endogenous pacemakers and exogenous zeitgebers L11

• What are endogenous pacemakers?

  Internal biological clocks
• What are exogenous zeitgebers?

  Environmental events that affect the biological clock
• What is the role of the suprachiasmatic nucleus (SCN) as an endogenous pacemaker?

  • Acts as the "master clock" in the hypothalamus
  • Controls circadian rhythms on a 24-hour cycle
  • Receives light information via the optic nerve
  • Regulates other pacemakers in the body
• What did Morgan (1995) demonstrate with hamsters regarding the SCN?

  He showed that the SCN controls circadian rhythms
• How does light affect the biological clock according to the study?

  Light resets the biological clock each day
• What happens when SCN neurons from normal hamsters are transplanted into abnormal hamsters?

  The abnormal hamsters change to a normal 24-hour circadian rhythm
• What hormone does the pineal gland produce at night?

  Melatonin
• How do social cues influence our circadian rhythm?

  They promote wakefulness and regulate sleep patterns
• What effect does artificial light at night have on circadian rhythms?

  It can disrupt the circadian rhythm
• What did Toniton et al. (2017) find about teenagers and electronic media?

  Teenagers spend increasing amounts of time on electronic media at night
• How does blue light from LED bulbs affect melatonin secretion?

  It leads to suppression of melatonin secretion
• What are the long-term effects of sleep deprivation in adolescents?

  It can lead to increased rates of cardiovascular and mood disorders
• What role does melanopsin play in circadian rhythms?

  • Important for setting the circadian rhythm
  • Found in specialized light-detecting cells in the retina
  • Helps gauge light levels and send signals to the SCN
• What did Skene and Arendt (2007) estimate about blind people with light perception?

  Most have normally entrained circadian rhythms
• How do peripheral pacemakers relate to the SCN?

  The SCN regulates peripheral pacemakers in the body