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AQA A-Level Psychology > 06 Biopsychology > Flashcards

06 Biopsychology Flashcards

1
Q

What is the central nervous system, its role and how it achieves this role?

A
  • The central nervous system consists of the brain and spinal cord
  • Its role is to regulate the body’s physiological processes and to control behaviour
  • The brain recieves information from the sensory receptors and provides a response through the muscles and glands
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2
Q

What are the four main parts of the brain and their role?

A
  1. Cerebrum: the largest part of the brain and it consists of 4 lobes and is split in the middle into the right and left hemispheres
  2. Cerebellum: responsible for motor skills, balance and coordinating muscles for precise movements
  3. Diencephalon: contains the thalamus (controls consciousness, alertness and sleep) and the hypothalamus (regulate body temperature, stress response, hunger and thirst)
  4. Brain stem: regulates breathing and heart rate
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3
Q

What are the roles and characteristics of the spinal cord?

A
  • The main function of the spinal cord is to relay information between the brain and the rest of the body
  • Allows brain to regulate physiological processes like digestion and breathing and coordinate voluntary movements
  • The spinal cord in connected to various parts of the body through pairs of spinal nerves which connect to specific muscles and glands
  • If the spinal cord is damaged, any body parts connected below the damage would be cut off and stop functioning - paralysis
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4
Q

Describe the peripheral nervous system.

A

The peripheral nervous system consists of the nervous system except from the central nervous system (brain and spinal cord)
Responsible for transmitting messages from the body to the CNS via neurons
Split into two divisions: somatic and autonomic

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5
Q

Outline the two divisions of the peripheral nervous system.

A

Somatic nervous system:
- controls voluntary movement under conscious control
- connects the sense with the CNS
- has both sensory pathways and motor pathways
- controls skeletal muscles
- is controlled by the motor cortex in the brain

Autonomic nervous system
- controls involuntary behaviour and processes
- only has motor pathways
- controls smooth muscles, glands and internal organs
- controlled by the brain stem

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6
Q

Describe the two divisions of the autonomic nervous system

A

Sympathetic nervous system: activated when a person is stressed:
- Heart rate and breathing increases
- Digestion is halted
- Pupils dilate
- Blood flow increases and is diverted away from the skin and towards the muscles
- Salivation reduces
Parasympathetic nervous system: activated when the body is relaxing and conserving energy
- Heart rate and breathing slows down
- Digestion starts again
- Pupils constrict
- Salivation increases

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7
Q

Define the neuron.

A

The neuron is a specialised cell designed to carry electrical impulses to and from the CNS

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8
Q

What are the different parts of the neuron?

A
  • Cell body: control centre of the neuron
  • Nucleus: contains genetic material
  • Axon: a long fibre that carries impulses from the cell body to the axon terminal
  • Axon Terminal: contains vesicles which release neurotransmitters
  • Dendrites: recieves electrical impulse/action potential from the previous neuron or sensory recepetors
  • Myelin sheath: an insulating layer on the axon which protects it and increases speed of transmission
  • Schwann cells: makes up the myelin sheath
  • Nodes of Ranvier: gaps in the myelin sheath that speed up transmission of electrical impulses
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9
Q

Briefly outline the difference between the diagrams of motor neurons and sensory neurons.

A

Sensory neurons have the cell body and nucleus in the middle but in the motor neuron the cell body and nucleus are on one side

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10
Q

Describe the characteristics and roles of the sensory neuron.

A
  • Found in the sensory receptor
  • Carry electrical impulses from the receptors to the CNS via the PNS
  • Converts sensory information into electrical impulses
  • Electrical impulses are converted in the brain into sensations
  • Sometimes sensory neurons terminate at the spinal cord when a quick response is needed - a reflex arc
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11
Q

Describe the traits of motor neurons.

A
  • Motor neurons lie in the CNS but project their axons out
  • They send electrical signals from the CNS to the effectors e.g. glands and muscles
  • When a motor neuron is stimulated, it releases neurotransmitters which bind to the receptors on the muscle which triggers a response leading to movement
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12
Q

Describe the function and role of relay neurons.

A
  • Relay neurons lie in the central nervous system
  • Connect sensory and motor neurons so they can communicate
  • In the reflex arc, the relay neurons in the spinal cord process the sensation and decide how to respond without waiting for the brain to receive the impulses and process the pain
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13
Q

Outline the steps of synaptic transmission.

A
  1. Action potential reaches end of pre-synaptic axon terminal
  2. Triggers release of neurotransmitters from the vesicles on the pre-synaptic membrane in a process called exocytosis
  3. Neurotransmitter diffuses across synaptic cleft
  4. Binds to specialised post-synaptic receptor sites
  5. Neurotransmitters are taken back by the vesicles on the pre-synaptic membrane where they are stored for later release.
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14
Q

Explain excitatory and inhibitory neurotransmitters.

A
  • Excitatory neurotransmitters causes an electrical charge in the membrane of the post-synaptic neuron
  • resulting in an excitatory post-synaptic potential (EPSP), meaning that the post-synaptic neuron is more likely to fire an impulse
  • Inhibitory neurotransmitters cause an inhibitory postsynaptic potential (IPSP), making it less likely that the neuron will fire an impulse.
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15
Q

How does a neuron decide whether to fire or not?

A
  • The likelihood that the neuron will fire an impulse is determined by adding up the excitatory
    and the inhibitory synaptic input.
  • The net result of this calculation, known as summation, determines whether or not the neuron will fire an impulse.
  • Net effect is inhibitory = no fire; excitatory = fire
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16
Q

Why can impulses only travel in one direction?

A
  • Vesicles only lie on the pre-synaptic membrane
  • Receptors are only present on post-synaptic membrane
  • Diffusion can only occur from high concentration to low concentration so neurotransmitters can only travel from pre-synaptic membrane to post-synaptic membrane
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17
Q

How do pain medications work in terms of excitatory and inhibitory neurotransmitters?

A
  • Medications work by increasing or decreasing levels of neurotransmitters
  • Pain medications increase levels of inhibitory neurotransmitters
  • If a post-synaptic membrane is stimulated by an inhibitory neurotransmitter, the net effect after summation will be inhibitory
  • The post-synaptic neuron is less likely to fire and inhibits action potential
  • Therefore they reduce overall activity and reduce brain activity thus feeling less pain
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18
Q

Outline the endocrine system.

A
  • The endocrine system provides a chemical system of communication in the body via the blood stream.
  • Endocrine glands produce and secrete hormones into the bloodstream which are required to regulate many bodily functions.
  • Target cells respond to a particular hormone because they have specific receptors for that hormone.
  • When enough receptor sites are stimulated by that hormone there is a physiological
    reaction.
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19
Q

Describe the pituitary gland.

A
  • Pituitary gland is located in the brain
  • Excretes hormones whose primary function is to influence the production of other hormones
  • Controlled by the hypothalamus (deals with regulation of body temperature, stress response, hunger and thirst)
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20
Q

How do pituitary gland and hypothalamus work together to regulate basic functions and processes of the body?

A
  1. The hypothalamus receives information from many sources about the basic functions of the body.
  2. The hypothalamus then sends a signal to the pituitary gland in the form of a releasing hormone
  3. This causes the pituitary gland to send a stimulating hormone into the bloodstream to tell the target gland to release its hormone.
  4. As levels of this hormone rise in the bloodstream the hypothalamus shuts down production of the releasing hormone and the pituitary gland shuts down secretion of the stimulating hormone.
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21
Q

Outline the two parts of the pituitary gland and their roles.

A
  • Anterior pituitary gland = releases ACTH which regulates levels of cortisol
  • Posterior pituitary gland = responsible for releasing hormone oxytocin which is crucial for infant/mother bonding
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22
Q

Describe the adrenal glands.

A

We have two adrenal glands situated on top of the kidneys. Each adrenal gland is made up of two distinct parts.

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23
Q

Outline the two components of the adrenal gland and their functions.

A

Adrenal cortex
- The outer section of the adrenal gland
- produces cortisol when experiencing long-term stress
- cortisol is also responsible for cardiovascular system: increases blood pressure and causes vessels to contrict

Adrenal medulla
- Inner section of adrenal gland
- excretes adrenaline in acutely stressful situations
- responsible for fight-or-flight response
- stops digestion, increases heart an breathing rate, reduces salivation, diverts blood away from skin, dilates pupils

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24
Q

Outline the sympathomedullary pathway.

A
  • The sympathomedullary pathway is a way for the body to deal with acutely stressful situations and triggers the fight or flight response
  • The sympathetic nervous system is triggered by the hypothalamus
  • The hypothalamus also sends a signal to the adrenal medulla to produce adrenaline and excrete it into the bloodstream
  • Once the threat has passed, the PNS dampens the stress response
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25
Q

List all of the functions of adrenaline in fight or flight.

A
  • Increases breathing and heart rate
  • Reduces salivation
  • Dilates pupils
  • Stops digestion
  • Increases oxygen in blood flow
  • Diverts blood flow away from skin and towards brain (rapid response planning) and skeletal muscles (physical action)
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26
Q

Evaluate fight or flight response.

A

ADV 1:

  • Makes sense from an evolutionary standpoint as the fight-or-flight response would increase an individual’s chance to survive
  • so they are more likely to carry on that trait to the next generation

ADV 2:

  • Research evidence to support it
  • Studies into adrenal glands show that people with malfunctioning adrenal glands do not have a normal fight-or-flight response
  • Supports role of adrenaline in fight or flight

DIS 1:

  • Gray (1988) suggests that we not only fight or flight but we also freeze
  • This involves stopping, looking, listening and being hyper-vigilant to danger

DIS 2:

  • Taylor (2000) indicated that this doesn’t account for gender differences. Instead of fight or flight, women tend to tend-and-befriend
  • This involves seeking out social groups for mutual defence and protecting their offspring
  • This is because they have the hormone oxytocin
  • Dawans (2012) states men also tend and befriend however during the September 11th 2001 attacks both men and women showed tend and befriend as they tried to contact loved ones and help one another.
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27
Q

Define localisation of function.

A

The principle that specific functions have specific locations within the brain.

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28
Q

Describe the visual centres of the brain and outline visual processing.

A
  • The visual cortex processes information to do with colour and shape
  • It is located in the occipital lobe of both hemispheres
  1. Visual processing begins at the retina and light strikes the photoreceptors in the retina
  2. Nerve impulses from the retina are transmitted to the brain via the optic nerve
  3. Majority of the nerve impulses terminate at the thalamus which acts as a relay station and passes information on to visual cortex
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29
Q

Describe the auditory centres of the brain and outline auditory pathway.

A
  • Auditory cortex processes information to do with pitch and volume
  • Located in temporal lobe of both hemispheres
  1. Sound waves are converted into nerve impulses in the cochlea
  2. Nerve impulses transmitted to brain via auditory nerve
  3. Basic decoding occurs in brain stem, thalamus carries out further processing before impulses are passed to the auditory cortex
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30
Q

Outline the motor cortex in detail.

A
  • Motor cortex is responsible for voluntary movement
  • Located in frontal lobe of both hemispheres
  • Different areas of the motor cortex correspond to different parts of the body
  • Damage to motor cortex can lead to paralysis or loss of muscle function
31
Q

Outline the somatosensory cortex.

A
  • Responsible for processing sensations such as pain and pressure
  • Located in the parietal lobe of both hemispheres
32
Q

Explain the Broca’s area.

A
  • Responsible for speech production
  • Found lesions in LEFT hemisphere of frontal lobe and patients had impaired speech
  • Damage causes Expressive Aphasia
  • Difficulty with words that help sentences function e.g. it, the etc. and lacks fluency
33
Q

Explain Wernicke’s area.

A
  • Responsible for speech perception
  • Lesions found in LEFT hemisphere of temporal lobe
  • Damage causes Receptive Aphasia impaired ability to process and understand language
34
Q

Give three drawbacks of localisation of function.

A

DIS 1:

  • Dronkers et al (2007)
  • Re-examined preserved brains from Broca’s patients
  • MRI scans indicated lesions in several areas of the brain
  • Lesions in Broca’s area causes temporary speech disruption and usually doesn’t result in severe speech impairment
  • Language is more widely distributed and less localised than we thought

DIS 2:

  • Individual differences in brain areas for certain functions
  • Different brain areas are activated when a person is engaged in silent reading
  • Observed activity in right temporal lobe, left frontal lobe and occipital lobe
  • Therefore silent reading has no specific area in the brain

DIS 3:

  • Some functions are more localised than others.
  • Motor and somatosensory functions are highly localised to specific areas of the cortex.
  • higher functions (e.g. personality and consciousness) are much more widely distributed.
  • Functions such as language are too complex to be assigned to just one area and instead involve networks of brain regions.
35
Q

Define hemispheric laterisation.

A

The notion that certain functions are principally governed by one side of the brain.

36
Q

Describe hemispheric lateralisation in detail.

A
  • In most people language centres are governed by the left hemisphere.
  • The right hemisphere is dominant for visio-spatial functions and facial recognition
  • Right side is responsible for the left side of the body and left is responsible for the right side of the body
  • Right-sided paralysis means lateralised damages to the left hemisphere
  • The two hemispheres are connected by a bundle of nerve fibres called the corpus callosum which allows information to be communicated between the two halves
  • Two hemispheres work together to form most tasks part of a highly integrated system
37
Q

Evaluate Hemispheric lateralisation

A

ADV 1: Evolutionary standpoint
- Makes sense from evolutionary viewpoint
- Hemispheric lateralisation increases neural processing capacity which is adaptive
- Using one hemisphere to engage in a particular task leaves other to engage in another function
- Rogers et al (2004) hemispheric lateralisation in chickens is associated with ability to perform two task simultaneously (finding food and being vigilant for predators)

ADV 2: Evidence
- Patients with extensive damage to the left hemisphere can experience global aphasia (loss of speech production and perception)
- Suggests language is lateralised to the left hemisphere

DIS 1: JW Split brain patient
- Developed capacity to speak with right hemisphere but more fluent in left
- They made him speak about information presented in either the right or left visual field
- So language is not entirely lateralised to the left
- This is a single case study so we cannot generalise the findings

DIS 2: EB case study
- Virtually all of the left hemisphere was removed at age of two due to benign tumour
- His everyday language in terms of vocab and grammar was almost normal
- Systematic testing revealed subtle grammar errors and lower than normal scores in picture naming and reading loan words
- So language function can be largely preserved after removal of left but right hemisphere cannot provide a perfect mastery of language

38
Q

Outline the procedure of split-brain research.

A
  • Patients asked to stare at a dot in the centre of a screen
  • Information is presented in either the left or right visual field
  • Asked to make responses with either left hand (right hemisphere) or right hand (left hemisphere) or verbally (left hemisphere) without seeing what their hands are doing
  • e.g. if a dog is flashed in right visual field, they will be able to verbally answer dog as info goes to left hemisphere containing the language centres
  • e.g. if a cat flashed in left visual field they can draw a cat as info goes to right hemisphere
39
Q

Evaluate split-brain research.

A

ADV: Scientific

  • Experiments on split-brain patients are highly controlled and scientific

DIS 1: Drug therapy

  • Split-brain patients have often had drug therapy for their epilepsy for much longer than others
  • This may affect the way their brain works
  • Findings of split-brain research cannot be generalised

DIS 2: Idiographic approach

  • As few as three participants
  • Lacks population validity and not representative so cannot be generalised

DIS 3: Lacks ecological validity

  • Data from this research is very artificial
  • In the real work a severed corpus callosum can be compensated for by the unrestricted use of both visual fields
40
Q

Define brain plasticity.

A
  • The brain’s ability to change and adapt as a result of experience.
  • Plasticity allows the brain to cope better with the indirect effects of brain damage e.g. swelling or haemorrhage or inadequate blood supply from a stroke
41
Q

Describe the effect of life experiences on grey matter.

A
  • Nerve pathways used frequently develop stronger connections and those rarely used, die
  • By developing new connections and reducing weak ones, the brain is able to adapt to a changing environment
  • Boyke et al (2008) taught 60 year olds how to juggle and this increase grey matter in the visual cortex
42
Q

How do video games affect grey matter?

A
  • Kuhn et al (2014) compared a control group to a group that had video game training for at least 30 mins a day for the last two months
  • Playing games caused a significant increase in grey matter in visual cortex, hippocampus and cerebellum
  • Playing results in new synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory and motor performance
43
Q

Describe how meditation affects grey matter.

A
  • Davidson et al (2004) compared 8 practitioners of Tibetan meditation with ten students with no previous meditation experience
  • EEG picked up greater gamma wave activity in the monks even before they started meditating
  • Gamma waves coordinate neural activity
44
Q

Define functional recovery.

A

Form of plasticity where following damage caused by trauma, the brain can redistribute or transfer functions usually performed by damaged area to other undamaged areas

45
Q

Describe how functional recovery takes place and measures to maintain it.

A
  • Transfer from damaged areas to undamaged areas is called neural reorganisation
  • Growth of new neurons or connections to compensate for damaged areas is called neural regeneration
  • Axon sprouting is a part of neural regeneration where new nerve endings grow and connect with other undamaged nerve cells to form new neural pathways
  • Spontaneous recovery from a brain injury tends to slow down after a few weeks so physiotherapy is required to maintain improvements in functioning
  • Physiotherapy includes movement therapy and electrical stimulation to counter deficits in motor and cognitive functioning experienced after following a stroke
46
Q

Give two advantages of functional recovery.

A

ADV 1: Phantom Limb Syndrome

  • PLS is the continued experience of sensation in a missing limb as if it were still there
  • Sensations are often unpleasant and painful
  • PLS is caused by neural reorganisation in the somatosensory cortex that occurs because of limb loss

ADV 2: Research evidence

  • Sewed one eye of a kitten shut and analysed the brain’s cortical response
  • Visual cortex was not idle for shut eye as it continued to process information from the open eye
  • The brain areas reorganise themselves to adapt their functions
47
Q

What are the methods used to study the brain?

A
  • Post-mortem examinations
  • Functional Magnetic Resonance Imaging
  • Electroencephalogram (EEG)
  • Event-related potentials
48
Q

Outline post-mortem examinations.

A
  • Studying person who displays interesting behaviour while they are alive
  • When they die, psychologists look for abnormalities in the brain which may explain the behaviour through physical examination
49
Q

Evaluate post-mortem examinations.

A

ADV 1: Detailed examination

  • More detailed examination of anatomical and neurochemical aspects of the brain that wouldn’t be possible with other methods
  • Enables researchers to examine deeper regions such as hippocampus or hypothalamus

DIS 1: Lack validity

  • People die in a variety of ways and varying stage of disease
  • Length between death and post-mortem and drug treatments can affect brain and affect validity of research

DIS 2: Generalisability

  • Very small sample size as special permission needs to be granted to allow post-mortems
  • Cannot say sample is representative of the target population
  • Problematic to generalise findings to wider population
50
Q

Outline functional magnetic resonance imaging.

A
  • Provides an INDIRECT measure of neural activity
  • Can monitor blood flow in the using magnetic fields and radio waves
  • Measures change in energy released by haemoglobin (oxygen consumption) to create a moving picture of activity in the brain
  • Activity for specific functions of interest can be compared to a base-line task
51
Q

Evaluate fMRIs

A
  • ADV 1: captures dynamic image of the brain as opposed to post-mortems which only provide knowledge of the physiology
  • ADV 2: high spatial resolution (refers to smallest unit that can be measured)
  • DIS 1: interpretation is complex and affected by low temporal resolution (resolution of measurement against time), biased interpretation and base-line task used
  • DIS 2: very expensive to carry out research with, small sample size, issues with validity and generalisation
52
Q

Describe Electroencephalograms.

A
  • DIRECTLY measures GENERAL neural activity in the brain typically linked to sleep and arousal
  • Electrodes are placed on the scalp and measure neuronal activity directly below where it is placed
  • An EEG pattern can be formed when graphing electrical signals from various electrodes against time
  • Epilepsy patients would show spikes in their EEG pattern
  • Slowing of electrical activity would be shown in people with brain damage
53
Q

Outline the brain waves and functions.

A
  1. Gamma waves = concentrating, focusing and learning
  2. Beta waves = most activities while awake
  3. Alpha waves = while relaxed or sleepy
  4. Theta waves = stage 1 and 2 of sleep (light sleep)
  5. Delta waves = stage 3 of sleep (deep sleep and REM)
54
Q

Evaluate EEGs

A
  • ADV 1: useful in clinical diagnoses; helps doctor confirm seizures and diagnose patients with epilepsy
  • ADV 2: Cheaper so it can be used more widely in research, higher sample size, more validity
  • DIS 1: low spatial resolution
55
Q

Explain event-related potentials.

A
  • ERPs DIRECTLY measure neural activity in response to a SPECIFIC stimulus introduced by the researcher
  • Event Related Potentials cannot be easily distinguished from other signals generated in the brain so many presentations of the stimulus are required and electrical signals are averaged together
  • Extraneous neural acitivity will not consistently show up but the ERPs for the stimulus will
56
Q

Evaluate ERPs

A
  • ADV 1: Measures the processing of a stimulus even when there is no behavioural response so we can covertly measure the processing of a stimulus
  • ADV 2: Cheaper than fMRIs so can be used more widely in research
  • ADV 3: High temporal validity
  • DIS 1: Poor spatial validity
    DIS 2: Cannot measure neural activity deep within the brain in regions such as hypothalamus or hippocampus as only sufficiently strong voltage changes across the scalp are recordable. Restricted to the neocortex
57
Q

Define biological rhythms.

A

Cyclical changes in our physiological systems.

58
Q

Define circadian rhythms and explain how they function.

A
  • Circadian rhythms are any cycle that lasts 24 hours
  • They are driven by the suprachiasmatic nuclei (SCN) which is a pacemaker
  • This pacemaker is reset continually through photoentrainment - light is an input to the system, setting the SCN to the correct time
  • The SCN coordinates all circadian rhythms in the body e.g. sleep-wake cycle
59
Q

Outline the sleep-wake cycle as a circadian rhythm.

A
  • Light and darkness are external determiners of when we sleep and wake up
  • Strongest drives to sleep occur at 2-4 am and 1-3 pm
  • Melotonin levels are at their peak during hours of darkness
  • It is excreted from the pineal gland and induces sleep by inhibiting neural mechanisms that promote wakefulness
  • Light suppresses production of melotonin
  • Sleep and wakefulness are also under homeostatic control. This homeostatic drive for sleep increases gradually throughout the day, reaching its maximum in the late evening.
  • Circadian rhythms keep us awake as long as there is daylight and induce sleep in darkness whereas homeostasis makes us sleepier longer we are awake regardless of light
60
Q

What is the advantage of ciradian rhythms?

A

Real applications

  • Practical application in chronotherapeutics
  • Drugs need to be released in the right concentration at the target area and at the time it is needed most to be effective
  • The risk of heart attack is highest in the early hours of the day
  • A person with high risk of heart attack can take medication before sleeping and it will be released at the vulnerable time of 6 am
61
Q

Outline the three drawbacks of circadian rhythms.

A

DIS 1: Individual differences

  • Lengths of circadian rhythms can vary vastly from as little as 13 hours up to 165 hours
  • Further research should be done accounting for these extreme individual differences (Czeisler et al 1999)
  • Some people are ‘morning people’ and are able to rise early and sleep early while others prefer to sleep late and rise late

DIS 2: Arctic Regions

  • Studies of people living in the Arctic regions show normal sleeping patterns despite the prolonged exposure to light throughout the 24 hours of the day
  • Suggests that the exogenous zeitgeber of light as much has little bearing on our biological systems

DIS 3: Artificial light

  • Our circadian rhythms were believed to not be affected by artificial light but research proves otherwise
  • Czeisler et al (1999) altered a participants circadian rhythms down to 22 hours and up to 28 hours using artifical light
62
Q

Define Ultradian rhythms.

A

Biological cycles that last less than 24 hours e.g. Basic Rest Activity Cycle.

63
Q

Describe the BRAC as an ultradian rhythm.

A
  • Basic Rest Activity Cycle
  • 90 minute cycle where you progress through the five stages of sleep from light sleep to deep sleep and REM sleep
  • These 90 minute cycles repeat in our sleep
  • BRAC continues through our day as stage progress from altertness to physiological fatigue (tiredness, hunger and loss of concentration)
64
Q

Find one advantage and disadvantage of ultradian rhythms.

A

ADV 1: Support

  • Ericsson found that elite groups of violinists limit their practice sessions to 90 minutes
  • VIolinists frequently napped to recover from practise and more skilled ones napping more
  • Also found amongst athletes, chess players and writers
  • Fits with BRAC

DIS 1: Individual differences

  • It was found that there are individual differences in ultradian rhythms that are biologically determined or genetic
  • Pps observed when sleeping in a lab over 11 consecutive nights
  • Found differences in sleep duration, time taken to fall asleep and time spent in each stage
65
Q

Define infradian rhythms.

A

Biological cycles which last longer than 24 hours

66
Q

Describe the menstrual cycle as an infradian rhythm.

A
  • On average lasts around 28 days
  • Regulated by hormones
  • Ovulation occurs around halfway through cycle and lasts 16-32 hours when oestrogen levels are at the peak
  • Following ovulation, progesterone levels rise to prepare the uterus for possible implantation of an embryo
67
Q

Give one advantage and one disadvantage of infradian rhythms.

A

ADV 1: Influence on behaviour

  • Infradian rhythms can have an influence on behaviour
  • Research found that women usually prefer feminised male faces when looking for a long-term partner
  • But during ovulation they prefer masculine faces

DIS 1: Other factors

  • Menstrual cycle is not only determined by infradian rhythms
  • When a group of women live together without contraceptives, their menstrual cycle can synchronise
  • Sweat samples taken from one group of women and rubbed on upper lip of another group and groups menstrual cycles synchronised
  • Can be influenced by pheromones
  • Pheromones are chemicals released by animals into the environment which affect the behaviour of other animals of the same species
68
Q

Describe one example of an endogenous pacemaker and its function.

A
  • Suprachiasmatic nuclei
  • A cluster of nerve cells in the hypothalamus
  • Responsible for generating and maintaining circadian rhythms in the body
  • Neurons within the SCN synchronise with each other so neurons at other sites in the body recieve time-coordinated signals
  • Built-in circadian rhythm that only needs to be adjusted when there is a change in external light levels
  • Also regulates manufacture and excretion of melotonin
69
Q

Give an advantage and disadvantage of endogenous pacemakers,

A

ADV 1: No need for exogenous zeitgebers

  • Kate Aldcroft stayed in a university laboratory for 25 days with no access to exogenous zeitgebers
  • Her core temperature cycle remained at 24 hours
  • So we do not need exogenous zeitgebers

DIS 1: Need for exogenous zeitgebers

  • However her sleep-wake cycle extended from 24 hours to 30 hours with periods of sleep as long as 16 hours
  • Suggests that we do need it to maintain internal biological rhythms of sleep
69
Q

Outline exogenous zeitgebers and give and example of one and its functions.

A
  • Exogenous zeitgebers are environmental events responsible for maintaining the biological clocks of organisms
  • Light resets the circadian rhythms in the SCN through photoentrainment to keep it on a 24 hour clock
70
Q

Describe what happens when pacemaker and zeitgebers are out of sync.

A
  • When people move to night shift or move countries, their endogenous pacemaker attempts to impose in-built rhythm of sleep
  • But this would be out of sync with the exogenous zeitgeber of light
  • Out of sync biological rhythms leads to disrupted sleep patterns, increased anxiety and decreased alertness and vigilance
71
Q

Evaluate exogenous zeitgebers.

A

ADV 1: Blind people

  • Supported as blind people with light perception are still able to have normal, regular sleep patterns
  • Blind people without light perception have abnormal circadian rhythms
  • Shows vital role of exogenous zeitgeber of light on circadian rhythms and sleep

ADV 2: Travel

  • Lots of exposure to light before an east-west flight can reduce the time required to adjust our circadian rhythms to local time
  • Importance of light to adjust circadian rhythms to environment

DIS 1: Arctic Studies

  • Studies of people living in the Arctic regions show normal sleeping patterns despite the prolonged exposure to light throughout the 24 hours of the day
  • Suggests that the exogenous zeitgeber of light as much has little bearing on our biological systems
72
Q
A

AQA A-Level Psychology (18 decks)

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