Biological Rhythms Flashcards
What does the SCN control?
Urine secretion Respiration Heart rate Sleep/wake cycle Body temperature
Identify and explain two evaluation points to do with methodology for the role of exogenous pacemakers
Use of animals -
Can’t generalise
Can harm animals so it needs to be justified
Reductionist -
Too oversimplified
Need to look at the interaction between exogenous zeitgebers and endogenous pacemakers.
What’s the main exogenous zeitgebers?
Light
Are exogenous zeitgebers internal or external?
External
What two things did Morgan’s study include?
Took SCN out of hamsters and the circadian rhythm disappears
Took the 20 hour circadian rhythms out of mutant hamster and put them in normal hamsters. The hamsters then displayed the rhythms
…support for SCN being he main endogenous pacemaker
Are endogenous pacemakers internal or external?
Internal
Explain how the SCN interacts with light
Dark ⬇️ Information about light sent to SCN ⬇️ Transmitted to pineal gland ⬇️ Melatonin increases ⬇️ Induces sleep
Who spent 7 months in a underground cave?
Michael Siffre
What did Lobban say in reference to Luce and Segal’s research?
We used to hunt for over 24 hours in the summer, making use of the light. Now, social synchronisers such as eating behaviour and social customs has caused 24 hour cycles
What’s the main endogenous pacemaker?
SCN Of the hypothalamus
How did Michael Siffre’s research support the role of endogenous pacemakers?
Found that with the absence of exogenous zeitgebers his sleep cycle was still free running settling at just over 24 hours
What is a biological rhythm?
a pattern in physiological or psychological processes which repeats itself over a specified time period
What did Luce and Segal find?
People in the arctic circle sleep around 7 hours a day in the summer even though the sun doesn’t set
What is a circadian rhythm?
A rhythm that repeats once every 24 hours e.g sleep/wake cycle, body temperature
What’s an infradian rhythm?
Repeats less that once every 24 hours e.g menstrual cycle, SAD
What’s an ultradian rhythm?
Repeats more that once every 24 hours e.g. Stages of sleep, attention span
Other than the SCN, name another endogenous pacemaker
Hormones e.g melatonin
Other than light, name two more exogenous zeitgebers
Mealtimes Clocks Noise Temperature Social customs
Who studied a blind person?
Miles
What’s an IDA for the role of exogenous zeitgebers?
Deterministic
Can’t override exogenous zeitgebers and he environment
However, Born -
When told to wake up earlier than usual, participants were able to. This suggest that’s we have free will over our biological rhythms
How did Czeisler support Miles’s findings?
Used artificial dim light to alter circadian rhythms down to 22 hours and up to 28 hours
… Light is the main zeitgeber
What did Miles find?
The blind person had a circadian rhythm of 24.9 hours despite being exposed to other exogenous zeitgebers.
Supports the idea that light is the main zeitgeber
