BIOLOGICAL RHYTHMS A01 Flashcards
what are biological rhythms?
cyclical changes in the way that bilogical systems behave
what is one of the most important examples of bilogical rhythms in humans?
circadian rhythm
how long does the circadian cycle last?
24 hours
what is the cause of humans having these cyclical changes?
cause is evoloution and the environment
-because the environment has cyclical changes for 24 hours humans do too.
what do all organisms possess?
they all possess some kind of biological representation of a 24 cycle
what does having a circadian rhythm do to organisms?
optimises orgnaisms physiology(function) and behaviour to meet the demands of the 24 hour cycle.
what kind of demands does the circadian rhythm give?
when humans should
-eat
-sleep
-release hormones
what is the cicadian rhythm controlled by and where are they found?
body clocks in ALL cells
what are body clocks synchronised by and where is it found?
synchronised by scn β>found in the hypothalamus
what happens in the scn and why?
it is constantly resetβ> to keep in sync with the outside world
how is the snc constantly reset?
light provides primary input into the circadian system and light sets the body clock to the right time.
what is photoentrainment and what is an example?
it is when the circadiam rhythm becomes aligned with external factors eg. rhythm of light and dark
how does photoentrainment work?
the light sensitive cells in the eye act as detectorβ> send signals to the scn about environmetnal light levels
what happens with the information that is sent to the scn about enviormental light levels?
scn coordinates the activity of the entire circadian rhythm
light and darkness signals determine what?
when we sleep and wake up
what do cicadian rhythms also do?
dip and rise throught the day
when do the circadian rhythm dip?
1-3pm and 2-4am
what else is sleepiness determined by other than circadian rhythms
homestatic control
whta is homeostatic control
when homeostatus tells us the need of sleep increases because the amount of energy used while being awake
whta happens with the homestatic drive for sleep throughout the day?
increases the need for sleep
-dark
-used all energy
What are the internal body clocks called?
Endogenous pacemakers
What are the external factors called?
Exogenous zeitgebers
