Biological Rhythms

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  • Created by: FatCat3
  • Created on: 14-06-22 20:03
what are biological rhythms?
B.R are cyclical patterns within biological systems that have evolved in response to environmental influences.
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what are the 2 key factors that govern B.R?
-Endogenous pacemakers (internal)
-Exogenous Zeitgebers (external)
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what are the three rhythms?
Infradian (I= increase so more than 24 hours)
Circadian (C= 24 hours)
Ultradian (U= under 24 hours)
(ICU)
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what are circadian rhythms also known as and what do they do?
they are known as the body clock and they reset this body clock by using levels of light
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what is a key example of C.R?
what 2 factors can affect C.R from this example?
.sleep wake cycle
-light levels
-body temperature
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give the key info on how it works due to light levels?
the sleep wake cycle dictates when organisms should be asleep/awake, light is the primary input to this system (external). light is detected by the eye which sends a message concerning the level of light to the supra charismatic nucleus (SCN)-
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-SCN uses this info to coordinate the activity of the entire C.R. Homeostasis also helps in identifying when to sleep/be awake. ie when an individual is awake for a long time, homeostasis tells the body there is the need for sleep due to-
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-energy consumption, this homeostatic drive for sleep can in/decrease through day, reaching its max in the evening, when ppl fall asleep.
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how does the sleep wake cycle regulate from body temperature levels?
body temp is lowest in the early morning (36º at 4:30 am) and highest in the evenings (38º at 6pm), sleep occurs when core temp starts to drop, and body temp starts to rise towards the end of sleep, giving alertness in the morning.
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name the evaluations of C.R?
+R.S siffre stayed underground with no lights or clocks and he believed the date was a month earlier then it was as he thought 1 day was longer so he thought a few days had passed, showing the importance of external cues on the 24 hour cycle-
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-[-it's a case study so only 1 pp]
+individual differences, Duffy et al found morning ppl prefer to rise and go to bed early (6am and 10pm) whereas evening ppl prefer to wake up and. go bed. later (10 am and 1am), suggesting innate diffs-
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-[-does internal have an impact, idiographic approach]
-temp may be more important, Buhr et al found fluctuations in temp. he set timings of cells in the body and caused tissues and organs to become active-
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-/inactive. he claimed info about light levels is transformed into neural messages that set body temp. body temp fluctuates on a 24 hour C.R and even small changes can send a powerful signal to our body clocks, showing C.R are controlled by-
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-diff factors[+holistic approach may be needed]
+R.S Aschoff and Weber studied ppl living in a bunker without window and only artificial light they could turn off/on, they found PP went into longer sleep wake cycles of 25-27 hours showing natural light wa
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what are infradian rhythms?
these are another biological rhythm and they last longer than 24 hrs, influenced by internal and external factors.
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what is the key example of this rhythm and how does it work?
the female menstrual cycle, this is regulated by hormones that promote ovulation or or stimulate the uterus for fertilisation. ovulations happens halfway through the cycle when oestrogen is highest. after ovulation, progesterone levels-
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-increase for an embryo to be planted. the M.C can change ie usually is 28 days but can be 23 or 36.
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what is another example of an I.R and how does this happen?
Seasonal variation in mood/seasonal affective disorder (SAD), when some people become depressed in winter. Annual cycle, melatonin is secreted by the pineal gland during the night and is responsible, lack of light during winter causes-
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-long periods of melatonin recreation, linked to depressive symptoms
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name the evaluations of this
+R.S M.C governed by E.Z, Reinberg examined a woman who spent 3 months in a cave w only a small lamp to produce light, her M.C changed from 28 days to 25.7 days, showing lack of light effects M.Cs-
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-+ R.S Russell et al, found female M.C became synchronised w other females through odour exposure, study; woman had sweat samples of 1 group of women rubbed on their upper lip of other group, MC then were synchronised (tho groups were separated)-
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-suggesting M.C can be effected by pheromones which have an affect on ppl nearby rather then on the person producing them [+evolutionary psychologists say S of M.C is an evolutionary advantage as this means synchronised-
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-pregnancies leads to more women being able to give birth+ take care of children (of other women) at the same time]
+R.S, M.C are important regulators of behaviours, Penton Volk et al found women expressed a preference-
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-for feminised faces at the least fertile stage of M.C but a more masculine stage at the most fertile stage, indicating women sexual behaviours are monitored by I.R
+R.S melatonin. in SAD, Terman found rate of SAD is more-
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-common in Northern countries where nights are longer ie Terman found SAD affects nearly 10% of ppl living in New Hampshire (north USA) and only 2% of ppl in southern florida, so levels of melatonin plays a part [only correlation, no causation]
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what are ultradian rhythms, what is a key example and how does this process occur?
these last less then 24 hours and can be found in patterns of the human sleep cycle. ie alternations between REM and NREM sleep which has 5 stages. cycle starts at light sleep, progressing to deep sleep, then REM sleep. this cycle repeats every 90 mins-
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-EEG highlighted distinct brain wave patterns during sleep;
light sleep (stage 1+2), deep sleep(stage 3+4) and REM sleep (stage 5)
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what specifically happens at each stage?
state 1) 4-5%, light sleep, muscle activity slows down, occasional muscle twitching
stage 2) 45-55%, breathing patterns and heart rate slows down, slight decrease in body temp
stage 3) 4-6%, deep sleep begins, brain begins to generate slow delta waves-
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- stage 4) 12-55%, very deep sleep, rhythmic breathing, limited muscle activity, brain produces delta waves
stage 5) 20-25%, rapid eye movement, brainwaves speed up and dreaming occurs, muscles relax+ heart rate ↑, breathing is raised and shallow
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what is another U.R?
appetite/ meal patterns, most humans eat 3 times a day and appetite can ↑/↓ due to food consumption
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name the evaluations
-individual differences, diff sleeping patterns observed, tuker et al found diff in pp between each stage, specifically stage 3/4, demonstrating there is an innate individual diff in U.R [+study was in a controlled lab setting, -but situational factors sh
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-lacks ecological validity, research. investigates sleep patterns, PP must be subjected to a specific level of controls and be attached ti monitors that measure sleep rhythms, invasive for PP leading to false conclusions
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+flexibility of U.R, case study: Randy Gardener remained awake for 264 hours and experienced multiples issues like blurred vision, disorganised speech but he coped well with the sleep loss, after the study he slept for 15 hrs and recovered-
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-25% of his sleep, 70% of stage 4 and 50% of REM sleep and very little of other stages, for him to only need to sleep 15 hours to recover his sleep shows a high degree of flexibility in sleep cycle as others may need a lot longer to recover for the lost s
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what are B.R regulated by?
-endogenous pacemakers
-exogenous Zeitgebers
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how do endogenous pacemakers work?
E.P are internal mechanisms that govern biological rhythms, they can be altered and affected by EZ even if they are internal biological clocks. the most important EP is the supraciasmatic nucleus which is closely. linked to the pineal gland. the SCN-
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-, which lies in the hypothalamus, controls other. biological rhythms as it links to other areas of the brain responsible for sleep and arousal. SCN also receives info about light levels from the optic nerve which sets thee C.R so that it is in synch-
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-with the outside world. scan sends a signals to the pineal gland which leads to an ↑ in production of melatonin at night, helping to dice sleep as it makes a person feel tired.
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in simple words:
low levels of light →melanopsin carries signals to SCN → axon pathways to pineal gland → melatonin →induced sleep
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how do exogenous Zeitgebers work?
these external factors can reset biological organisms clock of an organism, can include social cues such as meal times and social activities but the most main one is light, which is. SCN contains receptors that are sensitive to light-
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-and this external cue is sued to synch body internal organs and gland. melanopsin is a pretties in the eye which is sensitive to light and carries signals to the SCN to set the 24 hour cycle. social cues can also let humans compensate for lack of natural
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name the evaluations
+R.S Morgan bred hamsters so they had C.R of 20 hrs, SCN neurons from these abnormal hamsters were transplanted into brains of normal hamsters which shared the same biological clock [-research carried on animals, humans more complex]
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+R.S, melanopsin, Shene and Arendt claimed that the majority of blind people who still have some light perception have normal C.R where as those w/o light perception had abnormal C.R
+R.S- Siffre- refer back to study prior
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-biologically reductionist viewpoint, ie behaviourist approach would suggest that bodily rhythms are influenced by social norms and ppl because sleep occurs at night as the night would be an abnormals time to get daily activities done-
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-as its dark/ theres no light, so only having a single biological mechanism to explain everything fails to consider other viewpoints
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Other cards in this set

Card 2

Front

what are the 2 key factors that govern B.R?

Back

-Endogenous pacemakers (internal)
-Exogenous Zeitgebers (external)

Card 3

Front

what are the three rhythms?

Back

Preview of the front of card 3

Card 4

Front

what are circadian rhythms also known as and what do they do?

Back

Preview of the front of card 4

Card 5

Front

what is a key example of C.R?
what 2 factors can affect C.R from this example?

Back

Preview of the front of card 5
View more cards

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