Bio Flashcards
Circadian rhythm:strength
Practical application to shift work:shift work has been found to lead to a desynchronisation of circadian rhythms and can lead to adverse cognitive and physiological effects.For example research has shown that high shut workers suffer a concentration lapse at increasing the likelihood of accidents and shift workers are also three times mire likely to suffer heart disease as a results from the stress of adjusting to sleep and wake.This research has economic implication in terms of fainting worker productivity and preventing accidents within a work place.
Circadian rhythm:strength
By understanding circadian rhthind and their impact on health it can help determine the best time to administer drug treatments:for example the risk of a heart attack is greater in the early morning do drugs can be taken at night but not released until when they be most effective at dusk.This means that there are peak times to administer and dosage of a variety of drugs that can treat a range of disorders first example cancer and epilepsy.
Circadian rhythm:WEAKNESS
Lack of control:for example in the cave studies the exposed of artificial lights such as torches and phones was not controlled.It was assumed that it was only natural light that had an influence on our biological rhythms however there’s been research that’s found that dim artificial lighting could adjust our circadian rhythm between 22 to 28 hours.This means that the results of other lab studies may lack validity and it can also has practical value to when it comes to the use of electronic devices such as iPads in the day time.
Circadian rhythm:weakness
There is research support for example wever and aschoff had a group of participants live in a ww11 bunker for four weeks and found that the sleep wake cycle lasted just under 25 hours concluding that exogenous zeitgebers may have an impact on mediating the sleep wake cycle.This suggest that the body’s internal clock is 24 to 25 hours in the absence of external cues.
Infradian rhythm:weakness
Menstrual synchronisation is not always present in an all female sample:for example a researcher found there was no menstrual synchronisation in an all female participant sample.This suggest that there are other external/extraneous variables which may affect the timing and duration of their menstrual cycle.As mcclinkton did not control for such extraneous variables for example diet,smoking or alcohol consumption and this could have played a factor.This therefore could have occurred by chance additionally due to the small sample it may lack validity.
Infradian rhythm:weakness
It has an evolutionary value of the menstrual cycle:for example for our ancestors it may had been advantageous for all the females to estate together and for all the women to fall pregnant around the same time.This would mean that all the new horns would be cared for collectively within a social group increase the rates of offspring spring survival.However the validity of this evolutionary aspect would be questioned.As jeffery has argued that that if there were too many women cycling to their with in a social group this would produce completion for the hugest quality males and there by leering the first of any potential offspring.From this point of view the avoidance of synchrony would appear to be most adaptive and therefore naturally selected
Ultradian rhythm:strength
Research support for the stages of sleep:For example dement and kleitman studied 33 adults where their caffeine and alcohol intake had been controlled to remove the effects of extraneous variables and increase the validity of the finding.Using eegs scan they monitored the partials sleep patterns they found that rem active was highly correlated with the experiences of dreaming.Brain activity varied according to how vivid the dreams errr.Some participants were able to recall their dream when awaken during the rem sleep.This is the assumption that dream is associated with rem.Clear evidence supporting the distinctions of stages of sleep
Ultradian rhythm:counter
One limitation is that the study was carried out in a controlled lab setting:this is a Liston as they had monitors attached to measure there rhythms this may have been invasive for the participants leading them to sleep in a way that does not reflect their own ordinary sleep..This therefore makes investigating the sleep wake cycle difficult as this study lacks ecological validity.
Endogenous pacemaker on the sleep wake cycle:
Endogenous pacemakers are internal mechanism that govern biological rhyme in particular the circadian sleep wake cycle.
The suprachiasmatic nucleus is found on each side of the hemisphere in the brain this is the main endogenous pacemaker
It controls the other biotic rhythms and links to other areas of the brain like the pineal gland which is responsible for sleep and arousal
The scn also received information about light levels from the optic nerve which sets the circadian rhythm so that it is in synchronisation with the outside world for example day and light.
Exogenous zeitgebers:
These are external cues that may effect or entrain our biological rhythm for example the influence of light on our sleep wake cycle.
They can include social cues such as meal times and social activities
The most important is light for human it plays a role in the maintenance of the sleep wake cycle
Responsible for resetting the body main endogenous pacemaker the scn keeping it at a 24 hour cycle
Endogenous pacemakers:EVALUATION
There is research support for the ignorance of endogenous pacemakers in partial the scn in relation to the sleep cycle:For example Morgan bred hamsters so that they had a circadian rthyms of 20 hours rather than 24.Scn neurons from these abnormal hamsters were translated into the brains of normal hamsters who subsequently displayed the same abnormal circadian rhythm of 20 hours showing that t he transplanted scn had imposed its patterns onto the hamster.
However this research is difficult to generalised because of the use of hamster.Humans would respond very different to the manipulations of their biological rhythms not only because we are different biologically but also because of the vast differences between the environmental contexts.Therefore while this research signifies the importance of the scn and hoe endogenous pacemakers impact the biological rhythms research carried out on animals may be unable to explain the role of endogenous pacemakers on the sleep wake cycle of humans.
Exogenous zeitgebers:evaluation
There is research support for the role of this on the sleep wake cycle.For example when siffre returned from an underground stay with no clocks or light he believed that it was a month earlier than it was which demonstrates the importance of the endogenous zeitgeber (light) on the sleep wake cycle.
However suffers case study has been subject to critism as the research and the sole patient of this study there are issues with potential al research bias and lack of generalisability to the wider population.Therfore while this suggest that the 24 hour sleep wake cycle was increased due to the lack of exogenous zeitgebers showing the impact of such factors on the bodily rhyme.These findings need to be tested with caution.As it’s unable to tell if the exogenous zeitgebers effective sleeo wake cycle in a wider population
Exogenous and endogenous…
However deputed all the research supporting the role of the endogenous pacemaker and exogenously zeitgever the argument could still be consider reductionist for over simplifying a complex human phenomena.For example it could be argued that the sleep wake cycle is influenced by other people and social norm,sleep occurs when it is dark because that is the social norm and it wouldn’t by socially acceptable for a person to conduct their daily routines during the night.this suggest that the research discussed here could be critics for being too reductive about only considers a limited amount of factors and fails to consider other views.Therefore our understanding of the effect of them body on the sleep wake cycle is limited.
