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119 Cards in this Set
- Front
- Back
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The nervous system |
The highway made up of neurons along which your brain sends and receives information about what is happening to the body and around it. Our primary internal communications systems. 2 main functions: Collect, process and respond to information Co-ordinate organs and cells |
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Central nervous system |
Consists of the brain and spinal cord Brain- provides conscious awareness, there are 2 hemispheres and th brain system connects the brain and spinal cord Spinal cord- an extension of the brain, transfers messages to and from the brain and the rest of the body and is responsible for simple reflex actions which don't involve the brain |
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Peripheral nervous system |
Relays messages (nerve impulses) from the CNS to the rest of the body to the rest of the body |
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Somatic nervous system (peripheral nervous system) |
Maintain communication between the CNS and outside senses Made up of sensory receptors which carry information to the spinal cord and brain Made up of motor pathways which control movement and muscle responses |
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Autonomic nervous system (peripheral nervous system) |
Unconscious Plays an important role in homeostasis which maintains internal processes like body temperature, heart rate and blood pressure Only consists of motor pathways 2 components: sympathetic and parasympathetic nervous system |
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Sympathetic nervous system (peripheral nervous system) |
Involved in responses that prepare the body for fight or flight Impulses travel from system to organs to help us prepare for actions Actions are antagonistic and works in opposition to parasympathetic nervous system |
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Parasympathetic nervous system (peripheral nervous system) |
Relax body or return us to normal resting state such as heart rate slowed Any previous slowed functions started again Rest and digest |
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Endocrine system |
Is in charge of body processes that happen slowly such as cell growth. Produce hormones that are released into the bloodstream and affect the cell that has the receptor Works together with the nervous system |
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Pineal gland (endocrine system) |
Releases melatonin Responsible for biological rhythms including the sleep cycle |
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Hypothalamus (endocrine system) |
Important in fight or flight Stimulates and controls release of hormones from the pituitary gland |
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Thyroid gland (endocrine system) |
Releases thyroxine Regulating metabolism |
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Pituitary gland (endocrine system) |
Master gland because hormones released control and stimulate the release of hormones from other glands |
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Adrenal gland- medulla (endocrine system) |
Release adrenaline and noradrenaline Hormones in fight or flight response |
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Adrenal gland- cortex (endocrine system) |
Releases cortisol Stimulates release of glucose to provide energy while suppressing the immune system |
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Ovaries (endocrine system) |
Release oestrogen Controls regulation of female reproductive system |
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Testes (endocrine system) |
Release testosterone Development of male characteristics during puberty such as muscle growth |
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Endocrine glands |
Produce and secrete chemicals and hormones that regulate the activity of cells or organs Each gland produces different hormones Is regulated by feedback which enables stable concentrations of hormones in the bloodstream |
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Hormones |
Circulate bloodstream and carried to target sites Only affects target cells due to certain receptors Timing of hormone release is critical for normal functioning |
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Neurons |
Cells that are specialised to carry neural information throughout the body. There are sensory, motor and relay neurons- Moves electrical impulses to and from the CNS |
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Relay neuron |
Allow sensory and motor neurons to communicate with each other Found within the brain and spinal cord Short dendrites and short or long axons |
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Motor neurons |
Form synapses with muscles and control contractions Release neurotransmitters that bind to receptors and triggers respond of muscle movement Found in CNS but project axons outside to directly or indirectly control muscles Short dendrites and long axons |
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Sensory neurons |
Carry nerve impulses from sensory receptors to spinal cord and brain Converts information from receptors to impulses Long dendrites and short axons Found in sensory receptors |
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Structure of a typical neuron: cell body |
Metabolic centre of the neuron |
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Structure of a neuron: dendrites |
Short processes emanating from the cell body which recieves most of the synaptic contacts from other neurons |
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Structure of a neuron: axon hillock |
The cone shaped region at the junction between the axon and th cell body |
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Structure of the neuron: axon |
The long, narrow process the projects from the cell body |
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Structure of a neuron: cell membrane |
The semipermeable membrane that encloses the neuron |
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Structure of the neuron: myelin sheath |
The fatty insulation around many axons |
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Structure of the neuron: nodes of Ranvier |
The gaps between sections of myelin |
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Structure of a neuron: axon terminal buttons |
Buttonlike endings of the axon branches, which release chemicals into synapses |
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Structure of a neuron: synapse |
The gaps between adjacent neurons across which chemical signals are transmitted |
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Thee reflex arc: knee jerk reflex |
A stimulus such as a hammer hits the knee This is detected by sense organs in the PNS which convey a message along sensory neurons The message reaches the CNS where it connects with a relay neuron This then transfers the message to a motor neuron This then carries the message to an effector such as a muscle which causes the muscle to contract and cause the knee to move or jerk |
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Synaptic transmission |
An action potential is an electrical signal which occurs when a neuron sends information down an axon, away from the cell body. once the action potential arrives at the terminal button it's transferred to another neuron via chemical messengers known as neurotransmitters Signals within neurons are transmitted electronically where as signals between neurons are transmitted chemically by synaptic transmission |
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Process of synaptic transmission |
Nerve impulses travel down axon Nerve impulse reaches synaptic terminal at present synaptic membrane This triggers the release of neurotransmitters which are fired into the synaptic cleft Neurotransmitters binds with the receptor on the dendrites of the post synaptic neuron Postsynaptic receptors are activated by transmitters and an increase/decrease likelihood that the post synaptic neurone will fire an action potential Eventually neurotransmitters are cleared from the cleft via reuptake or via enzymes breaking down the neurotransmitter |
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Summation |
A nerve cell can receive both EPSPs and IPSPs simultaneously. These are summed and if the net effect on the post synaptic neuron miss inhibitory the neuron will be less likely to fire. If the net effect is excitatory effect the neuron will be more likely to fire. |
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Excitation |
Occurs when the receptor stimulation results in an increase in the positive charge of the postsynaptic neuron and increases the likelihood of the neuron firing and passing on the electrical impulses This is known as EPSP Examples: noradrenaline and acetylcholine |
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Inhibition |
Occurs when a receptor stimulation results in an increase of the negative charge of the postsynaptic neuron and decreases the likelihood of the neruon firing and passing on electrical impulses This is known as IPSP Example: GABA and serotonin |
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Fight or flight response |
Is individual threat Amygdala mobilised Amygdala associates sensory signals with emotions such as fear and anger which are associated with fight or flight Amygdala sends a distress signal to hypothalamus Hypothalamus communicates with the rest of the body through triggering activity in the sympathetic branch of the autonomic nervous system ANS changes from the normal resting state (parasympathetic state) to the psychologically aroused sympathetic state. The sns sends a signal through the adrenal medulla which releases adrenaline into the bloodstream Adrenaline circulates the body causing physiological changes In general adrenaline prepares the body for fight or flight increasing oxygen in the brain and blood supply to the muscles. Direct effects of adrenaline include increasing heart rate, breathing rate and blood pressure, inhibited digestion and saliva production Once the threat is over the PNS dampens down the threat response and returns the body to its resting state, slowing heart beat, reducing blood pressure and starting digestion |
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The fight orb flight explanation doesn't fully explain the stress response in females |
Taylor et al - tend and befriend response in stressful situations. Women are more likely to protect their offspring or form alliances with other women rather than fight an adversery or flee So the original fight or flight response has limited application but this has prompted more research providing an alternative explanation applicable to females Highlights beta bias as they assumed females respond in the same way to males |
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One issue with the fight or flight explanation is that human behaviour is limited to just 2 responses. |
Research suggests the first response to danger is to avoid confrontation altogether which is demonstrated by a freeze response This suggests that the fight or flight explanation is limited and doesn't fully explain the complex cognitive and biological factors that underpin the human response to stress This is reductionist because the theory oversimplifies human behaviour or cognitive processes involved in the fight or flight response as it neglects to explain the complexities of the mind |
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There may be a genetic basis for gender difference in fight or flight response |
Researchers found the SRY gene found in the Y chromosome directs male development promoting aggression and resulting in fight or flight reponse for stress - gene may prime males to respond to stress in this way by the release of the stress hormone such as adrenaline He lack of SRY gene in females together with the action of oestrogen and oxytonin may be why they don't show the fight or flight response of stress This shows biological determinism because behaviour is explained in terms of genes such as SRY gene and hormones such as oestrogen |
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Lateralisation of the brain |
The division of tasks between 2 hemispheres. Language= left hemisphere Creative tasks= right hemisphere Broca and Wernicke's found that the 2 hemispheres aren't equivalent in terms of the cognitive tasks they perform. |
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Corpos callosum |
A bundle of nerve fibres that connects the left and right hemisphere and carry most of the communication between 2 halves. |
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Epileptic seizure |
Caused when there's a storm of electrical activity in the brain. When a seizure happens electrical impulses spread rapidly to the hemisphere on the other side via the corpus callosum. |
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Sperry (lateralisation of the brain research) |
Hemisphere deconnection and unity in conscious awareness. Epileptic paitents have their hemispheres deconnected to stop the spreading of electrical impulses to reduce impacts of fits. Sperry was able to study these split brain paitents to determine whether there's a difference between the 2 hemispheres. His major contribution to this area was the design of apparatus that allowed information to be sent to just one hemisphere. 11 split brain paitents
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Visual stimuli presented to one visual field |
Method: Asked participants to respond to visual information Blindfolding one of the participants eyes and asking them to fixate with the seeing eye Researchers projected a stimulus either on the left or right hand side of the fixation point for 1/10 sec so they didn't have time for eye movement Asked what they had seen on the screen Results: When a picture of an object was shown to paitents right visual field the paitents could easily describe what was seen Left visual field couldn't describe what they saw and reported there was nothing there this was due to a lack of language centres in the right hemisphere In the normal brain,messages from the right hemisphere would be relayed to language centres in the left hemisphere |
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Visual stimuli presented to both visual fields including composite words |
Method: Symbols and words were flashed to both visual fields- the subject would look at the fixation point on the screen while 2 symbols or words were flashed either side of the fixation point Results: If 2 words were presented simultaneously one on either side of the visual field, the paitent would write with their left hand the word key and say the word ring |
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Tactile investigations |
Method: Following the procedure of visual tasks Asked participants to select that matching objects from a grab bag Paitents hands hidden behind screen Objects were placed in both hands and participants were asked to find the object which had been in each hand in the grab bag Results: Couldn't attach verbal labels to objects projected in the left visual field they were able to select a matching object from a grab bag using their left hand Left hand able to select an object that was most closely associated with objects on the left visual field in each case the paitent wasn't able to verbally identify what they had seen but could nethertheless understand what the object was using the right hemisphere and select the corresponding object accordingly |
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Functional magnetic resonance imaging (fmri) |
Measures brain activity while a person is performing a task at uses MRI technology Detects changes in blood oxygenation and flow as a result of brain activity Brain area more active- consumes more oxygen- blood directed to active area Produces 3D activation maps which shows which parts of the brain are involved in particular mental processes Allows us to understand more about localisation of function in the brain |
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Strengths of FMRI |
Doesn't rely on use of radiation Risk free Straightforward to use Produces images that have very high spatial resolution so it provides a clear picture of how brain activity is localised |
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Weaknesses of FMRI |
Expensive Only capture clear image if person stays perfectly still Poor temporal validity due to 5 second time lag Can only measure blood flow and not individual activity of neurons so it's difficult to see what brain activity is represented on the screen |
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Electroencephalogram (EEG) |
A record of tiny electrical impulses produced by brain activity Measuring characteristics wave patterns can help diagnose some brain conditions Measures electrical activity via electrodes that are fixed to the skull using a skull cap Scan represents brain wave patterns generated by neurons Used as a diagnostic tool as unusual arrhythmic patterns of activity may indicate neurological abnormalities such as epilepsy |
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Strengths of EEGs |
Many scientific and clinical applications Diagnosis of conditions such as epilepsy Contributed to understanding of stages involved in sleep High temporal resolution |
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Weaknesses of EEGs |
In raw form it's a crude and overly general measure of brain activity. Generalised nature of the information recieved Signal not useful for pinpointing exact source of neural activity Doesn't allow researchers to distinguish between activities originating in different but adjacent locations. |
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Event related potentials (ERPs) |
The brains electrophysiological response to a specific sensory, cognitive or motor event can be isolated through statistical analysis of EEG data All extraneous brain activity from EEG recording is filtered out only leaving related responses What remains are event related potentials which are types of brainwave triggered by a particular event |
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Strengths of ERPs |
Bring more specificity to neural processes than raw EEG data Excellent temporal validity which has led to widespread use in measurement of cognitive functions and deficits Able to identify different types of ERPs and precise roles |
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Weaknesses of ERPs |
Lack of standardisation in ERP methodology between different research studies which make it difficult to confirm findings Not easy to eliminate background noise and extraneous variables so hard to establish pure data in ERP studies |
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Post mortem examinations |
Brain is analysed after death to determine whether certain observed behaviours during a paitents lifetime can be linked to abnormalities in the brain Brains are likely to be from people who had a rare disorder and experienced unusual deficits in mental processes Involve comparison with a neurotypical brain in order to ascertain extent of difference |
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Post mortem strengths |
Vital in providing a foundation for early understanding of key processes in the brain Broca and Wernicke's relied on post mortem studies in establishing links between language, brain and behaviour before neuroimaging became possible Improve medical knowledge and help generate hypotheses for further studies |
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Post mortem weaknesses |
Issue with causation Observed damage to the brain may not be linked to the deficits under review but some other trauma or decay Ethical issues of consent from the paitent before death so may not be able to provide informed consent |
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Localisation of brain function |
The theory that different areas of the brain are responsible for particular functions |
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The cerebrum (localisation) |
Regulated our higher intellectual processes Made up of the left and right hemisphere Some physical and psychological functions are controlled or dominated by one hemisphere called lateralisation |
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Motor cortex (localisation) |
Back of frontal lobe. Controls voluntary movement in opposite sides often body Damage can lead to loss of control in fin movements |
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Broca's area (localisation) |
Area of the frontal lobe of the brain in the left hemisphere Responsible for speech production Damage causes Broca's aphasia which is characterised by slow speech and lack of fluency |
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Somatosensory cortex (localisation) |
Found in both of the parietal lobes Seperated by the motor area by a valet called the central sulcus Processes sensory information such as touch Amount of somatosensory area devoted to a particular body part denotes it's sensitivity |
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Occipital lobe (localisation) |
Visual cortex At the back of the brain Each eye sends information from the right visual field to the left visual cortex and from the left visual field to the right visual cortex |
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Temporal lobe (localisation) |
Auditory area Analyses speech based information Damage may produce partial hearing loss |
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Wernicke's area (localisation) |
Part of the frontal and temporal lobe Inthe left hemisphere Responsible for speech production Damages may affect ability to comprehend language Damage can result in Wernicke's aphasia which results in them making up nonsense words |
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Functional recovery |
A form of plasticity following damage through trauma. The brains ability to redistribute or transfer functions usually performed by a damaged area to other undamaged areas. |
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Ways the brain can recover |
Axonal sprouting- when new nerve endings grow and connect with other undamaged nerve cells so that new neural pathways are formed Reformation of blood vessels- new blood vessels are formed when others are damaged Recruitment of homologous areas- opposite sides of the brain can take on the role of other undamaged areas |
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Hubel and Wiesel research support |
Analysed responses in the brain of a kitten with one eye sewed shut. They found the area associated with the sewn eye continued to process information from the open eye which wasn't expected |
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Danelli- fuctional recovery |
A Italian boy who lost his linguistic abilities in the left hemisphere as he was right handed. Through rehabilitation by the time he was 17 when danelli tested him it was found that the right hemisphere had compensated for the loss of the left hemisphere but he still had problems identifying objects in pictures. So although, the right hemisphere compensated it wasn't a full compensation of all functions. |
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Functional recovery evaluation |
How long a person spends in school can influence their functional recovery Schneider found those who spent longer in education were more likely to make a full brain recovery with no permanent deficits This means that if the brain is more cognitively stimulated then it's recovery can be improved. However other factors may influence such as severity of injury, age and overall health. |
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Plasticity |
The brains ability to modify its own structure and function as a result of experience. |
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Research support for plasticity |
Maguire et al Studied brains of London taxi drivers and found a larger posterior hippocampus which is responsible for spatial and navigational skills. There's a positive correlation between time spent in the job and strength of neural connections This suggests the structure of the brain is larger as a result of experience Problems: Gender bias- male Has real life application Didn't measure hippocampus before being a taxi driver |
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Research support for plasticity |
Studied medical students who had their brains imaged for 3 months before and after final exams. He found there was noticeable difference in the posterior hippocampus. This suggests the structure of the brain is larger due to the learning they participated in. |
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Plasticity evaluation |
Practical application Neurorehabilitation created to assist those suffering from brain trauma which led to loss of function. Spontaneous recovery slows down after a few weeks so intervention is required to continue the process through methods such as movement therapy and electrical stimulation. This demonstrates its ability to fix itself but only to a certain extent. |
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Plasticity evaluation |
Negative plasticity Medina found that extensive drug use led to poorer cognition functioning and higher dementia risk which is known as maladaptation. |
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Plasticity evaluation |
Age and plasticity With age brain plasticity decreases. However, bezzola et al found that using fmri scans those within the age bracket of 40-60 who practised 40 hours of golf a week had reduced motor cortex activity compared to a control group which suggests the brain created more effective neural connections with practice supporting that plasticity continues throughout life. |
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Exogenous zeitgebers |
External cue that may affect or entrain our biological rhythms such as the influence of light on the sleep/wake cycle. Siffre spent 6 months in a cave without clocks or natural light. His sleep/wake cycle went from 24 hours to between 25-30 hours. This suggests the exogenous zeitgebers such as light are needed to keep our rhythms in sync. Exogenous zeitgebers are external factors in the environment that reset our biological clocks through a process known as entrainment. |
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Exegenous zeitgebers- light |
Receptors in the SCN are sensitive to changes in light levels during the day and use this to synchronise the activity of the body's organs and glands. Light resets the internal biological clock each day keeping it on a 24 hour cycle. It can reset the SCN so plays a role in the sleep/wake cycle. Light has an indirect influence on key processes in the body that control such functions as hormone secretion and blood circulation. |
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Exogenous zeitgebers research |
Campbell and Murphy Demonstrated that light may be detected by skin receptors even when the same information isn't recieved by the eyes. 15 participants were woken at various times and a light pad was shone at the back of their knees Researchers managed to produce a deviation in the participants usual sleep/wake cycle of up to 3 hours This suggests that light is a powerful exogenous zeitgeber that need not necessarily rely on the eyes to exert its influence on the brain |
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Social cues (exogenous zeitgebers) |
Meal times and social activities may have a role as zeitgebers. Infants sleep/wake cycle is random. 6 weeks the circadian rhythm begins and by about 16 weeks most babies are entrained. The schedules imposed by parents have a key influence such as adult determined meal times and bedtimes. Research suggests the adapting to local times for eating and sleeping is an effective way of entraining circadian rhythms to beat jetlag. |
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Exegenous zeitgebers evaluation |
Other factors may be involved not just light and social cues. A case study by miles investigated young blind man from broth with a circadian rhythm of 24.9 hours whose sleep/wake cycle couldn't be adjusted regardless of changes to social cues. His required medication to allow him to sleep and wake up everyday at the appropriate time. Studies of individuals who live in the artic regions showed normal sleep patterns. This means that circadian rhythms can be affected by other factors such as skin receptors. |
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Exegenous zeitgebers evaluation |
Findings from Campbell and Murphy have yet to be replicated. Critics have argued that there may have been some light exposure to participants eyes. This means hat results lack validity as there are confounding variables such as light exposure. Furthermore, isolating one exogenous zeitgebers doesn't allow us to understand the influence of other external influences and how they all interact. This means that results lack reliability as light effects results. |
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Endogenous pacemakers |
Internal body clocks that regulate many of our biological rhythms this suggests they are inherited. |
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The suprachiamastic nucleus (SCN) |
Has an influence on the sleep/wake cycle. This is because within the hippocampus there is the SCN which is believed to control the pineal gland which secretes the hormone melatonin which induces sleep. A tiny bundle of nerve cells located on the hypothalamus in each hemisphere in the brain. Is influential in maintaining circadian rhythms such as the sleep/wake cycle Lies just above the optic chiasm It recieves information about light directly from the optic chiasm which continues even when eyes are closed, enabling the biological clock to adjust to changing patterns of daylight while we sleep. |
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Research support endogenous pacemakers |
Decoursey et al- destoryed the SCN connection of 30 chipmunks observed in normal habitat for 80 days. Found the sleep/wake cycle disappeared and by the end a significant proportion of them had been killed by predictors. Ralph et al- bred mutant hamsters with a 20 hour sleep/wake cycle. When the SCN cells from the foetal tissue of mustn't hamsters were transplanted into the brains of normal hamsters, the cycles of the second group defaulted to 20 hours. Both these studies emphasise the role of the SCN in establishing and maintaining the circadian sleep/ wake cycle. |
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Pineal gland and melatonin (endogenous pacemakers) |
SCN recieves information about day length. It passes this information onto pineal gland. Production and release of melatonin from the pineal gland follows a circadian rhythm peaking during hours of darkness and dropping when it's light Melatonin uses a chemical that induces sleep and is inhibited during periods of wakefulness. The pineal gland is in the endocrine system. |
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Endogenous pacemakers evaluation |
The SCN role in the sleep/wake cycle has been demonstrated with animals through lesion studies and cellular implantation. Animals have been exposed to considerable harm and consequently serious risk when returned back to the wild. This is a problem because there are ethical issues because the animals were to considerable harm and risk when they were turned to their natural habitat in the decoursey study. There are also problems with generalisation because animals aren't the same as humans. However, it has provided an understanding of endogenous pacemakers such as the SCN. |
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Endogenous pacemakers evaluation |
There are other factors such as peripheral oscillators. Research has demonstrated that there are many peripheral oscillators kind in many other organs of the body such as the adrenal gland, oesophagus, lungs, liver, pancreas and skin that not only function in combination with the SCN they also have the ability to work independently. Damiola, demonstrated that changing the feeding patterns of mice could alter the circadian rhythm of liver cells by up to 12 hours, whilst leaving of the SCN unaffected. This suggests that the SCN isn't the only endogenous pacemakers as there are other pacemakers around the body that are independent of the SCN. This means that the SCN is over emphasised. |
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Overall... |
Looking at endogenous pacemakers in isolation only gives us an unrealistic view of human behaviour. In real life both endogenous pacemakers and exogenous zeitgebers interact suggesting that it makes little sense to look at them both seperatley in researchers. |
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Biological rhythms |
Cyclical changes in body activity. It has evolved due to the environment. All biological rhythms are governed by our internal body clocks (endogenous pacemakers) and external cues (exogenous zeitgebers). |
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Circadian rhythms |
A biological rhythms subject to a 24 hour cycle which regulates na number of body processes such as the sleep/wake cycle and changes in core body temperature. Other examples of human circadian rhythms include heart rate, metabolism and breathing. |
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Circadian rhythm example- core body temperature |
At highest at 6AM at 38 degrees and lowest at 4AM at 36 degrees Varies by 2 degrees May affect our mental abilities- warmer we are the better our cognitive abilities Folkard- children who had stories read at 3PM showed superior recall and comprehension after a week compared to children who heard the same stories at 9AM. Gupta- found improved performance on iq test at 7pm opposed to 2pm and 9am |
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Circadian rhythm example- sleep/wake cycle |
Daylight/ darkness is an important exogenous zeitgeber affecting our built in circadian rhythm. Aschoff and wever found when participants spent 4 weeks in a ww2 bunker deprived of natural light. They found all but 1 of the participants displayed a circadian rhythm between 24 and 25 hours. |
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Sleep/wake cycle siffre research |
Spent 2 months underground in the southern Alps caves to study the effects on his own biological rhythms Deprived to exposure to natural light and sound but had access to food and drink Had no way of telling time the time (calender or clock) but had access to an artificial light. Found: Siffre resurfaced in mid-september but believed it to be mid august Free running biological rhythm was around 25 hours though he continued to fall asleep and wake on a regular cycle Conclusion: our sleep/wake cycle might be slightly longer than 24 hours but it's entrained by exogenous Zeitgebers associated with our 24 hour day. |
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Sleep/wake cycle research |
Studied a group of 12 volunteers who agreed to live in a dark cave for 3 weeks retiring when the clock said 11:45 pm and rising when it said 7:45am. Over the course of the study researchers gradually sped up the study. He found only one participant was able to comfortably adjust to the new regime. This suggests the existence of a strong free running circadian rhythm that cannot easily be overridden by changes in the external environment (exogenous zeitgebers). |
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Circadian rhythm evaluation- practical application in shift work |
Shift work has found to lead to desynchronization of circadian rhythms and can lead to adverse cognitive and physiological effects. Research has shown that night workers suffer a concentration lapse of 6AM, increasing the likelihood of accidents and shift workers are also X3 more likely to suffer from heart disease as a result from the stress of adjusting to sleep/wake cycles. This has an economic implications as researchers have the knowledge to improve the sleep/wake cycle which has an implication in terms of how to best manage worker productivity. |
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Circadian rhythm evaluation - issue with evidence |
The sleep/wake cycle varies between people which has an impact on generalisation Folkards and Aschoff & Wevers study were conducted on only a handful of people. Czeisler et al have found evidence that individuals cycles can vary as much as 13-65 hours Siffre noted that age also affected findings as when he went into the cave at 60 his body responded very differently with his body clock flowing more of a 48 hour cycle. This means that individual differences and small sample sizes has an impact on findings because people involved may not be representative of the wider popualtion which limits the extent to which meaningful generalisation can be made and general conclusions can be drawn. |
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Circadian rhythm evaluation- poor control in studies |
The artificial light in circadian rhythms studies can act as a confounding variable to biological rhythms therefore having an impact on findings. It was assumed it was only natural light that has an influence on our biological rhythms but research by czeisler found that dim artificial lighting could adjust the circadian rhythm between 22-28 hours. Artificial light could therefore be a confounding variable in studies such as siffre. This means that results in some original studies may lack validity and the sleep/wake cycle may vary considerably more. Additionally, the impact of artificial lighting on our circadian rhythm also had practical implications when it comes to the use of electronic devices such as iPads and smartphones during different times of the day |
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Infradian rhythms |
A type of biological rhythm with a frequency of less than one cycle in 24 hours such as menstruations and seasonal affective disorders |
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Menstrual cycle |
Function is to overlate Cycle refers to the time between the first days of the woman's period to the day before her period Typical cycle= 28 days (lasts more than 24 hours) |
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Menstrual cycle process |
Hormones stimulate a follicle in one ovary to ripen an ovum and to release oestrogen. Once the ovum has ripened the follicle releases progesterone which causes the lining of the womb to prepare for pregnancy by increasing its blood supply. After 2 weeks after ovulation if there's no pregnancy, progesterone is reduced and this causes the lining of the womb to shed and the ovum is absorbed into the body. Although the menstrual cycle is an endogenous system evidence suggests that it's influenced by exogenous factors such as the cycle of other women. Its suggested this is due to pheromones. |
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Pheromones |
Chemical substance produced and released into the environment by an animal. It can be detected by the sense of smell. |
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Menstrual cycles may synchronise as a result of the influence of female pheromones |
McClintock Involved 29 women with a history of irregular periods Samples of pheromones were gathered from 9 women at different stages of their menstrual cycle via a cotton pad placed in the armpit phermones were picked up Pads were treated to be rubbed on the upper lip of the other participants Pads were worn for atleast 8 hours to ensure phermones were picked up Pads were treated to be rubbed on the upper lip of the other participants He found 68% of women experienced changes to their cycle which brought them closer to the cycle of their odour donor The onset of their period became 2 days closer over a 4-6 month period which is referred to as menstrual synchrony He found 68% of women experienced changes to their cycle which brought them closer to the cycle of their odour donor The onset of their period became 2 days closer over a 4-6 month period which is referred to as menstrual synchrony |
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Although there's no debate to be had in the fact that menstration is cyclical there's some controversy in the idea that pheromones influence the cycle |
The study findings seem impressive but with such a small sample of women it can't be claimed that results are significant. There are a number of uncontrolled confounding variables such as stress, diet and exercise which could explain the changes in the menstrual cycle as the relationship to the donor could be by chance. Studies rely on self report is means that the study offers very weak support for the concept of phermones as an influence upon the menstrual cycle. |
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Evolutionary basis of the menstrual cycle |
together and therefore fall pregnant around the same time. His would mean that new borns could be cared for collectively within a social group increasing the chances of the offspring survival. Bentley found women would concierge and give birth at the same time spray they would be on sync when breastfeeding. For our ancestors it!ay have been an advantageous for females to menstruate together and therefore fall pregnant around the same time. His would mean that new borns could be cared for collectively within a social group increasing the chances of the offspring survival.Bentley found women would concierge and give birth at the same time spray they would be on sync when breastfeeding.However, schank found if there are too many females cycling together within a social group this would produce more completion forte highest quality males and consequently lower the fitness of offspring. So therefore the evolutionary perspective may lack validity as the avoidance of synchrony would appear to be the most adaptive strategy and therefore naturally selected. menstruate together and therefore fall pregnant around the same time. His would mean that new borns could be cared for collectively within a social group increasing the chances of the offspring survival.Bentley found women would concierge and give birth at the same time spray they would be on sync when breastfeeding.However, schank found if there are too many females cycling together within a social group this would produce more completion forte highest quality males and consequently lower the fitness of offspring. So therefore the evolutionary perspective may lack validity as the avoidance of synchrony would appear to be the most adaptive strategy and therefore naturally selected. However, schank found if there are too many females cycling together within a social group this would produce more completion forte highest quality males and consequently lower the fitness of offspring. However, schank found if there are too many females cycling together within a social group this would produce more completion forte highest quality males and consequently lower the fitness of offspring. So therefore the evolutionary perspective may lack validity as the avoidance of synchrony would appear to be the most adaptive strategy and therefore naturally selected. So therefore the evolutionary perspective may lack validity as the avoidance of synchrony would appear to be the most adaptive strategy and therefore naturally selected. . |
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Seasonal affective disorders |
A depressive disorder which has a seasonal pattern of onset and s described and diagnosed by the DSM-5 Winter depression as symptoms are most apparent in winter Symptoms begin in autumn as days get shorter but disappears in summer . |
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Seasonal affective disorders symptoms |
Persistent and low mood Loss of pleasure and interest in normal activities Irritability and feelings of despair, guilt and worthless Sleeping longer and finding it hard to get up Craving carbs and gaining weight |
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Seasonal affective disorders causes |
Reduced exposure to sunlight stops the hypothalamus working the right way which affects the production of serotonin and melatonin. During the night, the pineal gland secretes melatonin until dawn when there's an increase in light. During the winter, the lack of light in the morning means this secretion process continues longer and this thought to have a knock on effect on the production of serotonin in the brain. |
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Practical applications: treatment of SAD using a phototherapy |
An effective treatment for the disorder is to spend time exposed to bright light from a light box during the winter months. Eastman et al- studied this treatment finding that using a light box relieved symptoms for 60% of sufferers. The light box is thought to reset melatonin levels. 32% of participants= placebo effect= response bias so you can't be sure drug therapy works which casts doubt Inthe chemical influence of the light box because it may have not been the thing affecting the paitent. |
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Ultradian rhythms |
A type of biological rhythm with a frequency of more than one cycle in 24 hours. For example, stages of sleep. Examples include eating, smoking and drinking caffeine and urination |
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Ultradian example: sleep cycle |
Psychologists have identified 5 distinct stages that altogether span approx 90 mins A cycle that continues throughout the course of the night. Each stage is characterised by a different level of brainwave activity which can be monitored using an EEG During a typical night a sleeper passes through the cycle between 5-7 times |
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The sleep cycle- stages 1 and 2 |
Lowered heart and muscle tension Brainwaves are slowing down. Light sleep |
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The sleep cycle- stages 3 and 4 |
Deeper sleep characterised by slower waves and sleep spindles Difficult to wake Disorientated if woken but brain will respond to significant noises |
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The sleep cycle- stage 5 |
The sleep goes back up 'sleep staircase' to stage 2 and there's a period of REM (rapid eye movement) sleep lasting for about 15-20 mins Here is where the body is paralysed but brain activity speeds up in a manner that resembles the awake brain Research has suggested that REM activity during sleep is highly correlated with the experience of dreaming. |
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Evidence supports the idea of distinct stages in sleep |
Dement and kleitman Monitored the sleep patterns of 9 adult participants in a sleep lab Brainwave activity was recorded on an EEG and the researchers controlled the effects of caffeine and alcohol REM activity during sleep was highly corrleated with the experience of dreaming Brain activity varies according to how vivid dreams were and participants woken during dreaming reported very accurate recall of there dreams. Replications of this investigation has noted similar findings though small sample size of the original sample has been criticised His study uses objective methods and the variables are controlled as they are able to control location, sleeping time and use of stimulants Lab study= lacks ecological validity= affected their sleep pattern. So therefore, the study suggests that REM sleep is an important component of the ultradian sleep cycle. |
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Existence of the basic rest activity cycle |
Kleitman Suggested that a similar 90 minute rhythm cycle continues during waking hours It's characterised by a period of alertness followed by a spell of psychological fatigue Anecdotal evidence supports the evidence BRAC such as the frequent observation that students find it difficult to concentrate for periods longer than 90 mins at a time Ericsson et al found that the best performed tended to practise for 3 sessions during the course of the day, each session lasts no more than 90 mins and there was a break between each in order to recharge |
