Circadian rhythms

• What are the biological cycles in the human body described in the study material?

  They occur predictably, some many times a day, some once every 24 hours, and some take weeks or years.
• What is an endogenous pacemaker?


  An endogenous pacemaker is an internal body clock that helps keep track of time.
• What does the term "exogenous zeitgeber" refer to?


  An exogenous zeitgeber is an environmental cue from the outside world that helps regulate the internal body clock.
• What is the process of entrainment?


  Entrainment is the process by which external cues synchronize the internal body clock.
• What is the definition of circadian rhythm?


  A circadian rhythm is a biological rhythm that lasts around 24 hours.
• What are some examples of circadian rhythms mentioned in the study material?


  Examples include the sleep/wake cycle, hormone release, and body temperature variations.
• How do exogenous zeitgebers affect the sleep/wake cycle?


  They provide cues like light and social interactions that help regulate the internal body clock.
• What is the role of the suprachiasmatic nucleus (SCN) in the sleep/wake cycle?


  The SCN is the master clock that regulates the sleep/wake cycle based on light exposure.
• Where is the SCN located?


  The SCN is located in the hypothalamus within the limbic system.
• How does light affect melatonin production?


  Light suppresses melatonin production, making you feel less sleepy.
• What is the significance of the research conducted by Siff regarding circadian rhythms?


  Siff's research showed that the endogenous biological rhythm can maintain itself without external cues.
• What did Siff's study in the cave demonstrate about the human body clock?


  It demonstrated that the body clock can extend beyond the normal 24-hour cycle to around 25 hours.
• What criticism has been raised regarding studies on circadian rhythms conducted in artificial light conditions?


  Critics argue that participants may alter their biological clock with the use of artificial lights.
• What did the research by Caesar suggest about the endogenous pacemaker?


  Caesar's research suggests that the endogenous pacemaker is precise and capable of maintaining a 24-hour rhythm.
• What did Ralph's experiment with hamsters demonstrate about the SCN?


  Ralph's experiment showed that the SCN is the endogenous pacemaker responsible for the sleep/wake cycle.
• What are the implications of understanding circadian rhythms for health services?


  Understanding circadian rhythms can help in timing drug treatments and improving health services.
• How does exposure to blue light at night affect circadian rhythms?


  Exposure to blue light at night can disrupt circadian rhythms and affect sleep quality.
• What did the study on a blind man reveal about circadian rhythms?


  The study showed that even with social cues, the blind man had a circadian rhythm of 24.9 hours, indicating a lack of synchronization with society.
• What is chronobiology?


  Chronobiology is the area of research focused on biological rhythms.
• How can circadian rhythms be affected by environmental conditions?

  Circadian rhythms can be turned off in certain conditions, such as during the Arctic summer when the sun never sets.
• What adaptations do migrating birds have regarding their circadian rhythms?


  Migrating birds can turn off their circadian rhythms for weeks to facilitate their journey.
• What are the key components of the circadian rhythm system?

  • Endogenous pacemakers (internal body clocks)
  • Exogenous zeitgebers (external cues)
  • Suprachiasmatic nucleus (SCN) as the master clock
  • Hormonal regulation (e.g., melatonin)
• What are the implications of circadian rhythm research for various fields?


  • Treatments for jetlag
  • Improved performance for athletes
  • Enhanced productivity for shift workers
  • Timing of drug treatments in health services