1
Q
What is the nervous system?
A
- Specialised network of cells which work as a communication system
- Collects and responds to info in the environment
- Co-ordinates the working of different organs and cells
- Made up of Central nervous system and Peripheral nervous system
2
Q
Central Nervous System
A
- Brain = conscious awareness
- 2 hemispheres
- Outer layer called cerebral cortex
-2. Spinal chord = transfers messages to and from the brain
- Connects nerves to the PNS
- Reflexes
3
Q
Peripheral nervous system
A
- Role to relay messages from the CNS to the rest of the body
- Somatic and autonomic nervous system
4
Q
Somatic nervous system
A
Carries sensory information from the outside world to the brain via the CNS and provide muscle responses via the motor pathways.
5
Q
Autonomic Nervous system
A
Homeostasis, which maintains vital internal processes like body temperature and heart rate. Consists of the sympathetic and parasympathetic nervous system.
6
Q
Function of the sympathetic and parasympathetic nervous system
A
- The sympathetic nervous system is involved in the body’s preparation for fight or flight, impulses travel to organs in the body to help us prepare for danger, e.g. our heart rate increase whilst less important functions like digestion are suppressed.
- The parasympathetic nervous system is involved in relaxing the body, and returning us to a ‘rest and digest’ state after threat.
7
Q
The endocrine system
A
- Gland is an organ that synthesises substances such as hormones
- The thyroid gland e.g. produces thyroxine which affects cells in the heart (increases heart rate)
- It also affects cells throughout the body, affecting metabolic rates (growth)
8
Q
Hormones
A
- Chemicals that circulate in the bloodstream and are carried to target sites throughout the body
- Each hormone stimulates that area of the body
- Only affects certain cells
- Target cells respond to a particular hormone because they have receptors to that hormone
9
Q
Outline one difference between the nervous system and the endocrine system
A
- One difference between the two is the time it takes for the systems to respond to stimuli
- The nervous system reacts from electrical and chemical transmission and the response is near instantaneous
- The endocrine system reacts much more slowly but has a much longer lasting and widespread effect
10
Q
Describe the fight or flight response
A
- A person enters a stressful/ dangerous situation
- The amygdala is activated which send a distress signal to the hypothalamus
- The hypothalamus activates the sympathetically pathway - running to the adrenal medulla and the sympathetic nervous system
- The SNS stimulates the adrenal medulla, part of the adrenal gland
- The adrenal medulla secretes the hormones adrenaline and nor adrenaline into the bloodstream
- Adrenaline causes a number of physiological changes to prepare the body for fight or flight
- e.g. increased HR, BR, pupil dilation, sweat production, etc.
11
Q
What is a neuron?
A
Nerve cells that process and transmit messages through electrical and chemical impulses in the nervous system
12
Q
Name 3 types of neuron
A
Sensory, relay, motor
13
Q
Describe the general structure of a neuron
A
- Dendrites are branch-like structures that receive nerve impulses from neighbouring neurons or sensory receptors and carry them to the cell body
- The cell body includes the nucleus which contains the genetic material
- The axon carries impulses, in the form of action potential, away from the cell body down the length of the neuron to the axon terminal
- The axon is insulated by the myelin sheath to protect it and speed up impulses
- The myelin sheath is segmented by the Nodes of Ranvier which are gaps between the that speed up the transmission of impulses by forcing the impulsion to jump across the gaps
- Terminal buttons are at the end of the axon; these communicate with the next neuron across the synapse
14
Q
Describe the different types of neuron
A
- Motor neurons are found in the CNS and connect the CNS to effectors e.g. muscles to control muscle movements, when stimulated release neurotransmitters that bind to receptors to trigger a response movement
- Relay neurons are found between sensory input and motor output, found in the brain and spinal cord, and allow sensory and motor neurons to communicate
- Sensory neurons carry messages from the peripheral nervous system to the CNS, found in receptors such as the eyes and carry nerve impulses to the brain to translate into sensations e.g. vision
15
Q
Describe the process of synaptic transmission
A
- Action potential arrives at presynaptic neuron
- Neurotransmitter is released from vesicles
- Neurotransmitter diffuses across synapse
- Neurotransmitter binds to postsynaptic receptor - chemical transmission of impulse - results in excitation or inhibition
- Neurotransmitter is reabsorbed into presynaptic neuron, broken down and reused
16
Q
Explain and distinguish between electrical and chemical transmission in relation to neurons
A
- Electric transmission happens within the neuron
- This changes the neuron from being negatively charged to positively charged when activated by stimulus
- This then creates the electrical impulse that travels to the end of the neuron - Chemical transmission occurs between neurons
- When an electrical impulse reaches the end of the neuron it triggers the release of neurotransmitters
- These diffuse across the synapse
17
Q
Explain the function of a neurotransmitter and give an example
A
- Is a chemical released from the presynaptic nerve that relays a signal across the synapse
- The neurotransmitter diffuses across the synapse and is taken up by the postsynaptic receptor site
- The chemical message is then converted back into an electrical impulse
- e.g. acetylcholine is found where the motor neuron meets a muscle and causes the muscle to contract
18
Q
In terms of synaptic transmission, explain what is meant by inhibition and excitation
A
- Some neurons are excitatory, and some are inhibitory
- Excitatory make the post synaptic cell more likely to fire e.g. adrenaline
- Inhibitory less likely e.g. serotonin
19
Q
Describe what is meant by localisation and holistic theory of the brain
A
- For a long time scientists believed the brain functioned holistically
- All parts of the brain are involved in processing thoughts and actions
- Research by Paul Broca and Carl Wernicke in the 19th Century lead to the discovery of localisation of function
20
Q
Name the 4 lobes of the cerebral cortex
A
Parietal lobe, Occipital lobe, Temporal lobe, Frontal Lobe
21
Q
Name and describe the 4 for areas of cortical specialisation in the brain
A
- The motor cortex is responsible for voluntary motor movements - rear frontal lobe - opposite side.
- The somatosensory cortex detects and processes information relating to touch using sensory info from the skin e.g. pressure.
- The visual cortex is in the occipital lobe at the back of the brain - right visual cortex receives information from the left visual field and vice versa.
- The auditory cortex is in the temporal lobe and concerned with the analysis of speak based info e.g. hearing.
22
Q
Broca’s area
A
-Paul
- Patient Tan could understand spoken language but was unable to produce any coherent words, and could only say Tan
- Damage in the left frontal lobe
- Responsible for speech production
- Damage results in Brocas aphasia, which results in slow and inarticulate speech
23
Q
Wernicke’s area
A
- Karl
- Left temporal lobe
- Fluent but meaningless speech
24
Q
What is hemispheric lateralisatin
A
- Lateralisation is the idea that the two halves of the brain are functionally different and that each hemisphere has functional specialisations
- The two hemispheres are connected through nerve fibres called the corpus callosum, which allows the two hemispheres to communicate
- Some functions are not lateralised e.g. our motor functions
25
What has research shown about the left and right hemispheres
- Language in left and is lateralised e.g.analysing, detail, numbers
- Emotional context and holistic understanding in the right e.g. synthesiser, visual, bigger pic
26
What is meant by 'contralateral' and 'ipsilateral' in the context of hemispheric lateralisation
- In the case of motor functions, the brain is contralateralised
- Vision is also not lateralised
(both contralateral and ipilateral)
- Ipsilateral is the opposite of contralateral where the same hemisphere is wired the same side of the body
- Each eye has a LVF and RVF
- The LVF in both eyes is wired to the right hemisphere and vice versa
27
Sperrys study
- 11 individuals had serious epilepsy with their corpus callosum severed, which allowed sperry to investigate if the two hemispheres were specialised for certain functions
- Image or words would be projected to the right or left visual field (stops hemispheres communicating)
- Finding 1: Images presented in the LVF could not be described verbally but in the RVF could
Finding 2: Although they could not describe objects in the left field, they could identify them by touch and they could draw them using their left hand
- These observations show how certain functions in the brain are lateralised
e.g. LH is verbal whereas the RH is silent and RH processes emotions, LH doesn't
28
What is meant by plasticity
- The brains tendency to change and adapt as a result of new experience / learning
- The experiences that we have result in some neural pathways being strengthened, some being altered, and others being lost - synaptic pruning.
29
Outline one research study into plasticity
- Macguire et al
- London taxi drivers have significantly more grey matter in their posterior hippocampus
- Development of spatial and navigational skills
- Result of the 'knowledge'
- Positive correlation between time spent as a driver and the difference to a control group
30
What is functional recovery
- A form of brain plasticity that occurs following injury or trauma, unaffected areas of the brain are often unable to adapt to compensate for the areas that are damaged
- Brain can redistribute functions usually performed by the damaged areas, to undamaged areas
- Spontaneous recovery than slows down may require rehabilitative therapy
31
What happens in the brain during functional recovery?
- Neuronal unmasking is where secondary pathways that are not normally used and lay dormant are activated or uncovered
- Structural changes in the brain:
1. Axonal sprouting (growth of new nerve endings)
2. Denervation supersensitivity (secondary neurons become aroused to a higher level to compensate for the loss)
3. Recruitment of similar areas on the opposite side of the brain
32
Name 4 ways of investigating the brain
fMRI, EEG, ERP, postmortem
33
fMRIs
- Functional magnetic resonance imaging is a brain scanning technique that measures blood oxygenation and flow in the brain when a person performs a task
- fMRI works on the premise that neurons in the brain that are the most active during a task use the most energy and thus require oxygen
- An increase in blood flow is a response to the need for more oxygen in that area of the brain when it becomes active, suggesting an increase in neural activity
- Oxygenated and deoxygenated blood have different properties
34
EEG
- An electroencephalogram works on the premise that information is processedd in the brain as electrical activity in the form of action potentials or nerve impulses, transmitted along neurons
- Measure electrical activity through electrodes attached to the scalp
- Small electrical charges detected by the electrodes are graphed over a period of time, indicating the level of activity in the brain
- Can be used to detect illnesses like epilepsy and sleep disorder and diagnose other disorders that affect brain activity, like Alzheimer disease
35
ERP
- Event Related Potentials use electrodes attached to the scalp
- A stimulus is presented to a participant and the researcher looks for activity related to that stimulus
- Difficult to separate from all of the background EEG data, the stimulus is present many times and an average response is graphed
- This procedure which is called averaging reduces any extraneous neural activity which makes the specific response to the stimulus stand out
36
Postmortems
- An analysis of the brain following death, usually involving people who had rare disorders or unusual deficits whilst alive
- Areas of damage examined to establish the likely cause of the atypical behaviour
- Comparison to neurotypical brains
37
What is a biological rhythm?
- Distinct patterns of changes in body activity that conform to cyclical time periods
- Influenced by internal body clocks and external changes to the environment
38
Explain what is meant by a circadian rhythm and give an example
- A type of biological rhythm subject to a 24 hour cycle which regulates a number of body processes
e.g. the sleep wake cycle or changes in core body temperature
39
Describe the sleep wave cycle
- Dictates when humans are asleep and awake
- Light provides the primary input to this system, acting as the external cue for sleeping or waking. Light is first detected by the eye, which then messages concerning the level of brightness to the suprachiasmatic nucleus (SCN)
- The SCN then uses this information to coordinate the activity of the entire circadian system
40
Describe what is homeostatic control in relation to the sleep wake cycle
A 'free running circadian rhythm falls under homeostatic control. When an individual has been awake for a long-time energy consumption makes us sleep, regardless of day or night.
41
Describe the purpose, procedure, and findings from Siffre's Cave study
Siffre is a 'self-styled caveman' who has spent several extended periods underground to study the effects on his own biological rhythms. He was completely deprived of exposure to natural light and sound but had access to adequate food and drink. Resurfaced after 2 months in the caves where he thought it was august not September. This shows the power of natural light.
42
Describe the findings from other research into circadian rhythms
- Boivin et al
- Night shift workers experience a dip in concentration in certain hours
43
Describe other circadian rhythms
- Body temperature
- Human body temperature is at its lowest in the early hours of the morning (36 degrees at 4:30 am) and at its highest in the early evening (38 degrees at 6 pm)
- Sleep typically occurs when the core temperature starts to drop, and the body temperature starts to rise towards the end of a sleep cycle promoting feelings of alertness first thing in the morning
44
What is an infradian rhythm and examples?
- A type of biological rhythm that lasts longer than 24 hours and can be weekly, monthly, or annually
- The menstrual cycle is governed by monthly changes in hormones
- Seasonal affective disorder
45
Outline the menstrual cycle as an infradian rhythm
- A monthly infradian rhythm is the female menstrual cycle, which is regulated by hormones that either promote ovulation or stimulate the uterus for fertilisation
- Ovulation occurs roughly halfway through the cycle when oestrogen levels are at their highest, and usually lasts for 16-32 hours
- After the ovulatory phase, progesterone levels increase in preparation for the possible implantation of an embryo in the uterus
-23 to 36 days
46
Describe seasonal affective disorder with reference to infradian rhythms
- Seasonal variation in mood, where some people become depressed in the winter e.g. low mood, general lack of activity, etc.
- The lack of light during the winter months results in a longer period of melatonin secretion which affects serotonin production
47
What is an ultradian rhythm and an example
- A type of biological rhythm that occurs more than once in a 24-hour period (lasts less than 24 hours)
- E.g. the sleep cycle
48
Outline the sleep cycle
Stage 1 and 2: 'Light sleep' stages, brainwave patterns become slower and more rhythmic (alpha to beta)
Stages 3 and 4: 'Deep sleep', slower delta waves
49
Outline the nature of endogenous pacemakers
- Internal mechanisms that govern biological rhythms, in particular, the circadian sleep-wake cycle
- Can be altered and affected by the environment e.g although the circadian sleep-wake cycle will continue to function without natural cues from light, research suggests that light is required to reset the cycle every 24 hours
- Suprachiasmatic nucleus is closely linked to the pineal gland which is closely linked to the sleep-wake cycle
50
Describe the suprachiasmatic nuceus
- Controls circadian rhythms
- Small region of the brain in the hypothalamus
- Receives direct input from the eyes, via the optic nerve, particularly about light exposure
- Information about light levels is then passed on to the pineal gland, which uses the information to regulate melotonin production
51
Outline some research into the importance of endogenous pacemakers on biological rhythms
- DeCoursey et al
- Damaged the SCN in chipmunks then released them into the wild
- Sleep wake cycle was affected (didn't sleep when they were supposed to)
- Most of them died because they didn't sleep at the right time
52
What are exogenous zeitgebers
Environmental events that are responsible for resetting the biological clock of an organism.
53
Name and describe 2 exogenous zeitgebers
1. Light
Exposure to natural light helps align our internal clock with the 24 hour day - entertainment
2. Social cues help to regulate the bodies internal clock by providing regular patterns of activity and rest - they help to synchronise our biological clocks with the external environment
Psych
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