuropore to close during neural folding
    • day 26: closure anterior neuropore (anencephaly, encephalocele)
    • day 28: closure posterior neuropore (spina bifida)
  12. RDI folate
    • 400 micrograms per day
    • more if: clomifene, carbemazepine, DM1, obese, fam hx NTD
  13. long term potentiation
    • model for associative conditioning aka learning and memory
    • summation of EPSP overtime to reach threshold for LTP causing insertion of more AMPA receptors and splitting or membranes, formation of new synapses
    • increased excitatory response for same stimulus
  14. GBS
    • AI demyelination usually following infection
    • rapidly ascending symmetrical weakness in CST and CBT
    • dx by antibody testing
    • tx IV Ig
  15. ALS
    most commonly LMN degeneration
  16. factors affecting resting tone
    • muscle structure and tissue properties
    • tonic activity in stretch reflex arc
    • incomplete relaxation
  17. neurogenic atrophy
    • aka denervation atrophy, seen in LMN
    • successive renervation of larger groups of muscle fibres as LMNs degenerate
    • eventual death and atrophy of myocytes by proteolysis
  18. tectospinal tract
    • superior colliculus
    • directs rapid orientation towards moving objects (tracking)
  19. reticulospinal tract
    • reticular formation
    • consciousness and successful locomotion
  20. vestibulospinal tract
    • vestibular nuclei
    • head position and acceleration
  21. dopamine pathways
    • nigrostriatal: substantia nigra to striatum for disinhibitory modulation (reduced in Parkinsons)
    • mesolimbic: ventral tegmental area to nucleus accumbens (pleasure pathway thought to be overactive in psychosis)
    • mesocortical: ventral tegmental area to prefrontal cortex (executive functioning)
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