Biological Rhythms Flashcards
What is a biological rhythm?
Cyclical changes that influence the way body behaves
Always restarts within a certain time frame.
Evolutionary
What is a circadian rhythm?
Lasts 24 hours
Regulates physical processes.
Driven by body clocks
Synchronised by SCN in hypothalamus
What is the SCN?
Master pacemaker
Must be constantly reset to be kept in synch.
What are endogenous pacemakers?
internal body clock that keep biological processes to time.
What are exogeneous zeitgebers?
External cues that alter body clocks to match environment
Describe briefly how sleep/wake cycle works?
When light detected by SCN, it sends light to the pineal gland which stops production of melatonin.
Describe study of Siffre in the cave?
Suggested that endogenous pacemakers are free-running and maintain cycles without constant entrainment of exogenous zeitgebers.
Spent 6 months in a cave with no natural light or social cues.
Findings of Siffre’s study
The body clock maintained regular cycle of around 25 hours without EZs
Suggested that biological clock free-running but to keep it at 24 hours —> needs entrainment
Criticism of cave study
use of artificial lights disrupted measurements of free-running circadian rhythm by acting as an EZ.
Czeisler found circadian rhythm closer to 24 hours when controlling for artificial light.
Vetter 2011
Evaluation points
Ralph and mutant hamsters = SCN main endogenous pacemaker
Positive implications to wider society —>medical effectiveness
Better to take aspirin at night.
provides understanding of negative consequences of desynchronisation.
Night shift workers 3x more likely to get heart disease.
Reduced concentration = more likely to make mistakes
What is an infradian rhythm?
Biological process that occurs for 24 hours.
