Draw the nervous system ?
(The Nervous System)
What is the nervous system and what are its functions ?
(The Nervous System)
It is a specialised network of human cells
It is our primary internal communication system
Functions:
Collect, process and respond to information in the environment
Co-ordinate the working of different organs and cells within the body
What are the parts of the central nervous system and what do they do ?
(The Nervous System)
Brain:
Centre of all conscious awareness
The brains outer layer - cerebral cortex - highly developed for humans and distinguishes us from animals
Has two hemispheres
Spinal Cord:
Extension of the brain
Sends messgaes to and from the brain
Connects nerves to PNS
Responsible for reflex actions
What is the rold of the peripheral nervous system ?
(The Nervous System)
Transmits messages via neurons to and from the CNS
Sends information to the CNS from outside world
Transmits messages from CNS to rest of the body
What does the autonomus and semantic nervous system do ?
(The Nervous System)
Part of the peripheral nervous system
Autonomic:
Controls vital body functions
Transmits information to and from bodily organs
System is operated involuntarily
Somantic:
Controls muscle movements
Recieves information from sensory receptors and transfers to CNS
Receives information from CNS which directs muscles to act
What do the sympathetic and parasympathetic nervous system do ?
(The Nervous System)
Pat of autonomic nervous system
Sympathetic:
Has a stimulating effect on the body
Involved in responses that help us deal with emergencies
Parasympathetic:
Relaxes individual after threat has passed
Slows down heart rate, blood pressure and breathing
Name some of the biological changes involved with sympathetic and parasympathetic response ?
(The Nervous System)
Name the major endocrine glands ?
(The Endocrine System)
What is the role of the endocrine system ?
(The Endocrine System)
It is responsible for instructing glands to release hormones directly into the bloodstream (each gland produces a different hormone)
Hormone affect any cell in the body that has a receptor for that particular hormone
What is the key endocrine gland ?
(The Endocrine System)
Gland - organ in the body that produces hormones
Key endocrine gland = Pituity gland
It controls the release of hormones from all other glands
What is the Pineal gland responsbile for ?
(The Endocrine System)
Receives information about light and dark cycle from the environment
Produces and secretes melatonin
What is the thyroid gland responsible for ?
(The Endocrine System)
Produces hormone ‘thyroxine’
Hormone affects heart cells (increasing heart rate)
Also affects cells throughout the body (increasing metabolic rate)
What are the two parts of the adrenal gland and what are they responsible for ?
(The Endocrine System)
Adrenal Cortex (Outer Layer):
Releases cortisol when stressed - increases sugars in the bloodstream
Adrenal Medulla (Inner):
Releases adrenaline - Increases blood pressure and heart rate
What do the ovaries and testes produce ?
(The Endocrine System)
Ovaries:
Produce oestrogen - regulates ovulation
Produce progesterone - involved in post ovulation
Testes:
Produce testosterone - causes development of male characteristics
Also plays role in sex drive, sperm production and male strength
What is fight or flight ?
(Fight or flight)
An evolved survival mechanism - allows humans to act quickly in life threatening situations
What is step 1 of fight or flight ?
(Fight or flight)
When a stressor is perceived -> hypothalamus triggers sympathetic nervous system
What is step 2 of fight or flight ?
(Fight or flight)
Autonomic nervous system shifts from resting state
Sympathetic nervous system triggered - prepares body for rapid action necessary for fight or flight
SNS sends message to adrenal medulla -> releases adrenaline into bloodstream
What is step 3 of fight or flight ?
(Fight or flight)
Adrenaline triggers changes in the body:
Increased heart rate
Breathing becomes more rapid
Release of blood sugar and fat in to bloodstream
Dilated pupils
Inhibition of less important functions
What is step 4 of fight or flight ?
(Fight or flight)
Once threat has passed parasympathetic nervous system returns
All functions effected during process return back to normal
Freeze response - Hypervigilent assesment situation
Evaluation - Limitation - Doesnt account for freezing
(Fight or flight)
Point - Does not account for the freeze repsonse that occurs before fight or flight.
Explain - Gray claims the first response to danger is to avoid it altogether. The freeze response is when humans become hypervigilent while asessing a situation to decide on the best course of action
Androcentric - Woman protect offspring
Evaluation - Limitation - May be gender differences
(Fight or flight)
Point - Not everyone goes through fight or flight response. Early research was typically conducted on males and is therefore androcentric.
Further - Taylor et al, investigated fight or flight responses and found that women are more likely to protect there offspring and form other alliances with women than fight or flee
Evolution of F & F - Stress modern day life
Evaluation - Limitation - Negative effects on mental health in everyday life
(Fight or flight)
Point - Fight or flight may not have adapted to modern life meaning it could have a damaging effect on health. Fight or flight was a useful mechanism for our ancestors but modern day life rarely requires such an intense biological response.
Further - The stressors of modern day life can repeatedly activate the response which can have negative consequences on our health. Continuous stress increases blood pressure which can damage heart and blood vessels.
What is a neuron and what does it do ?
(Synaptic Transmission)
Neurons are nerve cells
They transmit signals electrically and chemically
They provide the nervous system with its primary means of communication
What makes up the structure of a neuron ?
(Synaptic Transmission)
Neurons can range from less than 1mm to 1m long
Cell body - Contains nucleas and genetic material of the cell
Dendrites - Branch like structures which protrude from the cell. Carry nerve impulses from neighbouring cells towards the cell body
Axon - Carries impulses away from the cell body
Myelin Sheath - Fatty layer which covers and protects the axon and speeds up the electrical transmission of an impulse
Nodes of Ranvier - Gaps between segments of the myelin sheath. Speeds up transmission of the impulse by forcing it to jump across the gaps along the axon
Terminal Buttons - at the end of the axon. Communicates with the next neuron
Coke Does Activate Many Naughty Thoughts
Draw the structure of a basic neuron ?
(Synaptic Transmission)
Whats the function and structure of a sensory neuron ?
(Synaptic Transmission)
Function - Carry messages from the sensory receptors in PNS to the CNS
Structure:
Long dendrites and short axons
Located in the PNS in clusters called ganglias
Whats the function and structure of a relay neuron ?
(Synaptic Transmission)
Function - connect sensory neurones to motor or other relay neurons
Structure:
short dendrites and short axons, they have no myelin sheath
Only found in the CNS
Whats the function and structure of a motor neuron ?
(Synaptic Transmission)
Function - Connects the CNS to effectors like muscles and glands
Structure:
Short dendrites and long axons
Located in the CNS but long axons form part of PNS
What is electrical transmission ?
(Synaptic Transmission)
When a neuron is in resting state the inside of the cell is negatively charged compared to the outside.
When a neuron is activated the inside of the cell becomes postivaly charged for a split second causing and action potential to occur.
This creates an electrical impulse that travels down the neuron towards the end of the axon.
What is synaptic transmission ?
(Synaptic Transmission)
Signals within neurons are transmitted electrically - signals between neurons are transmitted chemically = synaptic transmission
Draw the process of synaptic transmission ?
(Synaptic Transmission)
Explain the process of synaptic transmission ?
(Synaptic Transmission)
Neurotransmitters are chemicals that diffuse across the synapse to the next neuron
Once it crosses the gao it is taken up in the postsynaptic recpetor site
The chemical is converted back to a electical impulse
Each neurotransmitter has its own specific molecular structure that fits perfectly into the postsynaptic receptor site
They also have specialist functions - acetlylcholine causes muscles to contract
What is the definition of excitation and inhibition ?
(Synaptic Transmission)
Excitation - When a neurotransmitter increases the positive charge of the postsynaptic neuron. Increasing the likelihood that the neuron will fire and pass on the electrical impulse.
Inhibition - When a neurotransmitter makes the charge of a postsynaptic neuron more negative. Decreasing the likelihood the neuron will fire and pass on the electrical impulse.
For a postsynaptic nerve to fire it is decided by the process of summation
What is the difference between right and left hemisphere of the brain ?
(Localisation and Function of the Brain)
Symmetrical halves of the brain
Left hand side of body controlled by right hemisphere
Right hand side of body controlled by left hemisphere
What is the cerebral cortex ?
(Localisation and Function of the Brain)
Outer layer of both hemispheres - Humans have a more developed cerebral cortex to animals
What are the functions of different lobes in the brain and where are they found ?
(Localisation and Function of the Brain)
Frontal lobe - Voluntary movement, reasoning, mood, personality, impulse control
Occipital lobe - Visual processing centre
Temporal lobe - Processing auditory stimuli
Parietal lobe - Processing the sense of touch, limb position, and spatial awareness
What are the 6 areas of the brain and where are they located ?
(Localisation and Function of the Brain)
M W
B
S
A V
What does the motor cortex do ?
(Localisation and Function of the Brain)
Location – back of the frontal lobe in both hemispheres
Function – controls voluntary movement in the opposite side of the body
Damage may result in loss of control over movements
What does the somatosensory cortex do ?
(Localisation and Function of the Brain)
Location – front of parietal lobes in both hemispheres
Function – sensory information from the skin is represented
Damage – decreased ability to differentiate/feel stimuli
What does the visual cortex do ?
(Localisation and Function of the Brain)
Location – occipital lobe at the back of brain in both hemispheres
Function –eye sends information:
Images from the right visual field sent to the left visual cortex
Images from the left visual field sent to the right visual cortex
Damage to:
Left hemisphere can produce blindness in part of the right visual field of both eyes
Right hemisphere can produce blindness in part of the left visual field of both eyes
What does the auditory cortex do ?
(Localisation and Function of the Brain)
Location – temporal lobes in both hemispheres
Function – analyses speech-based information
Damage - may produce partial hearing loss – the more extensive the damage the more extensive the loss
What does the Broca’s area do ?
(Localisation and Function of the Brain)
Identified by Paul Broca in 1880S
Location - a small area in the left frontal lobe
Function - responsible for speech production
Damage – causes Broca’s aphasia – speech which is slow, laborious and lacking in fluency
What does the Wernicke’s area do ?
(Localisation and Function of the Brain)
Identified by Karl Wernicke in 1880s
Location – left temporal lobe
Function – responsible for language comprehension
Damage – causes Wernicke’s aphasia – produce nonsense words as part of speech #
Wernicke’s and Broca’s brain scans -
Evaluation - Strength – Research Support from Brain Scan Evidence ?
(Localisation and Function of the Brain)
Point - Peterson et al – used brain scans to demonstrate how Wernicke’s area was active during a listening scan and Broca’s area was active during a reading task
Further – Tulving et al – studied long-term memory – found that semantic and episodic memories reside in different parts of prefrontal cortex
Wernicke’s and Broca’s brain scans -
Evaluation - Strength – Research Support from Brain Scan Evidence ?
(Localisation and Function of the Brain)
Point - Peterson et al – used brain scans to demonstrate how Wernicke’s area was active during a listening scan and Broca’s area was active during a reading task
Further – Tulving et al – studied long-term memory – found that semantic and episodic memories reside in different parts of prefrontal cortex
Brain reorganises when damaged - learning is distributed holistically
Evaluation - Limitation – Contradictory Research ?
(Localisation and Function of the Brain)
Point - Lashley – Plasticity – when the brain has become damaged through illness or accident, and a particular function is compromised or lost, the rest of the brain appears to reorganise itself in an attempt to recover the lost function
Further – Lashley – work also suggests that higher cognitive functions, such as processes involved in learning, are not localised but distributed in a more holistic way in the brain
Evaluation - Strength – Research Support for Language Centres ?
(Localisation and Function of the Brain)
Point - Aphasia studies show that damage to Broca’s and Wernicke’s areas results in different types of aphasia showing that they have different functions.
Counter – language production may not be confined to Broca’s area – Dronkers et al – examined preserved brains of two of Broca’s patients using MRI imaging – revealed that other areas besides Broca’s area could have contributed to speech difficulties
What is hemispheric lateralisation ?
(Hemispheric Lateralisation and Split Brain Research)
The idea that the 2 hemispheres of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by 1 hemisphere rather than the other
Left hemisphere – dominant for language and speech
Right hemisphere – dominant for visual-motor tasks
The 2 hemispheres are connected by a bundle of nerves – corpus callosum - allows for transfer of information between hemispheres
What is the background and aim of Sperry and Gazaniga’s study ?
(Hemispheric Lateralisation and Split Brain Research)
Background - all participants had undergone surgery to reduce epileptic seizures - corpus callosum being cut down the middle to separate the 2 hemispheres
means information presented to one hemisphere has no way of travelling to the other hemisphere
Aim – to investigate the extent to which the 2 hemispheres are specialised for certain functions and whether the hemispheres perform tasks independently of the other
What was the procedure of Sperry and Gazaniga’s study ?
(Hemispheric Lateralisation and Split Brain Research)
Ps asked to focus on a dot (fixation point) on the centre of a screen.
Images/words projected to the Ps’ right visual field (Left Hemisphere) and some to the left visual field (Right Hemisphere)
3 tests were:
Can they describe what they see? (can they say the words they see)?
Can they touch an object which matches what they have seen on the board?
Can they draw what they see?
What were the findings of Sperry and Gazzaniga’s study ?
(Hemispheric Lateralisation and Split Brain Research)
Describing what they could see - When picture shown to Ps’ right visual field (LH), P could easily describe what was seen but left could not
Recognition by touch - Objects shown in left visual field (RH) Ps were able to select a matching object from a grab bag using their left hand (RH)
Drawing Activity - The left hemisphere is not dominant for drawing, if an image was flashed to the right visual field (LH) and they try to draw with right hand (LH), they couldn’t
Matching Faces - When completing a face matching task, Ps selected faces shown to left visual field (RH), whilst images presented to right visual field (LH) were ignored
What were the conclusions of Sperry and Gazzaniga’s study ?
(Hemispheric Lateralisation and Split Brain Research)
Left hemisphere – responsible for speech and language
Right hemisphere – responsible for visual motor tasks and face recognition
Cannot cheat 1/10th second - Participants history influence results
Evaluation - Strength – Methodology used Highly Standardised Procedures ?
(Hemispheric Lateralisation and Split Brain Research)
Point - Sperry’s method of using the fixation point and the fact that the image/word was only flashed up for 1/10th of a second meant Ps could not have time to move their eye across the image and spread the information across both visual fields and both hemispheres which ensured that information was only being received by 1 hemisphere at a time
Counter – the sample used was very unusual – only 11 Ps and all had a history of epileptic seizures which may have caused unique changes to their brains and may have influenced results
JW left hemisphere damaged - Idiographic
Evaluation - Limitation – Language may not be Restricted to the Left Hemisphere ?
(Hemispheric Lateralisation and Split Brain Research)
Point - Turk et al - Case study of a patient JW evidence that the right hemisphere has the ability to process and produce speech – JW who suffered damage to left hemisphere developed the ability to speak from his right hemisphere
I&D– as this is a case study focusing on just one P, it takes an idiographic approach , focusing on an individual case in order to understand behaviour, which means meaningful generalisations can not be made
Evaluation - Strength – Philosophical Ideas of 2 Minds ?
(Hemispheric Lateralisation and Split Brain Research)
Point - Sperry’s work has prompted a philosophical debate about the nature of consciousness – Pucetti suggests that the 2 hemispheres are so functionally different that they represent a duality in the brain – we are 2 minds
Counter – other researchers argue that the 2 hemispheres do not work in isolation and instead form a highly integrated system which are both involved in everyday tasks
What is brain plasticity ?
(Plasticity and Functional Recovery)
Plasticity – the brain’s tendency to change and adapt as a result of experience and new learning
During infancy – brain experiences rapid growth in the number of synaptic connections it has
As we age, rarely used connexions are deleted and frequently used connections are strengthened – synaptic pruning
at any time in life existing neural connections can change or new neural connections can be formed
How does functional recovery occur after trauma ?
(Plasticity and Functional Recovery)
After trauma to the brain unaffected areas of the brain are able to adapt and compensate for the damaged areas
The brain rewires itself so that some level of function is regained
Healthy brain areas take over functions
Process can occur quickly after trauma – spontaneous recovery – and then slow down after several weeks or months
What is neural unmasking ?
(Plasticity and Functional Recovery)
Dormant synapses - usually ineffective as the neural input is too low for them to be activated
Unmasking - After surrounding brain area damaged there is increased rate of input to these synapses.
This opens up connections to regions of the brain that are not usually activated
What structural changes occur in the brain during functional recovery ?
(Plasticity and Functional Recovery)
A number of structural changes occur in the brain:
Axonal Sprouting – growth of new nerve endings which connect with other undamaged cells to form new neural pathways
Reformation of blood vessels
Recruitment of homologous (similar) areas on the opposite side of the brain to perform specific tasks
Evaluation - Strength – Research Support into Plasticity ?
(Plasticity and Functional Recovery)
Point - Maguire et al – found that posterior hippocampal volume of London taxi drivers’ brains positively correlated with their time as a taxi driver and that there were significant differences between taxi drivers’ brains and those of controls
Further - Kuhn et al - found a significant increase in grey matter in various regions of the brain after Ps played video games 30 minutes a day over a 2 month period compared to a control group
Evaluation - Limitation – Individual Differences in Functional Recovery ?
(Plasticity and Functional Recovery)
Point - Elbert et al - Functional recovery tends to reduce with age as the brain has a greater propensity for reorganisation in childhood as it is constantly adapting to new experiences and learning
Further – the number of years spent in education also has an impact – Schneider et al - the more time brain injury patients had spent in education, which gives an indication of their “cognitive reserve”, the greater their chances of a disability-free recovery
Evaluation - Strength – Real-Life Application to Neurorehabilitation ?
(Plasticity and Functional Recovery)
Point - Understanding the process of plasticity and functional recovery has led to the development of neurorehabilitation which uses motor and electrical stimulation of the brain to counter the negative effects and deficits in motor and cognitive functions following trauma/injury
Counter – this may also show the limitations of functional recovery as it highlights that although the brain has the capacity to “fix itself” to a point, this process requires further intervention to be completely successful
How does Functional Magnetic resonance imaging (FMRI) work ?
(Ways of investigating the Brain)
Measures changes in brain activity while a person performs a task
Detects changes in the blood oxygenation and flow that indicates increased brain activity
When bran area more active, it consumes more oxygen.
To meet the increased demand blood flow is directed to the active area
Produces 3D images (activation maps) showing which parts of the brain are involved
How does Electroencephalogram (EEG) work ?
(Ways of investigating the Brain)
Measures electrical activity within the brain
Electrodes that are fixed to an individual’s scalp using a skull cap – detects small electrical charges resulting from activity of brain dells
Signals from the different electrodes are graphed over a period of time
Provides an overall account of brain activity
Can detect various types of brain disorder or diagnose other disorders that influence brain activity
How does Event Related Potentials (ERPs) work ?
(Ways of investigating the Brain)
ERPs are very small voltage changes in the brain that are triggered by specific events or stimuli
Stimulus presented to P. Researcher looks for brain activity related to stimulus
Stimulus presented many times and an average response is graphed
Shows the neural responses associated with specific sensory, cognitive and motor events
What is the key difference between EEG and ERP’s?
(Ways of investigating the Brain)
EEG records general brain activity while ERPs are obtained using specific stimuli and measuring the brain’s responses to specific events
How do Post-mortems work ?
(Ways of investigating the Brain)
Analysing a person’s brain after their death
For psychological purposes, likely to be those who had a rare disorder and have experienced unusual deficits in mental processes or behaviour
Areas of damage within brain examined after death
Can establish the likely cause of a disorder the person suffered from
If compared with a neuro-typical brain will also show the extent of the damage
Has also identified some of the brain structures involved in memory
What is spatial resolution and what methods are invlolved in it ?
(Ways of investigating the Brain)
Spatial Resolution – the smallest feature or measurement a scanner can detect. If higher, can discriminate between different brain regions more accurately
fMRI – 1-2mm – high – can localise activity specifically
EEG/ERP – Low – only looks at superficial and general regions of the brain
What is temporal resolution and what methods are invlolved in it ?
(Ways of investigating the Brain)
Temporal Resolution – The accuracy of the scanner in relation to time – how quickly it detects changes in brain activity
fMRI – 1-4 seconds – low
EEG/ERP – 1-10 milliseconds – high
What does it mean if a way of investigating the brain is Invasive/Non Invasive ?
(Ways of investigating the Brain)
Invasive/Non Invasive – whether it uses radiation or instruments in the brain
fMRI/EEG/ERP – all non-invasive unlike other techniques
What does it mean if a way of investigating the brain shows causation and how do they display it ?
(Ways of investigating the Brain)
Causation – whether it can show cause and effect
fMRI – not a direct measure of neural activity – only measures changes in blood flow not activity of individual neurones
EEG – electrical activity often detected in several regions of the brain – difficult to pinpoint the exact region of the activity. Only detects activity in superficial areas – can’t detect activity in deeper regions
ERPs – allows determination of how brain processing is affected by a specific experimental manipulation
Post-Mortems – the deficit displayed during lifetime may not be linked to the deficits found in the brain. But allows for detailed examination of the brain at a much deeper level
What is a biological rhythm ?
(Circadian Rhythms and Endogenous Pacemakers and Exogenous Zeitgebers)
Patterns of changes in body activity that conform to cyclical time periods.
Influenced by:
Internal body clocks – Endogenous Pacemakers
External changes in the environment – Exogenous Zeitgebers
What are the three types of biological rhythm ?
(Circadian Rhythms and Endogenous Pacemakers and Exogenous Zeitgebers)
Circadian – 24 hours
Infradian – over 24 hours
Ultradian – under 24 hours
What is the sleep wake cycle ?
(Circadian Rhythms and Endogenous Pacemakers and Exogenous Zeitgebers)
sleeping and awake is controlled by circadian rhythms
External signals (Exogenous Zeitgebers) – light and dark – determine when we feel the need to sleep and wake up
Internal circadian clock is free running – maintaining a cycle of 24-25 hours even without external cues
Intolerant to major alterations
There are dips and rises during the day
What is an endogenous pacemaker ?
(Circadian Rhythms and Endogenous Pacemakers and Exogenous Zeitgebers)
Internal body clocks that regulate many of our biological rhythms
What is the superchiasmatic nucleas and how is it affected by exogenous zeitgeber’s ?
(Circadian Rhythms and Endogenous Pacemakers and Exogenous Zeitgebers)
Light sensitive cells within the eye act as brightness detectors sending messages about environment light levels to the Suprachiasmatic Nucleus
SCN receives information about light from optic nerve even when eyes are shut - adjusts to changing patterns of light while we are asleep
Suprachiasmatic Nucleus (SCN) – main endogenous pacemaker in mammals – known as the “master clock”
How is core body temperature controlled by circadian rhythms ?
(Circadian Rhythms and Endogenous Pacemakers and Exogenous Zeitgebers)
Temperature lowest at about 4:30am (about 36c) and highest at about 6:00pm (about 38c)
Sleep usually occurs when core temperature begins to drop and body temperature starts to rise in the last hours of sleep – makes you more alert
What was the aim, procedure and findings of siffre’s cave experiment ?
(Circadian Rhythms and Endogenous Pacemakers and Exogenous Zeitgebers)
Aim:
To investigate the extent to which endogenous pacemakers (internal body clock) governs sleeping behaviour when deprived of exogenous zeitgebers (external cues)
Procedure
Spent several extended periods underground in caves
Deprived of exposure to natural light and sound
Spent two months in the caves of the Southern Alps
Findings
His ‘free-running’ biological rhythm settled down to one that was just beyond the usual 24 hours (it extended to 25 hours)
He continued to sleep and wake on a regular schedule
What are the two possible conclusion’s of Siffre’s cave study ?
(Circadian Rhythms and Endogenous Pacemakers and Exogenous Zeitgebers)
The small difference in his sleep/wake cycle suggests that our sleeping behaviour is controlled mostly by endogenous pacemakers -
therefore endogenous pacemakers have a key role to play in circadian rhythms such as the sleep wake cycle
Exogeneous zeitgeber’s are somewhat important because without the external cues, his sleep wake cycle changed to 25 hours
Evaluation - Strength – Research Support that Circadian Rhythm is Free-Running – Importance of Endogenous Pacemakers ?
(Circadian Rhythms and Endogenous Pacemakers and Exogenous Zeitgebers)
Point - Siffre – only thing influencing his behaviour was his “free-running” internal body clock (Endogenous Pacemaker) - settled down to around 25 hours – fell asleep and woke at regular intervals demonstrating that circadian rhythms are free-running even in the absence of external cues
I&D– as this is a case study focusing on just one P, it takes an idiographic approach
Evaluation - Limitation – Individual Differences in Circadian Rhythms ?
(Circadian Rhythms and Endogenous Pacemakers and Exogenous Zeitgebers)
Point - Duffy et al - Individuals seem to be innately different in terms of when circadian rhythms start – found that morning people rise early and go to bed early (6am-10pm) whereas evening people prefer to wake and go to bed later (10am – 1am)
Further Individual differences in cycle length – Czeisler et al – found circadian rhythms can vary from 13-65 hours
Evaluation - Strength – Research Support for the Importance of the SCN for Circadian Rhythms ?
(Circadian Rhythms and Endogenous Pacemakers and Exogenous Zeitgebers)
Point - Morgan – Bred mutant hamsters that had circadian rhythms of 20 hours rather than 24 hours – SCN neurons from mutant hamsters transplanted into brains of normal hamsters who subsequently displayed the same abnormal circadian rhythm of 20 hours
Counter – hamsters and humans are very different biologically and environmentally
Evaluation - Strength – Practical Application ?
(Circadian Rhythms and Endogenous Pacemakers and Exogenous Zeitgebers)
Point - Practical application to shift-work – has given researchers a better understanding of the adverse consequences that can occur as a result of the disruption of shift work
Further – practical application to drug treatments – circadian rhythms co-ordinate a number of the body’s basic processes which has an effect on the action of drugs on the body and how well they are absorbed and distributed
