How is the nervous system divided?
Into 2 halves - Central nervous system & Peripheral nervous system
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How is the central nervous system divided?
Spinal cord & Brain
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What is the central nervous system?
Has two main functions: the control of behaviour and to regulate the body's physiological processes
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How does the CNS carry out its two functions?
By the brain being able to receive information from sensory receptors which sends messages to muscles and glands of the body. This also involves the spinal cord
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What is the spinal cords function?
To relay information between the brain and rest of the body. This allows the brain to monitor & regulate bodily processes such as digestion & breathing and to coordinate voluntary movements
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What is the spinal cord connected to?
Different parts of the body by pairs of spinal nerves, which connect with specific muscles and glands. E.g. spinal nerves which branch off from thoracic region of spinal cord carry messages to/from chest and abdomen
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What does the spinal cord contain?
Circuit of nerve cells that enable us to perform some simple reflexes without the direct involvement of the brain e.g. pulling your hand away from something that it hot
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What are the four areas that the brain can be divided into?
The cerebrum, cerebellum, diencephalon and brain stem
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What is the cerebrum?
Largest part of brain & further divided into four lobes, each of which has different primary functions e.g. frontal lobe is involved in thought and production of speech. Is split down middle into 2 halves called cerebral hemispheres
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How do cerebral hemispheres communicate?
Through the corpus callous
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What is the cerebellum?
Sits beneath the back of cerebrum and is involved in controlling a person's motor skills & balance, coordinating the muscles to allow precise movements
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What is diencephalon?
Lies beneath the cerebrum & top of brain stem. Within this area there are 2 important structures: thalamus (relay station for nerve impulses) and hypothalamus (regulation of body temp/ hunger)
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What is the brain stem?
Is responsible for regulating automatic functions essential for life e.g. breathing, heartbeat, swallowing. Motor & sensory neurons travel through brain stem, allowing impulses to pass between brain/spinal cord
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What is the peripheral nervous system?
All nerves outside CNS make up PNS. Function is to relay impulses from CNS to rest of the body & from body back to CNS
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What is the somatic nervous system?
Made up of 12 pairs of cranial nerves & 31 pairs of spinal nerves. These nerves have both sensory (relay messages to CNS) /motor neurons (relay information from CNS to rest of body). Involved in reflex actions without involvement of CNS
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What is the autonomic nervous system?
Are involuntary actions such as heart beating, they are necessary as vital bodily functions wouldn't work so efficiently if you had to think about them
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What is sympathetic nervous system?
Primarily involved in responses that help us deal with emergencies such as increasing heart rate etc. Neurons from SNS travel to virtually every organ & gland within body, preparing body for rapid action necessary if under threat
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What is parasympathetic nervous system?
Relaxes an individual once emergency has passed. Where SNS causes heart to beat faster, the PSN slows heartbeat down. Digestion also begins under PNS influence as involved with energy conservation - referred to as body's rest & digest system
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What are neurons?
Are cells that are specialised to carry neural information throughout the body. Dendrites at one end receive signals from other neurons/ sensory receptors. Connected to cell body, control centre of neuron.
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What happens from the cell body of a neuron?
The impulse is carried along the axon, where it terminates the axon terminal
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In many nerves there is an insulating layer that forms around the axon what is this?
The myelin sheath which allows nerve impulses to move more rapidly along axon & if damaged, impulses slow down
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What are sensory neurons?
Carry nerve impulses from sensory receptors to spinal cord/brain. Found in various locations of body e.g. eyes, ears etc. Convert information from sensory receptors into neural impulses which when reach brain are translated into sensations
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What are relay neurons?
Lie somewhere between sensory input and motor output. They allow sensory/motor neurons to communicate with each other and lie within brain and spinal cord
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What are motor neurons?
Refer to neurons located in CNS that project their axons outside the CNS and directly/indirectly control muscles. Form synapses with muscles & control their contractions.
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What happens to motor cortex when stimulated?
Motor neurons releases neurotransmitters that bind receptors on muscle & trigger a response which leads to muscle movement
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What happens when an action potential arrives at terminal button at end of axon?
It needs to be transferred to another neuron/tissue - it must cross a gap between presynaptic neuron & postsynaptic neuron
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What is the physical gap between pro- and post-synaptic cell membranes known as?
The synaptic gap & end of axons of nerve cell are number of sacs known as synaptic vesicles which contain chemical messengers that assist in transfer of impulse
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What happens when action potential reaches synaptic vesicles?
Causes them to release their contents through process of exocytosis
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What does the released neurotransmitter do?
Diffuse across the gap between pre- and post-synaptic cells, where it binds to specialised receptors on surface of cell. Once activate, receptor molecules produce either excitatory/inhibitory effects on post-synaptic neuron
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When then happens to neurotransmitter?
It is taken up again by pre-synaptic neuron, where it is stored and made available for later release
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What are excitatory neurotransmitters?
Such as noradrenaline are nervous systems 'on switches' & increase likelihood that an excitatory signal is sent to post-synaptic cell which is then more likely to fire at a higher rate
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What are inhibitory neurotransmitters?
Such as serotonin & GABA are nervous systems 'off switches' in that they decrease the likelihood of that neuron firing & they are generally responsible for calming the mind/body.
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Inhibitory neurotransmitter binding with post-synaptic receptor result in?
An inhibitory post-synaptic potential, making it less likely the cell will fire if at all
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What is the endocrine system?
Is a network of glands throughout the body that manufacture and secrete chemical messengers known as hormones. Uses blood vessels to deliver hormones to target sites in body
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What are the major glands?
Pituitary, adrenal and reproductive organs. Each gland in endocrine system produces different hormones, which regulate activity of organs & tissues in body
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How is endocrine system regulated?
By feedback e.g. signal is sent from hypothalamus to pituitary gland in form of releasing hormone which causes pituitary to secrete stimulating hormone into bloodstream which signals target gland
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What happens as levels of hormone rise in the bloodstream?
The hypothalamus shuts down secretion of releasing hormone & pituitary gland shuts down secretion of secreting hormone which results in stable concentrations of hormones circulating in bloodstream
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What are hormones?
Are chemicals that circulate in bloodstream & carried to target sites through body. Although hormones come into contact with most cells in body, a given hormone usually affects only a limited number of cells which respond to particular hormone
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What happens when enough receptor sites are stimulated by hormones?
Results in a physiological reaction in target cell. Timing of hormone release is critical for normal functioning, as are levels of hormones released
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What is pituitary glands primary function?
To influence release of hormones from other glands and regulate many of body functions. It is controlled by hypothalamus, a region of brain above pituitary gland
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Where does hypothalamus receive information from?
Many sources about basic functions of body and uses this information to regulate these functions.
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As the master gland what does the pituitary do?
Produce hormones that travel in bloodstream to their specific target which either directly cause changes in physiological processes of body or stimulate other glands to produce other hormones
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What are the two parts of pituitary gland?
Anterior pituitary & posterior pituitary both have different hormones which target different parts of the body and produce a number of different hormones
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What hormone does anterior pituitary release?
ACTH as a response to stress which stimulates the adrenal glands to produce cortisol
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What hormone does posterior pituitary release?
Releases oxytocin, which stimulates contraction of uterus during childbirth
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What are adrenal glands?
Two adrenal glands sit on top of kidneys and each is made up on two parts: outer - adrenal cortex & inner - arena medulla. Each with different functions
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Outline adrenal cortex
Produces cortisol, which regulates a variety of important bodily functions including cardiovascular & anti-inflammatory functions. Cortisol production increases in response to stress & if cortisol level is low, the individual has low blood pressure
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Outline adrenal medulla
Releases adrenaline/ noradrenaline which prepare body for fight or fight response. Adrenaline helps body respond to stressful situations & noradrenaline constricts blood vessels, causing blood pressure to increase
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Outline the ovaries as reproductive systems
Are par of female reproductive system & responsible for production of eggs & hormones oestrogen and progesterone (more important in post-ovulation phase of menstrual cycle)
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What else has progesterone been associated with?
Heightened sensitivity to social cues that indicate presence of social opportunity or threat that would be significant in case of pregnancy
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Outline the testes as reproductive systems
Are male reproductive glands that produce hormone testosterone which causes development of male characteristics. Testosterone production is controlled by hypothalamus and pituitary gland
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When is the amygdala in the brain mobilised?
When an individual is faced with a threat and it is associated with sensory signals & emotions associated wth fight or flight
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What does the amygdala do in fight or flight response?
Sends a distress signal to hypthothalamus which communicates with rest of body through sympathetic nervous system. Body's response to ongoing stressors involves 2 major systems: 1 = sudden stress, 2= ongoing stress
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What is the the response to acute stressors called?
The pituitary adrenaline system - HPAC
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Outline HPAC
Hypothalamus is in charge of stress response & when triggered releases a chemical message. Pituitary controls glands of endocrine system & when activated releases hormone ACTH which through bloodstream activates adrenal cortex
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What does adrenal cortex release?
Hormones called corticosteroids which have several functions including releasing stored glucose & controlling swelling after an injury
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What is the response to chronic stressors called?
The sympathomedullary pathway - HANSAM
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Outline HANSAM
When stress response is triggered hypothalamus sends signals to brainstem which triggers sympathetic branch of sympathetic nervous system which via nerves activates adrenal medulla
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What does adrenal medulla release?
Hormones called adrenaline/noradrenaline. These hormones get body ready for fight or flight response & create changes in body such as increased blood pressure
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Where is primary visual centre in brain located?
In visual cortex, in occipital lobe of brain but processing actually begins in the retina at back of eye, where light enters & strikes the photoreceptors
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Outline visual processing
Nerve impulses from retina are transmitted to brain via optic nerve.
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Explain hemispheres and inputs according to visual centres
Right hemisphere receives input from left-hand side of visual field, while visual cortex in left hemisphere receives input from right-hand side of visual field
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What is auditory centre of brain concerned with?
Hearing and most of this area lies within temporal lobes on both sides of brain where we find auditory cortex
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Where to auditory pathways begin?
In the cochlea in the inner ear, where sound waves are converted to nerve impulses which travel via auditory nerve to auditory cortex in brain
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What is the process of auditory pathways?
1) within brainstem a basic decoding takes place, 2)the thalamus acts as a relay station and carries out further processing of auditory stimulus 3)auditory cortex which recognises an appropriate response
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What is motor cortex responsible for?
The generation of voluntary motor movements and is located in frontal lobe of brain, along bumpy region known as precentral gyrus
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Do both hemispheres of the brain have a motor cortex?
Yes with motor cortex on one side of brain controlling muscles on opposite side of body
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What does the somatosensory cortex detect?
Sensory events arising from different regions of body and is located in parietal lobe of brain
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How does somatosensory cortex produce sensations of touch, pressure, paid & temperature?
Using sensory information from skin and it localises to specific body regions
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Do both hemispheres of the brain have a somatosensory cortex?
Yes with the cortex on one side of the brain receiving sensory information from opposite side of body
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Who is Broca's area named after?
Paul Broca, the French neurosurgeon who treated a patient who he referred to as Tan as that was the only syllable this particular patient could express
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What was Tan's usual disorder?
He had been able to understand spoken language and unable to speak or express his thoughts in his writing
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What did Broca find among his 8 patients?
They all had similar language deficits, along with lesions in their left frontal hemispheres. Patients with damaged to these areas in right hemisphere don't have same language problems
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What did Broca's findings lead to?
The identification of existence of language centre in posterior portion of frontal lobe of left hemisphere
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What did Wernicke, a German neurologist discover?
Another area of brain involves in understanding langue that was in posterior proportion of left temporal lobe. Patients with lesion in this area could speak but unable to understand language
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What does hemispheric lateralisation refer to?
The fact that two halves of brain are not exactly alike as each hemisphere has functional specialisations e.g. language is localised primarily in 1/2 of brain
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What has research found in relation to hemispheric lateralisation?
That the left-hemisphere is dominant for language & speech whereas right is visual-motor tasks
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How can information be sent from one hemisphere to another?
Through connecting bundles of nerve fibres such as corpus callous
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Who were the first people to study the capabilities of split-brain research?
Sperry & Gazzaniga
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How did they test the capabilities of separated hemispheres?
They were able to send visual information to just one hemisphere at a time in order to study the hemispheric lateralisation
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Outline the typical study?
The split-brain patient would fixate on a dot in centre of screen while information was presented either left/right of visual field. Would then be asked to make responses with left/right hand without being able to see what their hands were doing
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What occurs with information from left visual field?
Is processed by right hemisphere, which can see the picture but has no language centre so patient cannot respond verbally
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What occurs with information from right visual field?
Is processed by left hemisphere which does not have a language centre but does not receive information about seeing the picture and so patient cannot say they've seen it
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What does brain plasticity refer to?
The brains ability to change & adapt as a result of experience and this ability to change plays important role in brain development & behaviour.
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What did researchers use to believe about brain plasticity?
That changes in the brain only took place during infancy & childhood but more recent has demonstrated that the brain continues to create new neural pathways
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Outline playing video games as an example of plasticity
Been found that they make different complex cognitive & motor demands. Kuhn et al compared control group with video game training group that was trained for 2 months for at least 30 minutes a day on same Super Mario
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What did Kuhn et al find?
An increase grey matter in various brain areas such as hippocampus and cerebellum & this increase was not evident in control group that didn't play the game
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What did the researchers conclude?
That video game training had resulted in a new strategic planning, working memory and motor performance
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Outline what researchers found when working with Tibetan monks in regards to plasticity
Davidson et al compared 8 practitioners of Tibetan meditation with 10 student volunteers with no previous meditation experience. Both groups fitted with electrical sensors & asked to meditate for short periods
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What did the electrodes find?
Picked up greater activation in gamma wave activity in monks whereas students showed only slight increase while meditating
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What did the researchers conclude?
That mediation not only changes workings of brain in short term but may also produce permanent changes
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What did research in 1960s find about functional recovery after trauma?
That stroke victims were able to regain functioning & they discovered that when brain cells are damaged/destroyed the brain re-wires itself over time so some level of functioning can be regained. Neurons next to damaged ones form new circuits
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Outline stem cells as functional recovery after trauma
Stem cells are unspecialised cells that have potential to give rise to different cell types that carry out different functions, including taking on characteristics of nerve cells
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What views are there regarding stem cells?
1)Stem cells implants into brain would directly replace dead or dying cells 2)Transplanted stem cells secrete growth factors that somehow rescue the injured cells
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What are post-mortem examinations?
Are used to establish the underlying neurobiology of particular behaviour. When person dies a researcher can examine their brain to look for abnormalities that might explain for certain behaviours
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What are functional magnetic resonance imaging?
Technique for measuring changes in brain activity while person performs a task. Does this by measuring changes in blood flow in particular areas on brain which indicates increased neural activity.
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What happens if a particular area of the brain becomes more active?
There is an increase for oxygen in that area & brain responds to this extra demand by increasing blood flow, delivering oxygen in red blood cells. As a result, researchers can produce maps showing which areas of brain are involved in mental acitivity
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What are electroencephalogram's?
Measure electrical activity in brain by placed electrodes on scalp to detect small electrical charges which result from activity of brain cells. Electrical signals from electrodes are graphed over period of time which result in representation = EEG
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How can EEG data be used?
To detect various types of brain disorders such as epilepsy or to diagnose other disorders that influence brain activity such as Alzheimer's disease
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What are event-related potentials?
Small voltage charges in brain are triggered by significant events/stimuli such as cognitive processing of a stimulus. ERPs difficult to pick out from other electrical activity being generated within brain.
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How are specific responses to target stimulus gathered?
They require presentations of stimulus & these responses are then averaged together
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What is a circadian rhythm?
Is a pattern of behaviour that occur/recurs approximately every 24hrs and is set/reset by environmental light levels
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What are our circadian rhythms driven by?
Our body clocks which are found in all cells of the body & synchronised by master circadian pacemaker, the suprachiasmatic nuclei
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What does light provide?
The primary input to this system, setting body clock to correct time through a process called photo entrainment. In light mammals, light-sensitive cells within eye act as brightness detectors, sending messages about environmental light levels to SCN
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What is the sleep-wake cycle?
Refers to alternating states of sleep/waking that are dependent on 24hr circadian cycle. Light & darkness are external signals which determine when we feel need to sleep & when to wake up
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When does circadian rhythm dip and rise during the day?
Strongest sleep usually occurs in two dips between 2-4am & 1-3pm. Sleepiness we experience during these circadian dips is less intense if we have had sufficient sleep & more intense when we are sleep deprived
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When is body temperature at its lowest & highest?
Lowest = 4:30am & Highest = 6pm
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During a normal circadian rhythm when does sleep occur?
When core temperature begins to drop & body temperature begins to rise during last hours of sleep, promoting feeling of alertness in the morning
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Discuss hormone production in relation to circadian rhythms
Produce & release of melatonin from pineal gland in brain follows this with peak levels occurring during the hours of darkness
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By activating chemical receptors in the brain what does melatonin encourage?
Feelings of sleep and when its dark, more melatonin is produced & when its light produce of melatonin drops and person wakes
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Who completed a study on circadian rhythms?
French cave explorer Siffre who subjected himself to long periods of time living underground in order to study his own circadian rhythms
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What was the environment like underground?
No external cues to guide his rhythms, simply woke, ate & slept when he felt it appropriate to do so. Only thing influencing his behaviour was internal body clock
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How long was the first underground stay and what happened to Siffres circadian rhythms?
61 days in Southern Alps in 1962 - when he resurfaced on 17th Sep he believed it to be Aug 20th
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How long was the second underground stay and what happened to Siffres circadian rhythms?
6 months in a cave in Texas, his natural circadian rhythm settled down to just over 24hrs
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What is an ultradian rhythm?
In humans, daily cycles of wakefulness & sleep follow a circadian rhythm however, within sleep proportion of this cycle ultradian rhythms take over - anything shorter than 24hrs
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What pattern does the ultradian rhythm found in human sleep follow?
Pattern of alternating REM which consists of stages. This cycle repeats itself around every 90 minutes throughout the night
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What occurs as a person enters deep sleep?
Their brainwaves slow & breathing and heart rate decrease
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What is first stage of sleep?
Light sleep, muscle activity slows down & occasional muscle twitching
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What is second stage of sleep?
Breathing pattern & heart rate slows & slight decrease in body temperature
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What is third stage of sleep?
Deep sleep begins, brain begins to generate slow delta waves
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What is fourth stage of sleep?
Very deep sleep, rhythmic breathing & limited muscle activity
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What is the fifth stage of sleep?
Rapid eye movement, brainwaves sleep up & dreaming occurs
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What did Kleitman suggest in regards to BRAC?
That the 90 minute ultradian rhythm continues during the day even when we are awake
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Whats the difference between rhythm in day/night?
During day rather than moving through sleep stages, we move progressively from state of alterness into state of physiological fatigue
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What does research suggest in regards to BRAC?
That human mind can focus for period of around 90 minutes & towards end of this body begins to run out of resources, resulting in loss of concentration, fatigue & hunger
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What is an infradian rhythm?
Are rhythms that have a duration greater than 24hrs. They may be cycles lasting days, weeks, months or annual
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What would an example of weekly rhythms be?
That although male testosterone levels are elevated at weekends & young couples report more sexual activity at weekends the frequency of births at weekends is lower than weekdays
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What would an example of monthly rhythms be?
A woman's reproductive cycle - menstrual cycle - as it lasts around a month. There are considerable variations in lengths of this cycle, with some women experining short 23-day cycle whereas others 36-days. Average = 28days
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What is the menstrual cycle regulated by?
Hormones which either promote ovulation or stimulate uterus for fertilisation. Ovulation occurs roughly 1/2 way through cycle, when oestrogen levels peak.
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What happens after the ovulatory phase?
Progesterone levels increase in preparation for possible implantation of an embryo in uterus
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What would an example of annual rhythms be?
In most animals they are related to seasons but in humans the calendar year appears to influence behaviour regardless of changes in temperature
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What does research suggest about season variation?
Variation in mood in humans, especially in women with some people becoming severely depressed during winter months
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What is winter also associated with?
An increase in heart attacks - in fact, there is a strong annual rhythm in human deaths with most deaths occurring in January
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What is an endogenous pacemaker?
Are products of inherited genetic mechanisms & allow us to keep pace with changing cycles in environment
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In mammals what is the main endogenous pacemaker?
Is a tiny cluster of nerve cells called suprachiasmatic nucleus which lies in hypothalamus
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What role does SCN play?
Generates the body's circadian rhythm & acts as the master clock with links to other brain regions that control sleep & arousal and has control over other biological clocks throughout body
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What do neurons within SCN do?
They synchronise with each other so that their target neurons in sites elsewhere in body receive correctly time-coordinated signals
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What does the suprachiasmatic nucleus do in regards to the pineal gland?
Sends signals to pineal gland, directing it to increase production & secretion of hormone melatonin at night & to decrease it as light levels increase in the morning.
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What does melatonin do?
Induces sleep by inhibiting the brain mechanisms that promote wakefulness
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How does the pineal gland and SCN function jointly as an endogenous pacemaker?
Sensitivity of pineal gland & SCN to light and role of melatonin in controlling sleep & activity means that despite the endogenous nature of these clocks their activity must be synchronised with light-dark rhythms of outside world
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What are exogenous zeitgebers?
Refer to anything whose origins are outside the organism & responsible for entraining biological clock of organism
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How is light linked to exogenous zeitgebers?
Receptors in the suprachiasmatic nucleus are sensitive to changes in light levels during day & use this information to synchronise the activity of body's organs & glands. Light resets this internal clock each day, keeping it on 24hr cycle
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How is light detected?
Rods & cones in retina of eye detect light to form visual images
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What is the third type of light-detecting cells in retina that gauges overall brightness to help reset internal biological clock?
Protein called melanopsin which is sensitive to natural light is critical in this system & small number of retinal cells contain this and carry signals to SCN to set daily bodily clock
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What else may act as zeitgebers?
Social stimuli such as mealtimes & social activities
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What did Aschoff et al show?
That individuals are able to compensate for absence of zeitgebers such as natural light by responding to social zeitgebers instead
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What did one of the earliest studies on jet lag find?
Air travellers adjusted more quickly if they went outside more at their destination
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What is the spinal cords function?


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