Biological Rhythms Flashcards
What does endogenous mean?
Something that’s built in
What does exogenous mean?
Something that affects us on the outside (environment)
How often does a circadian rhythm repeat itself?
Every 24 hours
How often does a ultradian rhythm repeat itself?
More than once in 24 hours
How often does a infradian rhythm repeat itself?
In a period over 24 hours
Why did Siffre spend 2 months in a dark cave?
Wanted to see whether the sleep wake cycle depends mainly on exogenous or endogenous factors
What happened to Siffre in the cave?
No clear pattern was established initially but after a while he settled to a clear 25hr pattern
What can we conclude from siffre’s study?
Proves we get affected by exogenous factors as when they were changed (dark cave) his s/w cycle changed
What is entrainment?
When our biological and environmental factors are in line with one another
Why was Siffre’s study not universal?
Can’t apply it to other as it could be affected by individual differences. For example as Siffre AGEd his clock slowed
What is the SCN?
The main pacemaker for circadian rhythms
What does the SCN do?
Controls levels of melatonin via the pineal gland
Support for the SCN’s role in the SWC comes from hamsters
Transplant SCN of mutant 20hr cycle hamsters to normal hamsters, ‘normal’ hamsters adapted to that cycle and returned back to normal when replaced with the original
What is an exogenous zeitgeber?
Factor outside our body which may trigger biological rhythms
Siffre found that an important exogenous zeitgeber is…
Light
What does siffre’s research suggest about zeitgebers?
They’re needed to keep our rhythms in sync
Outline how Miles’ study highlights the deterministic nature of biological rhythms
Told 12 students, for 3 weeks, to sleep at 11:45 and wake at 7:45. He sped this up so they only had a 22hr cycle, 1 followed but the rest stuck to their 24hr cycle. Shows how speeding up a cycle doesn’t affect everyone
Evidence that we can ‘will’ our biological rhythms come from where?
When told to wake earlier than usual we have an increase in the stress hormone ACTH which makes us wake earlier
DeCoursey outlines the adaptive reasons why rhythms are determined, explain this
Bio rhythms allow animals to justify daily environmental events. Chipmunks SCN removed - most died after 80 days as they remained awake at night and so weasels could hear them
Why can you justify the ethical implications of DeCoursey’s research?
It has lots of real-life application so testing on animals is not too bad
