circadian rhythms

• What are biological cycles in the body?

  Predictable cycles occurring at various intervals
• How often do some biological cycles occur?

  Some occur many times a day, others take weeks
• What is an endogenous pacemaker?

  An internal body clock that keeps time
• What does the term 'exogenous' refer to in exogenous pacemakers?

  It means outside
• What is the role of exogenous pacemakers?

  They provide environmental cues to regulate time
• What is another term for the process of entrainment?

  Adjusting internal clocks to external cues
• What is a circadian rhythm?

  A biological rhythm lasting around 24 hours
• What is the most obvious circadian rhythm?

  The sleep/wake cycle
• How does light affect the sleep/wake cycle?

  It influences melatonin production in the body
• What happens during jetlag in relation to pacemakers?

  Conflicts arise between external cues and internal clocks
• What is the SCN in relation to the sleep/wake cycle?

  It is the master clock in the hypothalamus
• How does the SCN respond to light?

  It detects light and regulates melatonin production
• What hormone does the pineal gland produce?

  Melatonin
• What is the effect of light on melatonin production?

  Light suppresses melatonin production
• What evidence supports the existence of a free-running circadian pacemaker?

  Studies of individuals isolated from light
• What did Siff's study in a cave demonstrate?

  Body clock extended to around 25 hours
• What criticism exists regarding Siff's study methodology?

  Participants controlled artificial light usage
• What did recent work by Caesar suggest about the endogenous pacemaker?

  It is capable of a precise 24-hour rhythm
• What did the 2011 study on blue light exposure find?

  It affected circadian rhythms in office workers
• What happens when the SCN is destroyed in hamsters?

  They exhibit a 20-hour circadian rhythm
• What does Ralph's experiment with hamsters demonstrate?

  SCN is the endogenous pacemaker for sleep/wake cycle
• What are the implications of understanding circadian rhythms?

  It can improve treatments for jetlag and productivity
• How does exposure to blue light affect sleep?

  It disrupts natural sleep patterns
• What is chronobiology?

  The study of biological rhythms
• How do some species adapt their circadian rhythms in extreme environments?

  They can turn off their circadian rhythms
• What is a unique characteristic of arctic reindeer regarding circadian rhythms?

  They lose circadian rhythm in summer
• What is the significance of the study on a blind man regarding circadian rhythms?

  He had a 24.9-hour rhythm despite social cues
• Why is it evolutionarily advantageous for humans to have a day/night cycle?

  It aligns with daytime activity for survival
• What is a characteristic of nocturnal animals regarding their circadian pacemaker?

  It is shifted to be active at night
• What is the impact of technology on circadian rhythms?

  Increased exposure to blue light disrupts sleep
• How can understanding circadian rhythms benefit health services?

  It aids in timing drug treatments effectively