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A2 Biopsychology AQA Psychology > Circadian Biological Rhythms > Flashcards

Circadian Biological Rhythms Flashcards

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1
Q

What is meant by a biological rhythm?

A

Change in body processes or behaviour in response to cyclical changes

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2
Q

What do biological rhythms involve?

A

Repetitions of certain physiological processes

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3
Q

When are they most often synchronised?

A

daily or monthly

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4
Q

What is determined by the length of time that a complete cycle takes until it begins again?

A

The type bodily rhythm it is classified as

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5
Q

Periodicity and example of a Circadian Rhythm?

A

Approx once a day i.e every 24 hours

sleepwake cycle

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6
Q

Periodicity and example of a Ultradian Rhythm?

A

More frequentely than once a day i.e shorter than 24 hours

Sleepcycle

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7
Q

Periodicity and example of a Infradian Rhythm?

A

Less frequentely than once a day i.e longer than 24 hours

Menstrual cycle

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8
Q

The circardian rhythm of the sleepwake cycle relies on both…?

A

Internal and external factors to control it.

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9
Q

What is meant by an Endogenous pacemaker?

A

Internal factors in the brain

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10
Q

What is meant by an Exogenic Zietgiber?

A

External factors in the environment.

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11
Q

What is the main endogenous pacemaker?

A

Suprachiasmatic Nucleus (SCN)

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12
Q

What and where is the SCN?

A

Small bundle of neurons located above the optic chiasm

Has an internal activity rhythm which persists even when isolated from the brain

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13
Q

How long will the SCN ‘free run’ in the absence of external cues?

A

Approx 25 hours instead of 24.

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14
Q

What is second endogenous pacemaker is known as and what is it responsible for?

A

Pineal gland, pes shaped gland

converting serotonin to melotonin

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15
Q

What happens when melotonin is released into circulation?

A

Acts on the brain’s sleep mechanisms

causing a reduction in alertness and drowsiness

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16
Q

Example of Exogenous Zeitgebers (external environmetal stimuli) that work with endogenous pacemakers?

A

Light and social cues i.e seasons, work etc.

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17
Q

The SCN is reset set every morning by what?

A

Light onset

18
Q

The visual receptors in the retina part of the eye recieve the light signal and activate what?

A

Retinohypothalamic tract pathway

19
Q

This pathway alerts the SCN and pineal gland affecting what?

A

melotonin production.

20
Q

Daylight inhibits the release of what?

A

melatonin

and darkness induces sleep

21
Q

When travelling across time zones, what happens to the (SNC) endogenous pacemakers and exogenic zeitgebers (destination time)?

A

They become unsynchronised

22
Q

What times these rhythms dictate and what happens to them?

A

Eating, sleeping, hormone regulations and body temperature.

They no longer correspond to the environment.

23
Q

Jet lag refers to?

A

The body not being able to immediately realign these rhythms.

24
Q

What does the SCN need to do in this new environment?

A

Entrain (resynchronise) which may take several days

25
Q

How does working at night disrupt Endogenous Pacemakers and Exogenous Zeitgebers working together?

A

SNC will be unsynchronised with available cues from exogenous zeitgebers such as daylight.

26
Q

What type of shifts causes the biggest disruption in circadian rhythms?

A

Backward rotating shifts

27
Q

What creates a risk of heart disease and cancer for shift workers?

A

hormone production (melotonin released during working hours)

lack of sleep (daytime sleep is more disrupted)

unhealthy eating (leads to irritability and decreases alertness)

28
Q

What are endogenous pacemakers responsible for?

A

regularity

29
Q

What are exogenous zeitgebers responsible for?

A

entrainment

30
Q

Practical applications of increasing productivity in shift workers include?

A

Follow forward rotating shifts

reduze ex and ep disruption by using bright lights during night shifts to mimick daylight.

31
Q

teenagers circadian rhythms are typically how much later than adults?

A

2 hours

Study by ox, 10am starts 19% exam improvment

32
Q

How does research into the control of the sleepwake cycle impace the econmy?

A

It has positive implications

33
Q

What does evidence from HUMAN studies do?

A

Support the role of INTERNAL endogenous pacemakers in the sleepwake cycle

34
Q

What did french speleogist Michel Siffre not have access to for 179 days un a subterranean cave?

A

Living in isolation he had no access to any exogenous Zeitgebers eg sound, calenders, or daylight

35
Q

Although erratic at first, his sleep cycle settled do to a regular..?

A

25-30 hour cycle.

36
Q

What is the sleep wake cycle largely controlled by?

A

Endogenous Pacemakers

37
Q

What is the sleep wake cycle entrained by?

A

exogenic zeitgebers

38
Q

What does evidence from ANIMAL studies support?

A

The role of INTERNAL endogenous pacemakers in the sleepwake cycles

39
Q

What was shown by mutant hamsters selectively bred to have a 20 hour sleepwake cycle? Ralph et al 1990

A

SNC cells from mutant hamsters transplanted to brains of hamsters with normal sleepwake cycle.
Normal Hamster’s Cycle began to alter and changed to the 20 hour of the donor mutant.

40
Q

What do these findings do to the validity of the function that endogenous pacemakers have in the sleepwake circadian rhythm?

A

Increases the validity of the key role of regularity

41
Q

Why is it difficult to make generalisations from supporting research?

A

One individual studied who was used to those conditions
can’t generalise = unrepresentative of everyone’s circadian rhythm

in animal research: extrapolation of findings = invalid explanation in human
exposed to different physicological structures, different ez’s affecting sleepwake cycles eg. clocks

42
Q

Why is it difficult to draw conclusions about the role of endogenous pacemakers?

A

same sample sizes in human studies

use of animal research

A2 Biopsychology AQA Psychology (14 decks)

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