Biopsychology Flashcards
(181 cards)
1
Q
What are the two main divisions of The Nervous System?
A
Central Nervous System
Peripheral Nervous System
2
Q
What does the CNS consist of?
A
Brain and Spinal Cord
3
Q
What are the two main functions of the CNS?
A
Control of behaviour
Regulation of the body’s physiological processes
4
Q
How does the CNS carry out its functions?
A
The brain receives information from the Sensory Receptors (eyes, ears, skin etc.) and sends messages to the muscles and glands using the brain stem to do so
5
Q
What are the four main areas of the brain?
A
Cerebrum
Cerebellum
Diencephalon
Brain Stem
6
Q
What is the Cerebrum?
A
The largest part of the brain Four lobes: - frontal - temporal - parietal - occipital Two hemispheres
7
Q
What is the Cerebellum responsible for?
A
Motor skill
Balance
Coordinating muscles to allow precise movements
8
Q
What does the Diencephalon contain?
A
Thalamus
Hypothalamus (regulates body temp, stress response, hunger and thirst)
9
Q
What does the Brain Stem do?
A
Regulates breathing and heart rate
10
Q
Outline the function of the Spinal Cord?
A
Relay’s information between the Brain and the rest of the body
Allows the brain to monitor and regulate bodily processes and coordinate voluntary movement
Connected to different parts of the body by pairs of spinal nerves which connect to specific muscles/glands
If damaged, body areas connect below the damage will be cut off and stop working
11
Q
What is the Reflex Arc?
A
The Spinal Cord contains circuits of nerves that allow simple reflexes without the brain
12
Q
What does the PNS consist of?
A
The nervous system throughout the rest of the body
13
Q
What does the PNS do?
A
Transmits messages to and from the CNS via neurons
14
Q
What are the two divisions of the PNS?
A
Somatic Nervous System
Autonomic Nervous System
15
Q
Outline the Somatic Nervous System
A
Connects the senses with the CNS Has sensory and motor pathways Controls skeletal muscles and movement Controlled by the motor cortex Involved in reflex arcs
16
Q
What are the two divisions of the Autonomic Nervous System?
A
Sympathetic Nervous System
Parasympathetic Nervous System
17
Q
Outline the Autonomic Nervous System
A
Has only motor pathways
Controls organs and glands of the body
Controlled by the Brain Stem
18
Q
Outline the Sympathetic Nervous System
A
Activated when stressed
Fight or Flight response: Heart rate and breathing increase Digestion stops Salivation reduces Pupils dilate Flow of blood diverted from surface of the skin
19
Q
Outline the Parasympathetic Nervous System
A
Activated when relaxing (conserving energy)
Heart rate and breathing reduce
Digestion starts
Salivation increases
Pupils constrict
20
Q
What is a neuron?
A
Specialised cells that move electrical impulses to and from the CNS
21
Q
What are the parts of a neuron?
A
Cell body - control centre
Nucleus - contains genetic material
Dendrites - receives electrical impulses from other neurons or sensory receptors
Axon - carries electrical impulse from cell body to axon terminal
Myelin Sheath - insulating layer that protects axon and speeds up electrical impulse transmission
Schwann Cells - make up myelin sheath
Nodes of Ranvier - gaps in myelin sheath which speed up electrical impulse along axon
22
Q
What are the three types of neuron?
A
Sensory
Motor
Relay (or Interneurons)
23
Q
Outline Sensory Neurons
A
Carry electrical impulses from sensory receptors to the CNS
Convert information from sensory receptors into electrical impulses
When impulses reach the brain they are converted into sensations so the body can react
Some sensory information terminates at the spinal cord, which allows reflexes to occur quickly
24
Q
Outline Motor Neurons
A
Located in the CNS, project axons outside CNS
Send electrical impulses from CNS to glands/muscles to affect function
Glands and muscles are Effectors
25
Outline Relay Neurons
Connect sensory and motor neurons so they can communicate
| Mostly found in CNS
26
Explain the process of Synaptic Transmission
Neurons transmit action potentials, which must cross the synapse, to other neurons
The synapse is the gap between the pre-synaptic and post-synaptic neuron
Vesicles are sacs containing neurotransmitters (which help transfer AP) on the axon terminal of the pre-synaptic neuron
Exocytosis is the process whereby vesicles release their contents as action potential reaches them
The neurotransmitter diffuses across the synapse and binds to specialised receptor sites which are then activated
The effects are terminated via re-uptake
27
How do psychoactive drugs work?
By increasing or inhibiting the transmission of neurotransmitters across the synapse
28
What do excitatory neurotransmitters do?
They cause an electrical charge in the membrane of the post-synaptic neuron, resulting in an Excitatory Post Synaptic Potential (EPSP). This means the post-synaptic cell is more likely to fire an impulse.
29
What do inhibitory neurotransmitters do?
They cause an Inhibitory Post Synaptic Potential (IPSP) which makes it less likely a neuron will fire an impulse.
30
Define Summation
The net result of the calculation used to determine the likelihood that a cell will fire, which involves adding together the excitatory and inhibitory synaptic input.
31
What does summation determine?
Whether or not a cell will fire an impulse
| More IPSPs means less likely and more EPSPs means more likely
32
What are the two ways the strength of an EPSP can be increased?
Spatial summation
| Temporal summation
33
In Spatial summation...
A large number of EPSPs are generated at many different synapses, on the same post-synaptic neuron at the same time
34
In Temporal summation...
A large number of EPSPs are generated at the same synapse by a series of high-frequency action potentials by a pre-synaptic neuron
35
What is the rate that a cell fires determined by?
What is going on in the synapse:
If more active excitatory synapses, this means a higher rate
If more active inhibitory synapses, this means a lower rate, or possibly no fire at all
36
What does the Endocrine System provide?
A system of communication in the body using the bloodstream
37
What do Endocrine Glands do?
Produce and secrete hormones into the bloodstream which are required to regulate many bodily functions
38
What are the major glands of the Endocrine System?
Pituitary gland
| Adrenal glands
39
What are target cells?
Cells which respond to specific hormones because they have receptors for that hormone.
40
How is a physiological reaction caused?
When enough receptor sites are stimulated by a hormone.
41
Where is the pituitary gland located?
Brain
42
What does the pituitary gland do?
Produces hormones which primarily influence the release of other hormones from other glands.
43
What is the pituitary gland controlled by?
The hypothalamus, region of the brain just above the pituitary gland.
44
The hypothalamus...
Receives information about the body's basic functions and sends a signal to the pituitary gland as a Releasing Hormone.
45
What do Releasing Hormones cause?
They cause the pituitary gland to send a Stimulating Hormone into the bloodstream and tell the target gland to release its hormone.
46
What happens as levels of a hormone increase in the bloodstream?
The hypothalamus stops producing releasing hormone and pituitary gland stops secreting stimulating hormone.
47
What are the two divisions of the pituitary gland?
Anterior
| Posterior
48
What hormone does the Anterior PG release and what is it responsible for?
ACTH, responsible for preparing the body for fight/flight response during stress.
49
What hormone does the Posterior PG release and what is it responsible for?
Oxytocin, responsible for infant/mother bonding.
50
Where are the two adrenal glands situated?
On top of the kidneys.
51
What are the two parts each of the adrenal glands are made up of?
Adrenal Cortex
| Adrenal Medulla
52
What is the Adrenal Cortex?
The outer section of the adrenal gland.
| Produces Cortisol
53
What is Cortisol responsible for?
It is produced in high amounts when stressed.
| Responsible for the cardiovascular system.
54
What is the Adrenal Medulla?
The inner section of the adrenal gland.
| Produces Adrenaline and Noradrenaline, needed for fight or flight.
55
What is adrenaline responsible for?
Increasing heart rate
Dilating pupils
Stopping digestion
56
What is noradrenaline responsible for?
Constricting blood vessels, which increases blood pressure
57
What is the Amygdala and what does it do?
It is an area of the brain which associates sensory signals with emotions linked to fight or flight (fear, anger).
When a threat is sensed, the amygdala sends a distress signal to the hypothalamus.
58
Response to Acute Stress:
| Explain the Sympathomedullary Pathway
When SNS is triggered by the hypothalamus, it sends a signal to the adrenal medulla, which releases adrenaline.
59
Response to Acute Stress:
| Adrenaline will...
Increase heart rate
Constrict blood vessels
Increase the rate of blood flow
Raise blood pressure
Divert blood away from the skin, kidneys and digestive system
Increase blood supply to the brain and skeletal muscles
Increase respiration and sweating
This prepares the body for fight or flight by providing energy and rapid response planning resources.
60
Response to Acute Stress:
| What does the Parasympathetic Nervous System do?
Dampens stress response when the threat is gone.
61
What happens if the brain continues to see something as a threat?
HPA axis kicks in (Hypothalamus, Pituitary Gland, Adrenal Glands)
62
In response to chronic stress, what does the hypothalamus do?
Releases the chemical messenger CRH (corticotrophin-releasing hormone) into the bloodstream.
63
In response to chronic stress, what does the pituitary gland do?
The CRH causes it to release ACTH which is transported in the bloodstream to the adrenal glands where its target sites are.
64
In response to chronic stress, what do the adrenal glands do?
ACTH will cause the adrenal cortex to release cortisol, which can give a quick burst of energy and lower sensitivity to pain, but also impair cognitive performance and immune system.
65
What happens if cortisol levels get too high?
Hypothalamus and pituitary gland have special receptors to monitor cortisol levels so if they get too high they reduce CRH and ACTH back to normal.
66
Fight or Flight positive evaluation points:
- From an evolutionary point of view, it makes sense because people would have been able to survive a threat by fighting or fleeing
- People whose adrenal glands malfunction do not have a normal fight or flight response, supporting the idea that adrenaline is essential for the body's response to stress
67
Fight or Flight negative evaluation points:
- A psychologist says the first reaction to stress is to freeze (stop, look, listen and be hyper vigilant)
- Females tend and befriend in times of stress because they have oxytocin which means they are likely to stay and protect their offspring
- A psychologist found that males can tend and befriend, e.g. during 9/11 both males and females showed this
68
Define localisation of function
The idea that specific functions have specific locations in the brain
69
Where is the Visual Cortex located?
The Occipital lobe and spans both hemispheres
70
Where is the Auditory Cortex located and what does it do?
The temporal lobe and spans both hemispheres
| Contains several areas which process different visual info
71
Explain visual processing
Processing begins in the retina
Light enters and strikes photoreceptors and nerve impulses are transmitted via the optic nerve, from the retina to the brain.
Most stop in the thalamus, which acts as a relay station and passes the info to the visual cortex
72
Outline the auditory pathway
It begins in the cochlea (in the inner ear). Here, sound waves are converted to nerve impulses which travel to the auditory cortex via the auditory nerve.
The brain stem then decodes, it goes to the thalamus for further processing and is then relayed to the auditory cortex
73
Where is the motor cortex located?
The frontal lobe of both hemispheres along the 'precentral gyrus'
74
What is the motor cortex responsible for?
The generation of voluntary motor movements
| Different parts control different body parts and are arranged logically next to each other.
75
Where is the somatosensory cortex located?
The parietal lobe of both hemispheres along the 'postcentral gyrus'
76
What does the somatosensory cortex do?
It detects sensory events arising from different regions of the body
Using sensory info from the skin it produces sensations of touch, pressure, pain, and temperature then localises these to specific body parts
77
Where is Broca's area located?
Left frontal lobe
78
Where is Wernicke's Area located?
Temporal lobe
79
What is Broca's Area responsible for?
Speech production
| Responding to demanding cognitive tasks
80
What is Wernicke's Area responsible for?
Processing spoken language
81
What are Broca's area and Wernicke's Area connected by?
A neural loop called the Arcuate Fasciculus
82
Positive evaluation of localisation of function
Expressive Aphasia - impaired ability to produce language caused by damage to Broca's Area
Receptive Aphasia - impaired ability to understand language caused by damage to Wernicke's Area
83
Negative evaluation of localisation of function
- Some functions such as motor and somatosensory functions are more localised than others such as personality
- Equipotentiality theory says higher mental functions are not localised and that if an area is injured, other areas of the cortex will take over responsibility for those areas cognitive functions
- Two of Broca's patients' brains were re-examined and MRI scans found that many areas were damaged; lesions to Broca's area do cause temporary speech disruption, but language skills are more widely distributed
- When observing activity in the right temporal lobe, left frontal lobe and occipital lobe, it was found there are individual differences in which brain areas are activated during silent reading
- How brain areas communicate could be more important than specific areas. There was a patient who could not read due to damage between the visual cortex and Wernicke's area
84
Define lateralisation of function
The idea that the two hemispheres have different specialisations.
85
What has research found the left and right hemispheres are each dominant for?
Left for language
| Right for facial recognition
86
What are the two hemispheres connected by?
A bundle of nerves called the Corpus Callosum
87
Which sides of the body are each of the hemispheres responsible for?
Visual, auditory, motor and somatosensory cortexes in the left hemisphere control the right side of the body and vice versa.
88
Positive evaluation of lateralisation of function
- Brain lateralisation increases neural processing capacity because if using one hemisphere for a task, the other is free for other functions. It was found that lateralisation in chickens aids the ability to multitask (find food and be vigilant for predators)
- Architects and mathematicians tend to have superior right hemispheres
89
Negative evaluation of lateralisation of function
JW, after a split brain procedure, developed the ability to speak using the right hemisphere and could, therefore, speak about information which was presented to their left or right hemisphere.
90
What is a split-brain patient?
Usually, they are somebody who underwent surgery whereby their corpus callosum was cut to prevent electrical activity caused by epileptic seizures from crossing hemispheres.
91
What did Sperry and Gazzaniga (1968) find when investigating split-brain patients?
Information in the left visual field goes to the right hemisphere and vice versa and in split-brain patients, the information cannot travel to the other hemisphere due to the severed corpus callosum.
92
Outline the test used on split-brain patients
Patients have to stare at a dot in the centre of a screen where information is presented to either the left or right visual field.
They are asked to respond verbally or with their left/right hand without seeing what their hands are doing.
For example, they could be flashed an image of a dog to the right visual field and be able to say dog because it was shown to the left hemisphere, where language centres are.
If shown to the left visual field, they will not be able to say but could draw a picture of what they saw
93
Negative evaluation of split-brain research
- Some patients have a larger disconnection between hemispheres and some have drug therapy for epilepsy longer than others, both of which can affect the way their brain works
- It is not valid to compare people with epilepsy to a control group without it
- Most studies use very small numbers of participants, making it hard to generalise results
- In the real world, split-brain patients are able to use both visual fields without restrictions and so their condition can be compensated for
94
What is meant by the term 'Brain Plasticity'?
The brain's ability to adapt due to experience
| Plasticity allows the brain to deal with the indirect effects of brain damage (e.g. swelling)
95
How can life experience effect plasticity?
Frequently used nerve pathways develop stronger connections and ones rarely used die. This allows the brain to adapt to a changing environment.
There is also a decline in cognitive function with age due to these changes, researchers are looking for ways to reverse this decline
96
What did Boyke et al. (2008) do and find?
Boyke taught 60-year-olds to juggle, which is a new skill and this increased grey matter in the visual cortex
97
What did Kuhn et al. (2014) do and find about video games?
Kuhn et al compared a control group to a group given 30 minutes of video game (Super Mario) training per day for 2 months.
They found playing video games significantly increased grey matter in the visual cortex, hippocampus, and cerebellum.
Playing causes new synaptic connections in the brain areas involved in spatial navigation, strategic planning, working memory and motor performance.
98
What did Davidson et al. (2004) do and find about meditation?
They compared eight Tibetan Meditation practitioners to ten students who had never meditated.
Greater gamma wave activity was picked up using electrical sensors in the monks, even before meditating.
99
What do gamma waves do?
Coordinate neural activity
100
Plasticity positive evaluation
- A psychologist found that rats in complex environments compared to lab rats had more new neurons in their brains, most prominent in the hippocampus (navigation and forming new memories)
- A psychologist measured grey matter in London Taxi Drivers brains using MRI. Their hippocampus' was much larger than the control groups and correlated with how long they had been taxi drivers
101
Define Functional Recovery
The idea that the brain can sometimes recover from trauma, it is more likely at a younger age when the brain is still maturing
102
Define Neural Reorganisation
The transfer of functions from damaged areas to undamaged ones
103
Define Neural Regeneration
The growth of new neurons and connections to compensate for damaged areas
104
What did Wall (1977) identify in the brain?
Dormant Synapses
105
Define Dormant Synapse and explain neuronal unmasking?
Dormant synapses are synaptic connections which are anatomically there but have blocked function.
They are normally ineffective because the rate of neural input to them is too low to activate them.
Increasing the rate (which would happen if a surrounding brain area was damaged) can activate them.
This can open connections to areas of the brain not normally activated which can lead to the development of new brain structures.
106
What are stem cells?
Unspecialised cells that have the potential to become many cells that carry out different functions.
Stem Cells implanted in the brain could potentially replace dead or dying cells.
107
Positive evaluation of functional recovery
- A psychologist studied rats with brain injuries and gave one group stem cell transplants into the affected area. Three months later, those rats showed the development of neuron-like cells in the damaged area.
- Studies have shown that abilities thought to be fixed in childhood can still be modified in adults, but it takes intensive retraining.
108
Negative evaluation of functional recovery
- A psychologist found that the capacity for neural reorganisation after brain injury is greater in children than adults.
- A psychologist found that patients with college educations are 7X more likely than those who did not finish secondary school to be disability-free a year after a moderate to severe brain injury. They concluded that Neural Reserve could be a factor in functional recovery.
109
What are the four main methods of studying the brain?
Post-mortem examinations
fMRI (functional magnetic resonance imaging)
EEG (electroencephalogram)
Event-related potentials
110
Explain Post-Mortem examinations
When somebody dies, psychologists can look for abnormalities in the brain that explains an interesting behaviour they displayed whilst alive.
Post-mortems have found links between brain abnormalities and psychiatric disorders, e.g reduced Glial Cells in the frontal cortex of depression patients.
111
What is an advantage of Post-Mortem?
They allow a more detailed examination of anatomical and neurochemical aspects of the brain and have enabled researchers to examine deeper regions such as the hippocampus.
112
What is a disadvantage of Post-Mortem?
Could lack validity due to small sample size and because people die in many circumstances which can affect the brain.
The length of time between death and post-mortem and drug treatments can also affect the brain.
113
Explain fMRIs
It uses magnetic fields and radio waves to monitor blood flow in the brain.
Measures the change in the energy released by haemoglobin which reflects the activity of the brain to give a moving picture of the brain.
Activity in specific regions can be compared during a baseline task and during specific activity.
114
What is an advantage of fMRI?
It captures dynamic brain activity compared to post-mortem/MRI which show only the physiology.
115
What is a disadvantage of fMRI?
Interpreting fMRI is complex and affected by temporal resolution, biased interpretation and the baseline task used.
Research is expensive, leading to reduced sample sizes.
116
Explain EEGs
It measures general electrical activity in the brain, often states such as sleep and arousal.
Electrodes placed on scalp detect neuronal activity directly below position.
Different numbers of electrodes can be used based on the focus of research.
Electrical signals from different electrodes are graphed over a period of time and the result is called an EEG pattern.
117
What do EEG patterns of epileptic patients show?
Spikes of electrical activity
118
What do EEG patterns of those with brain injuries show?
A slowing of electrical activity
119
What is an advantage of EEGs?
Useful in clinical diagnosis - it can record the neural activity associated with epilepsy so doctors can confirm the person is having seizures
Also cheaper than an fMRI
120
What is a disadvantage of EEGs?
Poor spatial resolution
121
Explain Event-Related Potentials
Electrodes are placed on the scalp which will detect neuronal activity in response to a stimulus the researcher presents. The stimulus must be presented many times and the responses averaged to establish a specific response, as ERPs are difficult to differentiate from other brain activity.
Extraneous activity will not occur consistently, but specific responses will.
122
What are sensory ERPs?
They are ERP waves generated in the first 100 milliseconds of the stimulus being presented.
They reflect the initial response.
123
What are cognitive ERPs?
They are ERP waves generated after the first 100 milliseconds of the stimulus being presented.
They reflect the way the stimulus has been evaluated and demonstrate information processing.
124
What is an advantage of ERPs?
They can measure the processing of a stimulus even in the absence of a behavioural response making it possible to measure it covertly.
125
What is a disadvantage of ERPs?
It can only record sufficiently strong voltage changes generated across the scalp and activity deeper in the brain is not recorded.
ERP generation tends to be limited to the neocortex.
126
Define Biological Rhythms:
Cyclical changes in physiological systems which evolved due to the environments own cyclical changes such as d
time of day and seasons.
127
What are the three types of biological rhythm?
Circadian
Ultradian
Infradian
128
What are circadian rhythms?
Any cycle which lasts 24 hours
Most organisms have a biological representation of the 24 hour day which optimises their physiology and behaviour to fit the day/night cycle.
129
What are circadian rhythms driven by?
The Suprachiasmatic nuclei (SCN) in the hypothalamus
130
Why must the SCN constantly be reset?
So that our bodies are syncronised with the outside world
131
What is a pacemaker?
Controls the rate at which something occurs
132
What is photoentrainment?
A process which uses natural light to set the body clock to the correct time
133
What do light-sensitive cells in mammals do?
They act as brightness detectors which send messages to the SCN - which uses this information to coordinate the activity of circadian rhythms - about the environmental light.
134
The Sleep-Wake cycle is...
... a Circadian Rhythm
135
What are the external signals that determine when we feel awake or sleepy?
Light and Darkness
136
When do the strongest sleep drives occur?
2:00-4:00am and 1:00-3:00pm
137
Sleep and wakefulness are under...
... Homeostatic control
138
Outline the role of homeostasis in the sleep-wake cycle?
When we have been awake for a long time, it tells us that the need for sleep is increasing because of the amount of energy used up during wakefulness. Throughout the day, the drive for sleep increases gradually the more energy is used and reaches a maximum during the late evening.
139
What does the circadian system do?
Keeps us awake whilst there is daylight and tells us to sleep when it is dark. It maintains a cycle of 24-25 hours even without natural light.
140
What does the homeostatic system do?
Makes us sleepier the longer we have been awake, regardless of whether it is night or day.
141
When is your core body temperature at its lowest and what is it?
36°C at 4:30 am
142
When is your core body temperature at its highest and what is it?
38°C at 6:00 pm
143
When does sleep occur?
When core temperature begins to drop
144
When does body temperature begin to rise and what does this do?
In the last few hours of sleep, it prompts a feeling of alertness in the morning.
145
Hormone release follows...
... a circadian rhythm
146
What hormone is released from the pineal gland?
Melatonin
147
What gland releases melatonin?
Pineal gland
148
When does the release of melatonin peak?
During hours of darkness
149
What does melatonin do and how?
Melatonin induces sleep by inhibiting the neural mechanisms which promote wakefulness
150
EVALUATION POINT: What is a practical application of circadian rhythms?
Chronotherapeutics
For example, the risk of heart attack is highest during early morning after waking and so medications have been developed that are taken before sleeping but not released until 6:00 am.
151
What are some negative evaluation points of Circadian Rhythms?
- It was believed only natural light affects circadian rhythms, but more recent studies would disagree. A psychologist altered participants circadian rhythms down to 22 hours and up to 28 hours using artificial light.
- Individual differences in lengths. A study found that cycles can vary from 13 to 165 hours.
- Individual differences in peak times - 'morning people' prefer to rise early and sleep early whereas 'evening people' prefer to rise late and sleep late.
- Some believe temperature controls our body clock. The SCN transforms information about light levels into neural messages which set the temperature and these fluctuations set the timings of cells.
152
What is an Ultradian Rhythm?
Ones which last less than 24 hours
153
What is an example of an ultradian rhythm?
The 5 sleep stages
154
What are the 5 sleep stages?
```
Light Sleep
Sleep
Deep Sleep
Very Deep Sleep
^ Non-Rapid Eye Movement (NREM)
Rapid Eye Movement (REM)
```
155
How often does the sleep cycle repeat?
Every 90 minutes
156
Describe the EEG patterns of the stages of sleep?
Each stage shows a distinct pattern
| Brainwaves, breathing and heart rate slows when entering deep sleep.
157
What happens during REM?
The EEG pattern resembles an awake person and dreaming occurs during this stage.
158
What did Kleitman (1969) refer to the 90-minute sleep cycle as?
The Basic Rest Activity Cycle (BRAC)
159
What did Kleitman suggest (1969)?
That the 90-minute cycle continues when awake and rather than the sleep stages, we go from states of alertness to physiological fatigue.
Research suggests that we can focus for about 90 minutes and after we begin to run out of resources. This results in loss of concentration, fatigue and hunger.
160
What is an Infradian Rhythm?
One which lasts more than 24 hours
161
What is an example of an infradian rhythm?
The menstrual cycle (lasts 28 days on average)
162
What regulates the menstrual cycle?
Hormones
163
When does ovulation occur and for how long?
Roughly halfway through the cycle and for 16-32 hours
164
What happens after ovulation?
Progesterone levels increase in preparation for the implantation of an embryo
165
What are two positive evaluation points for ultradian and infradian rhythms?
- A psychologist found support for BRAC when they studied a group of elite violinists. They found that practice sessions were limited to 90 minutes and they often napped after to recover, the best violinists napped more. This was found in athletes, chess players and writers also.
- Infradian rhythms can affect behaviour - it was found that women prefer feminised male faces when choosing long term partners, but prefer masculinised faces when ovulating.
166
What are two negative evaluation points for ultradian and infradian rhythms?
- There could be individual differences in sleep patterns which are biologically determined. Participants were studied over 11 days in a lab. Researchers assessed sleep duration, the time taken to fall asleep and time in each stage and found differences in each.
- The menstrual cycle is not only based on infradian rhythms. When several women of childbearing age live together and do not take oral contraceptives, their cycles synchronise. A study collected sweat samples of women and rudded onto the upper lip of another group of women and their cycles became synched, suggesting it is affected by pheromones.
167
What is an Endogenous Pacemaker?
Internal biological rhythms
168
What is an Exogenous Zeitgeber?
External factors such as light
169
Why do we have endogenous pacemakers and exogenous zeitgebers?
To reset our biological rhythms each day and keep them in tune with the outside world.
170
What is the most important Endogenous Pacemaker and what is it?
The Suprachiasmatic Nuclei (SCN) which is a tiny cluster of nerve cells in the hypothalamus.
171
What does the SCN do?
Acts as a master clock, linking other brain areas that control sleep and arousal and controlling all other biological clocks.
Regulates the manufacture and secretion of melatonin in the pineal gland via the interconnecting neural pathway.
172
How does the SCN regulate Melatonin?
It sends a signal to the pineal gland telling it to increase production and secretion at night and to decrease as light levels increase.
173
What does melatonin do?
induces sleep by inhibiting the parts of the brain which promote wakefulness
174
How does the SCN receive information about light levels?
through the optic nerve
175
Neurons within the SCN...
...synchronise with each other so that their target neurons receive time-coordinated signals
176
What is research which supports Endogenous Pacemakers?
+ A strain of hamster was bred with abnormal circadian rhythms of 20 hours and SCN neurons from them were put in normal ones and they displayed abnormal rhythms after
+ Kate Aldcroft spent 25 days in a lab with no daylight and her core temperature rhythm was still 24 hours after
177
What is research that does not support Endogenous Pacemakers?
- Kate Aldcroft's sleep-wake cycle extended to 30 hours where she slept for as long as 16 hours, meaning we need external influences to maintain our circadian rhythms
178
What is the most important Exogenous Zeitgeber?
Light
179
How does light affect circadian rhythms?
Receptors in the SCN are sensitive to changes in light levels during the day and use this to synchronise the activity of organs and glands.
It resets the internal biological clock each day
180
What is melanopsin?
A protein in the retina of the eye which is sensitive to natural light
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What is research which supports exogenous zeitgebers?
+ The vast majority of blind subjects who still have some light perception have normal circadian rhythms as opposed to those without light perception
+ Exposure to bright light prior to an east-west flight decreased the time needed to readjust to local time
+ The sleep-wake cycle and activity-rest patterns of two groups of participants were compared over 5 weeks. One group was in normal warm artificial light, the other in blue light. They kept a sleep log and a device measured their movement. Participants in warm synchronised with the natural light of dawn and in blue light synchronised to office hour patterns.
