Studied by 3 people
Describe the two divisions of the nervous system
central nervous system
peripheral nervous system
2 main functions of the nervous system
collect, process and respond to information in the environment
co-ordinate the working of organs and cells
What does the central nervous system contain? (NS)
the brain (processes info)
the spinal cord (receives & transmits info)
the brain
centre of all conscious awareness
cerebral cortex - 3mm
highly developed, differentiates us from other animals
spinal cord
extension of brain
passes messages to and from brain
connects nerves to PNS
responsible for reflex actions
peripheral nervous system
transmits messages via neurons
divided into 2 subsystems/nervous sytems
What are the two divisions of the peripheral nervous system ? (PNS)
The autonomic and somatic nervous systems
Describe the function of the autonomic nervous system (part of PNS)
governs vital functions like breathing, digestion and stress responses
Describe the function of the somatic nervous system (part of PNS)
governs muscle movement and recieves info from sensory receptors
What are the two divisions of the autonomic nervous system? (ANS)
The sympathetic and parasympathetic nervous systems
endocrine system
works along the NS to control vital functions
acts slower than nervous system but is powerful
what do glands do
produce hormones which are secreted in the bloodstream, affecting cells w receptors for it
why do hormones lead to several responses?
they affect more than 1 organ
thyroxine affects heart rate and metabolic rate
what’s the key endocrine gland
pituitary gland
master gland
controls release of hormones
endocrine and ANS working together - what happens when a stressor is perceived
when a stressor is perceived, the hypothalamus activated the pituitary gland which triggers activity in the sympathetic branch of the ANS
the ANS changes from its normal resting state to the sympathetic state
sympathetic nervous system
The sympathetic nervous system is responsible for the body's fight-or-flight response, activating in times of stress or danger. It increases heart rate, dilates airways, and redirects blood flow to muscles.
parasympathetic nervous sytem
Parasympathetic Nervous System
The parasympathetic nervous system is responsible for rest and digest functions in the body, conserving energy and promoting digestion. It works in opposition to the sympathetic nervous system.
adrenaline
released from adrenal medulla
triggers physiological changes which creates physiological arousal necessary fro fight or flight repsonse
immediate and automatic response
starts as soon as threat is detected
(sympathetic) changes in teh body explain why stress, panic or excitement can feel sickly
parasympathetic action
after threat, body returns to PS nervous system returns body to resting state
it acts as a brake and reduces activities of the body that were increased by actions of the sympathetic branch
Describe the role of the parasympathetic nervous system (part of ANS)
decreases fight / flight stress response
reduces:
heart + breathing rate
sweat
narrows pupils
stimulates digestive system
whats rest and digest
Rest and Digest is when the body conserves energy for digestion and recovery, controlled by the parasympathetic nervous system.
What is homeostasis?
when there is a balance between sympathetic & parasympathetic nervous systems, the body is normal and regulated
what is the endocrine system?
a collection of 8 major glands within the body that regulate bodily functions, growth and psychological factors (emotions + behaviour)
what is the role of the pituitary gland within the endocrine system?
located in the brain, the pituitary gland controls the release of hormones from other glands
releases ACTH hormone for fight / flight response
what is the role of the hypothalamus gland within the endocrine system?
located within the brain, the hypothalamus links the nervous system to the endocrine system and maintains homeostasis
releases hormone CRH for fight/ flight response
what is the role of the adrenal glands within the endocrine system?
works to regulate the effect of the fight/ flight response
releases hormones adrenaline and cortisol
what are neurons?
nerve cells which process & transmit information through electrical / chemical signals x
what is the sensory neurons job?
to carry information from the PNS to the CNS
relay neuron’s job
connect sensory neurons to the motor or other relay neurons
motor neurons job
connect the CNS to effectors like muscles and glands
What neurons make up the reflex arc?
sensory neuron , relay neuron & motor neuron
features of a neuron
myelin sheath
nodes of Ranvier
axons
dendrites
terminal buttons
cell body
myelin sheath
nodes of ranvier
Insulating layer around nerve fibers, speeds up signal transmission.
Nodes of Ranvier are gaps in the insulating layer around nerve fibers, known as myelin sheath, which help speed up the transmission of nerve impulses.
axons
dendrites
Axons are long, slender projections of a nerve cell that transmit electrical impulses away from the cell body to other neurons, muscles, or glands.
Dendrites are branch-like extensions of a neuron that receive signals from other neurons and transmit them to the cell body for processing.
terminal buttons
cell body
Terminal buttons are small knobs at the end of axons that release neurotransmitters to communicate with other neurons.
Cell body is the part of a neuron t3hat contains the nucleus and other organelles, responsible for maintaining the cell's functions.
what cell structures does the sensory neuron contain?
sensory receptors
cell body
dendrites
myelin sheath
axon terminals
axon
what cell structures does the relay neuron contain? (located in spine)
dendrites
cell body
axon
axon terminals
myelin sheath
what cell structures does the motor neuron contain?
cell body
dendrites
axon terminals
axon
effector (muscle)
myelin sheath
what are the symptoms of the fight or flight stress response? (ANS)
increased heart + breathing rate
sweating
pupil dilation
digestive system stops
In which order do the reflex arc neurons act?
sensory →relay → motor & brain → reflex movement
explain the reflex arc
sensory neuron detects a sensation, causing an electrical signal to travel through the axon terminal to the relay neuron
relay neuron passes this to the CNS to process it and the motor neuron, causing the affected limb to move
info is sent to the motor neuron before the brain, which is why reflexes are automatic
structure of a the three neurons
long dendrites
short axons
short dendrites
short axons
short dendrites
long axons
location of neurons
sensory neurons are located in the PNS in clusters (ganglia)
motor neurons have long axons, forming part of the PNS
relay neurons are mostly in the brain and visual system
what is a synapse?
a gap between neurons/ the point where one neuron can send a message / communicate to an adjacent neuron
how do neurons communicate
through neural networks
what is synaptic transmission?
the process by which one neuron communicates with another by sending messages across the synapse
what is a neuron?
a nerve cell
what are neurotransmitters?
the body’s chemical messengers that carry info between nerve cells
what are the features of the presynaptic neuron?
direction of action potential
vesicle
axon terminal
transport protein
example of a neurotransmitter
acetylcholine
found at point where a motor neuron meets a muscle and will cause muscles to contract
what are the features of the postsynaptic neuron?
synaptic cleft (in between pre & post)
receptor site
what does the action potential do?
transmits info from one place to another
excitation
when a neurotransmitter increases the positive charge of a postsynaptic and make the post-synaptic cell more likely to fire
inhibition
when a neurotransmitter increases the negative charge of a postsynaptic neuron and make them less likely to fire
how does synaptic transmission actually work?
action potential arrives at axon terminal of presynaptic neuron, causing the vesicles to merge with the membrane of the presynaptic neuron
this releases the neurotransmitters into the synaptic cleft, where the neurotransmitters diffuse across, reaching the postsynaptic cell
what is summation?
the positive/negative effects of the excitatory + inhibitory influences on the post-synaptic cell
what is the process of summation?
excitatory + inhibitory influence are summed
action potential of postsynaptic neuron is only triggered if the sum of the excitatory & inhibitory signals reach a particular threshold - the neuron may or may not fire
define localisation of function within the brain
different regions of the brain are specifically responsible for different behaviours, processes or activities
According to localisation, what happens if an area of the brain gets damaged
The function associated with the aerial will also be damaged
what is the holistic theory
all parts of the brain are involved in the processing of thought and action
hemispheres
Brain is divided into two symmetrical halves
Activity on the left side of the body is controlled by the right hemisphere
Activity on the right side of the body is controlled by the left hemisphere
which areas of the brain are on both hemispheres (sides) of the brain?
motor, somatosensory, visual & auditory
which areas of the brain only appear on the left hemisphere (side) of the brain?
Broca & Wernicke’s area
outline the 4 lobes of the brain
frontal lobe (movement)
temporal lobe (audio)
parietal lobe (sense)
occipital lobe (visual)
outline the 6 localised areas within the brain
motor area
somatosensory
visual area
Wernicke’s area
auditory area
Broca’s area
where is the motor cortex located and what is its function?
frontal lobe
voluntary movement - opp side
damage = loss of control over fine movements
where is the somatosensory cortex located and what is its function?
parietal lobe
processing & receiving sensory info
damage = loss of sensation
amount of som.sen. area devoted to a body part denotes its sensitivity
where is the visual cortex located and what is its function?
occipital lobe
receives & processes visual info
damage to LR hemisphere can cause blindness in the RL field
each eye sends info from visual field to visual cortex
where is the Wernicke’s area located and what is its function?
left temporal lobe
described p with no issue producing language but trouble understanding
damage = speech is fluent but meaningless (Wernike’s aphasia)
where is the auditory area located and what is its function?
temporal lobe
auditory receiving and processing - analyses speech based info
damage = deafness
where is Broca’s area located and what is its function?
left frontal lobe
speech production
damage = difficulty producing fluent speech + slow speech (Broca’s aphasia)
outline Broca’s research into LOF (eval point)
Broca identified an area in the left frontal lobe as responsible for speech production because his patient ‘tan’ ‘s Broca’s area was damaged & could only say the word ‘Tan’
This supports LOF as Broca’s area is specifically on the left hemisphere of the frontal lobe
evaluation on localistaion of function
brain scan support
support for holistic theory
case study
mental disorders
localistion of function - brain scan support
petersen et al. Used brain scones to show wernicke’s area active w listening task and brocas during reading
tulving semantic and episodic mem resides in different parts of the prefrontal cortex
Objective methods for measuring brain activity have provided sound scientific evidence
localistion of function - Lashley
He removed areas of the Cortex in rats that were learning in Maze route
No area was more important than any other area in the ability to learn the route
Therefore learning needs every part of the cortex so processes are not localized but are distribute holistically
Localization of function - Phineas Gage
Metal rod punctured his head and removed most of his front allobe
He survived but his personality changed from calm to quick tempered
It can be hard to make meaningful generalizations from one study and conclusions are subjective
Localisation of function - damage to areas of the brain have been linked to mental disorders
Neurosurgery is a lost resort which targets specific areas which may be involved
Cingulotomy isolates the cigulate gyrus (OCD)
Dougherty et al reported on 44 people with OCD who had undergone a cingulotomy. After 32 weeks almost 30% had met the criteria for successful response to surgery and 14% for partial response
define hemispheric lateralisation
each hemisphere of the brain is specialised to perform different functions
certain mental processes are mainly performed by one hemisphere rather than the other
The visual area in the left and right occipital lobe in the left and right hemisphere - respectively
left and right hemispheres - langauge
Language is lateralised
RH only produces rudimentary was phrases for contributes emotional context to what's said
LH = analyser
RH = synthesiser
ipsilateral
Wiring appears on the same side of the body
vision nad how its wired
Simultaneously contralateral and ipsilateral
Each eye receives light from the left and right visual field
The LVF on both eyes is connected to the RH and the RVF of both eyes is connected to the LH
Visual areas can then compare the slightly different perspective and a depth perception
Similar to auditory input - disparity from the two inputs helps us allocate the social sounds
Split brain research
Connection between the RH and LH is severed - mainly corpus callosum
Used to reduce epilepsy
During a seizure the brain experiences a major electrical Storm which travels between hemispheres and to reduce these fits the connection is cut
Research studies how the hemispheres function when they can't communicate with each other
Sperry procedure
11 split brain individuals were studied with a special setup where an image or word could be predict projected to their RVF and the same or different image would be projected to the LVF
For normal brain the corpus calossum would immediately share the iformation between hemispheres providing a complete picture of the visual world
Presenting the image to one hemisphere meant the info can't be conveyed between hemispheres
Sperry findings
sperry consclusions
Shows how some functions are lateralised and supports the view that LH is verbal and RH is silent but emotional
Connectivity between different regions of the brain is important
what participants did Sperry (1968) use
11 participants who had their corpus callosum cut down the middle (which separates the two hemispheres) in order to treat epilepsy
what was Sperry’s procedure? (1968)
participants were asked to cover one eye & vice versa while shown words / images to describe , assuring that the R and L visual fields were tested
because the ppts hemispheres were severed, the information could not be conveyed to both hemispheres, so the ppts were unable to provide a full understanding
In Sperry’s study, how did the ppts draw the words/images ?
right visual field (left hemis) drew poorly while the left visual field (right hemis) drew clearly
In Sperry’s study, how did the ppts recognise the words/images by touch?
ppts were able to understand and match an object without seeing it to an image with their left hand but could not verbally identify it
(this may be because of language areas being in the left hemisphere)
why are Sperry’s findings difficult to generalise? (eval)
cannot be generalised to wider population because of dispositional ppt factors
small sample, epileptic, undergone drug therapy, varying amnts of corpus callosum cut (therefore ppts brain state varies)
the comparison ‘control group’ were not epileptic which makes them an invalid comparison as epilepsy was not the independent variable being studied
why do Sperry’s findings lack mundane realism? (eval)
Sperry’s experimental procedure was highly artificial because the task did not reflect how ppts would likely process info in day to day life
Also, in real life, both hemispheres would be able to access info simply though the person moving their head
hemispheric lat and split brain research eval
Evidence for lateralization
Evidence against analyzer and sympathiser idea
Recent split brain research
Generalizability problems
hemispheric lat and split brain research - lat. evidence
Fink et al - PET scans to show which areas were active during a visual processing task
When normal participants were asked to attend to larger elements of an image regions of the RH were more active, when required to focus on the finer detail areas of the LH would here as as far as dominate
Hemispheric collection is a feature of the normal brain and the split brain, objective evidence, more validity
hemispheric lat and split brain research - Evidence against analyzer and sympathiser idea
Might be different functions but research shows people don't have a dominant side of the brain which creates a different personality
Nielsen al analysed brain scans (7-29) and from certain hemispheres used for certain tasks but no evidence of a dominant side no artist brain
decreases the validity of the findings of research in hemispheric naturalization
hemispheric lat and split brain research -Recent split brain research
gazzaniga split green participants do better than normal controls and certain tasks. For example they could identify the odd one out and similar objects more than normal controls
Perhaps in the normal brain the LH’s cognitive strategies are watered down by the inferior RH
Supports Sperry that both sides of the brain are distinct and helps it to be more trustworthy by supporting research conducted long ago
hemispheric lat and split brain research - generalisbility
The behaviour of the flip brain group was compared to a neurotypical control group
No participants in control had epilepsy- CV
Differences observe could be due to epilepsy not split brain
Some unique features of the split brains abilities may have been due to the next sea and not split range. Due to this CV you can't generalize the findings for the rest of society
define why the brain is contralateral
each hemisphere of the brain controls the opposite side of the body
left/right right/left
Note
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