final

Cards (235)

  • Zeitgebers: stimuli that help establish and maintain biorhythms
  • the sun is the most important zeitgeber
  • larks = morning people
  • night owls = most adolescents
  • larks (stability) have low neuroticism, high agreeableness, and high conscientiousness
  • night owls (plasticity) have more openness and extraversion
  • the same differences in serotonergic functioning that are hypothesized to contribute to personality stability may be responsible for morningness
  • teens reflect changes in melatonin release (pineal gland)
    • after teen years, people tend to stop being night owls
    • might indicate brain maturity
  • night shifts interfere with circadian rhythm
    • 5-10% of night workers
  • jet lag is worse when traveling east
  • daylight savings
    • phase advance in fall 1 hour (west)
    • phase delay in spring 1 hour (east)
  • daylight savings time correlates with more heart attacks since sleep deprivation leads to inflammation and sympathetic activation
  • the body's master clock is the suprachiasmatic nucleus (SCN)
  • the SCN has per, tim, and clock proteins
  • the SCN is above the optic chiasm (supra)
  • SCN receives information from special cells in the retina called intrinsically photosensitive retinal ganglion cells (ipRGC)
  • ipRGC
    • no visual image processing
    • contains photopigment called melanopsin
    • contributes to pupil light reflex
  • the photopigment melanopsin chemically changes in response to light
  • SCN is only active during the day and helps distinguish between day and night
  • SCN --> SNS --> pineal gland
  • melatonin does not keep you asleep, it only helps initiate it
  • low SCN activity --> low sympathetic activity --> pineal activity rises, more melatonin
  • SCN can generate and maintain rhythms independently
    • isolated SCN tissue shows cycle
    • SCN transplantation shows original cycle
  • peripheral clocks exist but SCN is quicker
  • SCN adjusted after 1-2 cycles, lungs 6 cycles, and liver 16 cycles in rats
  • peripheral clocks are more strongly influenced by daily feeding cycles
  • SCN receives light from retina but still maintains own timekeeping mechanisms
  • per (period) gene, tim (time) gene, clock gene produce proteins
  • if high tim and per, low clock
  • if low tim and per, high clock
  • clock protein - circadian locomotor output cycles kaput
  • the 24 hour production and degradation of specific proteins enables SCN to tell time
  • clock increases tim and per
  • pineal gland dependent on SCN for circadian rhythms
  • melatonin diffuses into CSF of 3rd ventricle
  • melatonin suppressed by light, peaks at 4am
  • taking too much melatonin can lead to sleepiness during the day
  • pineal gland can disrupt hormones (testosterone and estrogen) and can interact with other medications, thinning blood
  • cortisol released by adrenal gland, promotes arousal
  • cortisol is highest in the early morning and remains in the blood for 3 hours