Circadian Rhythms Flashcards
What are two examples of circadian rhythms?
Sleep/wake cycle
Core body temperature
What is a circadian rhythm?
Internal processes of the body that follow a 24-hour cycle
How is the sleep/wake cycle maintained?
-Light detected by the eye
-This information is sent to the suprachiasmatic nucleus (SCN)
-SCN regulates the circadian cycle
What are endogenous pacemakers?
Internal body clocks that keep biological processes to time
What are exogenous zeitgebers?
External cues that influence internal biological rhythms
What are some examples of exogenous zeitgebers?
-Social cues
-Light
How does the suprachiasmatic nucleus wake us up?
-Light is detected by the eye
-Infomation sent to the SCN
-SCN sends a signal to the pineal gland
-Pineal gland stops the production of melatonin
Where is the SCN?
Hypothalumus
What did Siffre find about circadian rhythms?
-siffre spent 200 days in a cave without natural light or any exogenous zeitgebers
-His body maintained a 25 hour sleep/wake cycle
What does siffre’s findings tell us about circadian rhythms?
The endogenous pacemakers for the sleep wake cycle is free running but we need Exogenous zeitgebers to keep to 24 hours.
What is a limitation of explaining circadian rhythms as 24 hours?
Duffy et al found individual differences may cause different sleep/wake cycle times
-Some people go to sleep later and wake up later, may be innate differences
What is a limitation of siffre’s research?
-It was a case study of only one person
-Finding may not be representative of the wider population
What did Morgans research find?
-Bred hamsters with a circadian rhythm of 20 hours
-This SCN was implanted into normal hamsters and the normal hamsters soon had a 20 hour rhythm
What does Morgans research tell us?
The significance of the SCN and how endogenous pacemakers are important for circadian rhythms
What is melanopsin?
A protein in the eye is sensitive to light and carries signals to the SCN
