sleep - endogenous pacemakers, exogenous zeitgebers

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  • Sleep
    • endogenous pacemakers
      • suprachiasmatic nucleus (SCN)
        • Tiny clusters of nerve cells - in hypothalamus
          • above optic chiasm (optic nerve cross over)
            • info about light - from eyes - via optic nerve
              • automatic shifts
                • pair of structures - one hemisphere - ventral and dorsal
                  • ventral quickly reset by external clues
                    • dorsal less effective - more resistant to being reset
      • the penal gland and melatonin
        • SCN siginals to the pineal gland to increase malatonin at night
          • induces sleep - inhibits brain mechanism
            • lizards - third eye - top of skull - receives light info
      • SCN demonstrated in animal studies
        • mutant rats - 20hrs
          • transplanted SCN into hamsters - had mutant rats rhythm
      • body's separate oscillators can desyncronise from SCN
        • kate aldcroft - cave
          • temp 24hr rhythm
            • sleep 30hr cycle
              • desynchronized rhythm similar to jet lag
    • exogenous zeitgebers
      • entrainment
        • resseting biological clock
          • opposite to free running
      • light
        • dominant zeitgebers
          • can reset SCN and other oscillators in the body
            • protein CRY is light sensitive
      • shin light on back of knee
        • circadian rhythm shifted
      • artifician lighting does have an effect
        • circadian rhythms can be entrained by artificial light
      • exposure to artificial lighting disrupts circadian rhythms and the production of melatonin
        • women in industrialized societies more likely to develop breast cancer
      • social clues
        • biologists thought social clues were the main zeitgebers for circadian rhythms
          • eat meals at socially determined times
            • all parts of the body have own oscillating rhythms
              • liver and heart likely to be reset from eating
      • temperature
        • cold blooded animals
          • clod temp time to rest
            • warm temp time for activity
              • changes in body temp - governed by circadian clock
                • temp changes entrain other circadian rhythms
    • the ticking of the biological clock
      • mutilation in genes
        • familial advanced sleep-phase syndromedefect in the PER genes
      • morning, two proteins, clock and cycle (CLK-CYC) bind
        • CLK - CYC produce period and time (PER -TIM)
          • PER - TIM render CLK - CYC inactive
            • therefore PER - TIM start to decrease (negative feedback)
              • loop last 24hrs
      • animal studies
        • issues of harm to animals
          • cant be generalized to humans
            • important to check findings against human research
      • the blended system
        • the running of the biological clock is combined endogenous - exogenous exercise
  • the blended system
    • the running of the biological clock is combined endogenous - exogenous exercise




This is really clear and easy to use. Thanks 

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