Biopsychology Flashcards

Question

Label the motor neuron diagram

Answer 1

- electrical impulses being sent to release NTs

Answer 2

- neurons transmit electrical impulses (action potentials) between presynaptic neuron and postsynaptic neuron - when action potential reaches presynaptic terminal, it triggers release of NTs from sacs on the presynaptic membrane (vesicles) => process called exocytosis - released NTs diffuse across synaptic cleft where it binds to specialised postsynaptic receptor sites

Answer 3

- synaptic transmission takes only a fraction of a second - effects can be terminated by re-uptake - NTs are taken back by vesicles on presynaptic neuron - stored for later release - the quicker the NT is taken back, the shorter the effects

Answer 4

- can be excitatory or inhibitory => most can be both but GABA is purely inhib - excit NTs cause electrical charge in membrane of postsynaptic neuron => results in excit postsynaptic potential (EPSP) => post synaptic neuron more likely to fire impulse - inhib NTs cause inhib postsynaptic potential (IPSP) => postsynaptic neuron less likely to fire impulse

Answer 5

- neuron can receive both EPSPs and IPSPs at same time - likelihood of neuron firing an impulse is determined by adding excit and inhib synaptic input - net result of calculation (summation) determines whether or not the neuron will fire an impulse - if net effect is inhib, neuron will not fire - if net effect is excit, neuron will fire

Answer 6

- information can only travel in one direction at a synapse - vesicles containing NTs are only present on presynaptic membrane - receptors for NTs are only present on postsynaptic membrane - it is the binding of NTs to the receptors which enables information to be transmitted - diffusion means they can only go from high to low concentration

Answer 7

- psychoactive drugs affect transmission of NTs - pain meds mimic effects of inhib NTs - stimulation of postsynaptic receptors by inhib NT lead to inhibition of postsynaptic membrane - inhib NT binding to postsynaptic receptors makes postsynaptic neuron less likely to fire - due to summation, if inhib NTs are higher than excit they can inhibit action potential from occuring - therefore pain meds would decrease overall activity and reducing brain activity may lead to less pain

Answer 8

- provides a chemical system of communication in body via blood stream - works alongside nervous system to control vital functions in the body - acts more slowly than nervous system but has very widespread effects - uses endocrine glands

Answer 9

- produce and secrete hormones into bloodstream which are required to regulate bodily functions - each gland produces different hormones which regulate activity of organs/tissues in the body - although hormones come into contact with most cells, they only affect certain cells => target cells - target cells respond to particular hormone as they have receptors for it - when enough receptor sites stimulated by hormone, there is a physiological reaction

Answer 10

- located in brain - produces hormones whose function is to influence release of other hormones from other glands - controlled by hypothalamus - split into two divisions

Answer 11

- receives information about basic functions of body - sends signal to pituitary gland in form of releasing hormone - causes pituitary gland to send stimulating hormone into bloodstream to tell target gland to release its hormone - as levels of this hormone rise in bloodstream, the hypothalamus shuts down production of releasing hormone and pituitary gland shuts down secretion of stimulating hormone

Answer 12

- anterior pituitary gland => releases hormone ACTH which regulates levels of hormone cortisol - posterior pituitary gland => responsible for releasing hormone oxytocin which is crucial for infant/mother bonding

Answer 13

- two adrenal glands situated on top of kidney - each gland is made up of two parts

Answer 14

- adrenal cortex - adrenal medulla

Answer 15

- outer section of adrenal gland - produces cortisol => produced in high amounts when someone is experiencing chronic stress - cortisol also responsible for cardiovascular system, e.g. will increase blood pressure and cause blood vessels to constrict

Answer 16

- inner section of adrenal gland - produces adrenaline => hormone needed for fight or flight response that is activated when someone is acutely stressed - increases heart rate, dilates pupils and stops digestion

Answer 17

- pituitary gland - hypothalamus - pineal gland - thyroid and parathyroid gland - thymus - pancrease - ovary - adrenal glands - placenta - testicle

Answer 18

- used in fight or flight response - involves sympathetic nervous system, adrenaline and parasympathetic nervous system

Answer 19

- when person is faced with threat, amygdala is activated - amygdala associates sensory signals with emotions associated to fight or flight - amygdala then sends distress signal to hypothalamus => command centre in brain which communicates with rest of body through sympathetic nervous system - different response for acute and chronic stressors

Answer 20

- when threat has passed, parasympathetic nervous system dampens stress response - slows heartbeat and reduces blood pressure

Answer 21

- when SNS is triggered, it begins process of preparing body for rapid action necessary for fight or flight - sends signal to adrenal medulla to release hormone adrenaline

Answer 22

- makes heart beat faster, pushing blood to muscles, heart and other vital organs, and blood pressure increases - breathing becomes faster so more oxygen can be taken in - blood sugar released as well as fats, which flood bloodstreams, supplying energy to parts of body associated with fight or flight response

Answer 23

- if brain continues to perceive something threatening, second system kicks in - as the initial surge of adrenaline subsides, the hypothalamus activates a stress response system called the HPA Axis - H => hypothalamus, P => pituitary gland, A => adrenal glands

Answer 24

- HPA relies on series of hormonal signals to keep SNS working - in response to continued threat, hypothalamus releases chemical messenger CRH - released into bloodstream in response to stressor

Answer 25

- on arrival at pituitary gland, CRH causes pituitary to produce and release ACTH - ACTH is transported in bloodstream to target sites in adrenal glands

Answer 26

- ACTH stimulates adrenal cortex to release various stress related hormones => cortisol - cortisol is responsible for several effects in body that are important for fight or flight

Answer 27

- HPA axis system is efficient at regulating itself - both hypothalamus and pituitary gland have special receptors that monitor cortisol levels - if these rise above normal, they initiate reduction in CRH and ACTH levels => brings cortisol back to normal

Answer 28

- makes sense from evolutionary psychology point of view as it would have helped individual to survive by fighting or fleeing a threat - studies supports claim that adrenaline is essential in preparing body for stress, people who have malfunctioning adrenal glands do not have a normal fight or flight response to stress

Answer 29

- Gray (1988) - Taylor (2000) - Von Dawans (2012)

Answer 30

- states first reaction to stress is freeze - involves person stopping, looking and listening and being hyper vigilant to danger

Answer 31

- found females tend and befriend in times of stress - tend and befriend refers to protection of offspring and seeking out social groups for mutual defence - women have hormone oxytocin which means they are more likely to stay and protect offspring

Answer 32

- found even males tend and befriend - e.g. 9/11 terror attacks, both males and females showed tend and befriend as they tried to contact loved ones and help each other

Answer 33

- principle that functions have specific locations within the brain - research shows some functions are more localised than others - e.g. motor and somatosensory functions are highly localised to particular areas of cortex - other functions are more widely distributed - e.g. language system uses several parts of the brain

Answer 34

- visual centre - auditory centre - motor area - somatosensory area - language centre

Answer 35

- visual cortex processes information such as colour and shape - located in occipital lobe of both hemispheres - visual processing starts in retina where light enters and strikes photoreceptors - nerve impulses from retina are transmitted to brain via optic nerve - majority terminate in thalamus (relay station) passing information onto visual cortex

Answer 36

- auditory cortex processes information such as pitch and volume - lies within temporal lobe in both hemispheres - auditory pathway begins in cochlea in inner ear => sounds waves converted to nerve impulses - impulses travel via auditory nerve to auditory cortex - basic decoding occurs in brain stem, thalamus carries out further processing before impulses reach auditory cortex

Answer 37

- responsible for voluntary movements - located in frontal lobe of both hemispheres - different parts of motor cortex control different parts of body - these areas are arranged logically next to one another - damage to this area can cause loss of muscle function/paralysis in one/both sides of body => dependent on which hemisphere has been affected

Answer 38

- responsible for processing sensations such as pain and pressure - located in parietal lobe of both hemispheres

Answer 39

- Broca’s Area - Wernicke’s Area

Answer 40

- named after Paul Broca => treated patients who had difficult producing speech - found they had lesions to left hemisphere of frontal lobe - damage to Broca’s area causes expressive aphasia - disorder affects language production but not understanding - speech lacks fluency and patients have difficulty with certain words which help sentences function

Answer 41

- in left hemisphere of temporal lobe - Carl Wernicke found patients with lesion to this could speak but were unable to understand language - concluded this area is responsible for processing of spoken language - connected to Broca’s area by neural loop - damage causes receptive aphasia => impaired ability to understand language

Answer 42

- forebrain - midbrain - hindbrain

Answer 43

- brain scans - neurosurgical evidence - Phineas Gage - aphasia studies

Answer 44

- lot of evidence suggests neurological functions are localised - Peterson et al. (1988) used brain scans to show how Wernicke’s area was active during listening task and Broca’s area active during reading task - suggests language is localised to these areas - brain scans increase validity

Answer 45

- neurosurgery requires specific areas of brain to be deliberately damaged to help patients with mental illness - Doughtery et al. (2002) reported on 44 OCD patients who undergone brain surgery => required lesioning certain area of brain responsible for OCD - after 32 weeks, found 1/3 recovered from symptoms whilst 14% had some recovery

Answer 46

- suffered traumatic accident on railway tracks - suffered brain damage with pole forcing temporal lobe out of brain - Gage suffered a completed charge of personality after accident suggests personality may be localised to temporal lobe

Answer 47

- aphasia means inability to produce or understand speech - studies have shown people who suffer damage to Broca’s area suffer expressive aphasia - studies also show people who suffer damage to Wernicke’s area suffer receptive aphasia

Answer 48

- Dronkers et al. (2007) - Dejerine (1892) - Bavelier et al. (1997)

Answer 49

- re-examined preserved brains of two of Broca’s patients - MRI scans revealed several areas of brain had been damaged - lesions to Broca’s area cause temporary speech disruption, they do not usually result in severe disruption of language - language is a more widely distributed skill than originally thought

Answer 50

- it may be that how brain areas communicate with each other is more important than specific brain regions - Dejerine reported patient who could not read because of damage between visual cortex and Wernicke’s area

Answer 51

- found there are individual differences in which brain areas are responsible for certain functions - found that different brain areas are activated when a person is engaged in silent reading - observed activity in the right temporal lobe, left frontal lobe and occipital lobe - means function of silent reading does not have a specific location within the brain

Answer 52

- refers to notion that certain functions are principally governed by one side of the brain

Answer 53

- language centres - Broca’s area thought to be responsible for production of speech => now thought to involve a wider network - damage to Broca’s area leads to expressive aphasia - Wernicke’s area considered to play a vital role in understanding language - damage to Wernicke’s area leads to receptive aphasia

Answer 54

- dominant for visuo-spatial functions

Answer 55

- by a bundle of nerve fibres => corpus callosum - enables information to be communicated between the two hemispheres - many researchers suggest two hemispheres work together to form most tasks as part of a highly integrated system

Answer 56

- Rogers et al. (2004) - Tonnessen et al. (1993)

Answer 57

- makes sense from evolutionary perspective - increases neural processing capacity => adaptive - by using one hemisphere to engage in a particular task, it leaves other hemisphere free to engage in another function - Rogers found hemispheric lateralisation in chickens is associated with an ability to perform two simultaneous tasks => finding food and being vigilant

Answer 58

- lateralisation means we can study left handedness and why they may be prone to allergies and illnesses - people who are left handed tend to suffer higher rates of allergies and problems with immune system - Tonnessen found small but significant relationship between handedness and immune disorders => suggests link between lateralisation and development of immune system

Answer 59

- Szaflarksi et al. (2006) - Turk et al. (2002) - Danelli et al. (2013)

Answer 60

- lateralisation changes with age and is therefore not set in stone - Szaflarski found language became more lateralised to left hemisphere put to age 25 but decreased after - suggests we should be cautious in assuming brain lateralisation is set in stone throughout life as research has suggested lateralisation is only relevant up to a certain age

Answer 61

- JW (split brain patient) developed capacity to speak using right hemisphere, with the result that they could speak about information in either left visual field or right usual field hemisphere => more fluent in left - would appear language is not lateralised entirely to left hemisphere

Answer 62

- if one hemisphere is damaged, undamaged regions on opposite hemisphere can compensate - Danelli reported case of EB, who had his left hemisphere removed due to tumour - language appeared almost normal in everyday life in terms of vocabulary and grammar - however, systematic testing revealed subtle grammatical problems as well as poorer normal scores on picture naming and reading of loan words - language function can be largely preserved but right hemisphere cannot provide perfect mastery

Answer 63

- surgeons cut corpus callosum in order to prevent violent electrical activity caused by epileptic seizures crossing from one hemisphere to the other - patients who underwent this form of surgery are referred to as split brain patients

Answer 64

- Sperry and Gazzaniga (1968) - information from left visual field goes into right hemisphere - information from right visual field goes into left hemisphere - because in split brain patients, the corpus callosum has been severed, there is no way for information presented to one hemisphere to travel to other

Answer 65

- asked to stare at dot in centre, information presented in either LVF or RVF - then asked to make responses with either left hand (right hemisphere), right hand (left hemisphere) or verbally (left hemisphere) without being able to see what their hands were doing - may be flashed image of dog in RVF then asked what they saw - they will answer dog as information went to left hemisphere where language centres are - if picture of cat shown in LVF and they asked to say what they saw, they will not as information went to right hemisphere but they will draw picture of cat with left hand

Answer 66

- enabled discovery of hemispheric lateralisation - experiments on split brain patients are highly controlled and scientific

Answer 67

- patients often had drug therapy for epilepsy much longer than others which could affect how brain works, means findings cannot be generalised - many studies have as few as three participants making generalisation difficult - data is articulatory, in real world severed corpus callosum can be compensated by unrestricted use of both visual fields => lacks ecological validity

Answer 68

- brain’s ability to change and adapt as a result of experience - plasticity allows brain to cope better with indirect effects of brain damage

Answer 69

- life experiences - video games - meditation

Answer 70

- nerve pathways that are used frequently develop strong connections => those rarely used die - by developing new connections and reducing weak ones, the brain is able to adapt to a change in environment - however, there is also a decline in cognitive functioning with age attributed to these changes - Boyke et al. (2008) taught 60 year olds a new skill (juggling), this increased grey matter in visual cortex

Answer 71

- Kuhn et al. (2014) compared control group to a group who had been given video game training for at least 30 minutes a day for 2 months on super Mario - found that playing video games caused significant increase in grey matter in visual cortex, hippocampus, and cerebellum - playing video games results in new synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory and motor performance

Answer 72

- Davidson et al. (2004) compared eight monk practitioner of Tibetan meditation with ten students with no meditation experience - EEG picked up greater gamma wave activity in monks, even before they started meditating - gamma waves coordinate neural activity

Answer 73

- Kempermann et al. (1998) - Maguire et al. (2000)

Answer 74

- found increased number of new neurons for rats housed in complex environments compared to those housed in basic cages - increase in neurons was most prominent in hippocampus => involved in forming of new long term memories and ability to navigate

Answer 75

- measured grey matter in brains of London taxi drivers using MRI scan - hippocampus in taxi drivers was significantly larger than a control group - positively correlated with amount of time they spent as a taxi driver

Answer 76

- form of plastiicty - following damage caused by trauma, brain can redistribute/transfer functions performed by damaged areas to undamaged areas - when brain is still maturing, recovery from trauma is more likely (Ebert et al., (2001) - however brain is capable of plasticity and functional recovery at any age - studies suggested women recover from brain injury quicker than men

Answer 77

- axon sprouting => growth of new nerve endings which connect with other undamaged nerve cells to form new neural pathways - denervation supersensitivity => axons that do similar task become aroused to a higher level to compensate for ones that are lost, however can have negative consequence of over sensitivity to messages - recruitment of homologous area => from opposite side of brain to perform specific task

Answer 78

- transfer of functions from damaged areas of brain to undamaged areas => neural reorganisation - growth of new neurons and/or connections to compensate for damaged areas => neural regeneration

Answer 79

- spontaneous recovery from brain injury tends to slow down after a number of weeks - physiotherapy may be required to maintain improvements in functioning - techniques can include movement therapy and electrical stimulation of brain to counter deficits in motor and cognitive functioning

Answer 80

- phantom limb syndrome - Hubel and Torten Wisel (1963)

Answer 81

- can be used as evidence of neural reorganising - is the continued experience of sensation in a missing limb, as if it was still there - sensations are often unpleasant and painful - is thought to be caused by neural reorganisation in the somatosensory cortex that occurs as a result of limb loss - Ramachandran and Hirstein (1998)

Answer 82

- functional magnetic resonance imaging (fMRI) - post mortem examination - electroencephalogram (EEG) - event related potentials (ERPs)

Answer 83

- psychologists are able to look for abnormalities in the brain that explain behaviour when patient is dead - post mortem studies have found a link between brain abnormalities and psychiatric disorders - eg. There is evidence of reduced glial cells in frontal lobe of patients with depression

Answer 84

- provide indirect measure of neural activity - uses magnetic fields and radio waves to monitor blood flow in brain - measures change in energy released by haemoglobin, reflecting activity of brain to give moving picture of brain - activity in regions of interest can be compared during a base link task and a specific activity

Answer 85

- directly measures general neural activity in brain, usually linked to states such as sleep and arousal - electrodes placed on scalp and deflect neural activity below position - different numbers of electrodes can be used depending on focus of research - when electrical signals from different electrodes are graphed over a period of time, the resulting representation is called an EEG pattern - EEG patterns of patients with epilepsy show spikes of electrical activity

Answer 86

- electrodes placed on scalp and directly measure neural activity in response to a specific stimulus introduced by researcher - difficult to pick out from other electrical activity being generated in brain - to establish response to a target stimulus, requires many presentations of this stimulus and responses are averaged - any extraneous neural activity that is not related will not occur consistently whereas activity linked to stimulus will

Answer 87

- strength; allow for more details examinations of anatomical and neurochemical aspects of brain than would be possible with other methods, they have enabled researchers to examine deeper regions such as hippocampus and hypothalamus - weakness; lack validity as people die in variety of circumstances and at varying stages of diseases, similarly lengthy of time between death and post mortem can affect brain - weakness; small sample meaning sample cannot be representative of target population so problematic to generalise

Answer 88

- strength; captures dynamic brain activity as opposed to post mortem which purely shows physiology of brain - strength; good spatial resolution - weakness; interpretation is complex and affect by poor temporal resolution - weakness; expensive leading to reduced sample reducing validity

Answer 89

- strength; used in clinical diagnosis - weakness; cheaper than fMRI so more widely used - weakness; poor spatial resolution

Answer 90

- strength; can measure processing of stimulus even in absence of behaviour response, therefore possible to measure covertly the processing of a stimulus - strength; cheaper than fMRI so more widely used - strength; good temporal resolution - weakness; poor spatial resolution - weakness; only sufficiently strong voltage changes generated across scalp are recordable, important electrical activity occurring deeper in brain is not recorded, tend to be restricted to neocortex

Answer 91

- cyclical changes in the physiological systems - evolved because the environment in which organisms live have cyclical changes - three types

Answer 92

- circadian rhythms - ultradian rhythms - infradian rhythms

Answer 93

- any cycle that lasts for 24 hours - nearly all organisms possess a biological representation of the 24 hour day - these optimise an organism’s physiological behaviour to best meet varying demands of day/night cycle

Answer 94

- driven by suprachiasmatic nuclei (SCN) in hypothalamus - this pacemaker must constantly be reset so our bodies are in synchrony with outside world - natural light provides input, setting SCN to correct time in a process called photoentrainment - SCN then uses this information to coordinate activity of circadian rhythms throughout the body

Answer 95

- sleep wake cycle - core body temperature - hormone production

Answer 96

- light and darkness are external signals determine when we feel need to sleep/wake up - rhythms dumps and rises at different times, strongest drive is between 2-4am and 1-3pm - release of melatonin from pineal gland is at peak during dark hours => induces sleep by inhibiting neural mechanisms that promote wakefulness, light suppresses production of melatonin - sleep is also under homeostatic control => when awake for long time, homeostasis tells us need for sleep is increasing

Answer 97

- practical applications => chronotherapeutics - time patient takes medication is important for treatment success - it is essential that right concentration of drug is released in target area of body at time drug is most needed - e.g. risk of heart attack is greatest during early morning hours - medications developed that are taken before going to sleep but not released until early morning hours

Answer 98

- Cziesler et al. (1999) - individual differences - Arctic studies

Answer 99

- research on circadian rhythms has not isolated people from artificial light - previously believed only natural light affected rhythm - however more recent research suggests this may not be true - Cziesler altered participant’s circadian rhythms down to 22 hours and up to 28 hours by using artificial light

Answer 100

- Cziesler et al. (1999) found cycles can vary from 13 hours to 165 hours - another individual difference is when the rhythm reaches its peak. Morning people prefer to rise early and go to bed early whereas evening people prefer to rise late

Answer 101

- studies of individuals who live in Artic regions, where sun does not set in Sumer months, show normal sleeping patterns despite prolonged exposure ot light - suggests there are occasions where exogenous zeitgeber of light may have little bearing on internal biological rhythm

Answer 102

- span a period less than 24 hours - e.g. five sleep stages - human sleep follows a pattern alternating between rapid eye movement (REM, 5 stages) and non rapid eye movement (NREM, 4 stages) - cycle repeats itself every 90 minutes

Answer 103

- each stage shows distinct EEG pattern - as person enters deep sleep, brainwaves slow and breathing and heart rate decrease - during fifth stage, EEF pattern resembles that of an awake person => dreaming

Answer 104

- referred to 90 minute cycle as basic rest activity cycle (BRAC) - suggested this 90 minute cycle continues when awake - during day, rather than moving through sleep stages, we move from a state of alertness to physiological fatigue - studies suggest human mind can focus for about 90 minutes - towards end of 90 mins, body begins to run out of resources, resulting in loss of concentration, fatigue and hunger

Answer 105

- Ericsson et al. (2006) found support - studied group of elite violinists - found among this group, practise sessions were limited to 90 minutes at a time - they frequently napped to recover from practise, with best violinists napping more - same pattern found among athletes, chess players and writers - fits with BRAC

Answer 106

- Tucker et al. (2007) - suggests there are individual differences in ultradian rhythm - biologically determined and may even be genetic in origin - participants studied over 11 consecutive days and nights in lab environment - researchers assessed sleep duration, time taken to fall asleep and amount of time in each stage - differences found in all characteristics

Answer 107

- span period of longer than 24 hours - e.g. menstrual cycle which lasts for a month - considerable variations in the length of this cycle

Answer 108

- hormones regulate menstrual cycle - ovulation occurs roughly halfway through menstrual cycle, when oestrogen levels are at peak, and usually last for 16-32 hours - after ovulation, progesterone levels increase in preparation for possible implantation of an embryo in the uterus

Answer 109

- can affect behaviour - Penton-Voak (1999( found women express preference for feminised male faces when choosing a partner for a long term relationship - however showed preferences for masculinised faces during ovulation

Answer 110

- menstrual cycle is not only governed by infradian rhythm - when several women of childbearing age live together and do not take oral contraceptives, their menstrual cycles synchronise - in one study, samples of swear were collected from one group of women and rubbed onto upper lip of another group - menstrual cycles than became synchronised - suggests synchronisation is affected by pheromones => chemical substances produced and released into environment by animal which affects behaviour of others of same species

Answer 111

- internal biological rhythms must be tuned in order to stay in keeping with the outside world - in order to achieve this, we have endogenous pacemakers and exogenous zeitgebers which reset out biological rhythms everyday

Answer 112

- internal biological rhythms - most important pacemaker is suprachiasmatic nuclei (SCN) - tiny cluster of nerve cells in hypothalamus - SCN plays important role in generating circadian rhythms - acts as master clock, linking other brain regions and controlling all biological clocks throughout the body

Answer 113

- neurons within SCN synchronise with each other, so target neurons in sites elsewhere in body receive time coordinated signals - these peripheral clocks can maintain circadian rhythm, but not for long, which is why they are controlled by SCN - possible due to SCN’s built in circadian rhythm, which only needs resetting when external light levels change - SCN receives information about light levels though optic nerve - if biological clock is running slow then morning light shifts clock

Answer 114

- regulates manufacture and secretion of melatonin in pineal gland via interconnecting neural pathway - SCN sends signal to pineal gland, directing to increase production and secretion of melatonin at night and decrease as light levels increase - melatonin induces sleep by inhibiting brain mechanisms that promote wakefulness

Answer 115

- Folkard (1996) - studies a university student who spent 25 days in a lab - had no access to exogenous zeitgeber of light to reset SCN - however, at the end of her 25 days, her core temperature rhythm was still at 24 hours - indicates we do not need exogenous zeitgeber of light to maintain internal biological rhythms

Answer 116

- student studied by Folkard (1966) sleep wake cycle extended to 30 hours - periods of sleep showed as long as 16 hours - suggests we do need exogenous zeitgeber of light to maintain our internal biological rhythms

Answer 117

- environmental events that are responsible for maintaining biological clock of organism - most important zeitgeber for most animals is light

Answer 118

- receptors in SCN are sensitive to changes in light levels during day - use this information to synchronise activity of body’s organs and glands - light rests internal biological clock each day, keeping it on a 24 hour cycle - protein in retina (melanopsin) which is sensitive to light is critical to this system

Answer 119

- when people move to night shift or travel to different country with different time zone, their endogenous pacemakers try impose their inbuilt rhythm of sleep - this however is not out of synchrony with exogenous zeitgeber of light - out of sync biological rhythms lead to disrupted sleep patterns, increased anxiety and decreased alertness and vigilance

Answer 120

- majority of blind people who still have light perception have normal circadian rhythms. Blind people without light perception show abnormal circadian rhythms. Shows vital role the exogenous zeitgeber of light levels play in maintaining internal biological rhythms - Burgess et al. (2003) found exposure to bright light prior to an east-west flight decreases time needed to adjust circadian rhythms to local time

Answer 121

- studies of individuals who live in Artic regions, where sun does not set in summer months, show normal sleeping patterns despite prolonged exposure to light - suggests there are occasions where exogenous zeitgeber of light may have very little bearing on internal biological rhythms