biopsychopathology Flashcards
what is the nervous system? (2)
- a specialised network of cells in the body and is our primary internal communication system
- it is based on electrical/chemical signals
what are the main two functions of the nervous system?
- to collect, process and respond to info in the environment
- to co-ordinate the workings of different organs and cells in the body
what two subsystems is the nervous system divided into
- central nervous system (CNS)
- peripheral nervous system (PNS)
what is the CNS made up of?
the brain and spinal cord
key info about the brain (4)
- center of all conscious awareness
- cerebral cortex is 3mm thick - only in mammals
- brain is highly developed in humans - distinguishes our higher function
- divided into two hemispheres
key info about the spinal cord (3)
- an extension of the brain
- passes messages to and from the brain and connects nerves to the PNS
- responsible for reflex reactions
what is the role of the PNS (2)
connect the brain and spinal cord to the rest of the body and the external environment. The peripheral nervous system transmits information to and from the CNS through millions of motor and sensory neurons
what is the PNS subdivided into
automatic nervous system - governs vital functions in the body e.g breathing, heart rate, digestion, and stress responses
somatic nervous system - governs muscle movement and receives info from sensory receptors
what is the role of the sympathetic nervous system
sympathetic nervous system - involved with responses that prepare the body for ‘fight of flight’ e.g increases heart rate,blood rate, dilates pupils,
what is the role of the parasympathetic nervous system
parasympathetic system - returns the body to its ‘normal’ resting rate e.g constricts pupils, slows heart rate, stimulates bil release
what is the role of the endocrine system (4)
- a network of glands across the body that secret hormones
- endocrine system works along the CNS
- works slower than the NS but still very effective
- various glands produce hormones which are secreted into the blood stream
what is a gland
an organ that produces and releases substances that perform a specific function in the body.
what is the role of a hormone
chemical messengers that travel in the bloodstream to tissues and organs. Involved with growth, development, metabolism etc
what is the role of the hypothalamus (2)
connected to the pituitary gland and is responsible for stimulating and controlling the release of hormones from the pituitary gland
the hypothalamus is the control which regulates the endocrine system
what is the role of the ‘pituitary gland’ (2)
- ‘master gland’ - hormones released by this gland control/stimulate the release of hormones from other glands in the endocrine system
- divided into the ‘anterior’ (front) and ‘posterior’ (rear) which release different hormones
what is the role of the ‘anterior robe’
anterior robe - releases ACTH which stimulates the adrenal cortex + release of cortisol
what is the role of the ‘posterior robe’
posterior robe - releases oxytocin which is responsible for uterus contractions during childbirth
role of the pineal gland
main hormone is melatonin which is responsible for important biological rhythms including the sleep-wake cycle
role of the thyroid gland
releases thyroxine which is responsible for regulating metabolism
role of the adrenal gland (split into 2 sections)
adrenal medulla - releases adrenaline + noradrenaline which play a role in ‘flight or fight’
adrenal cortex - releases cortisol which stimulates the release of glucose while supervising the immune system
the role of the testes
testes release androgens e.g testosterone
testosterone responsible for the development of male sex characteristics during puberty + muscle growth
the role of the ovaries
release estrogen which controls the female reproductive system
how do the ANS and endocrine systems work together in a ‘fight or flight’ situation (4 steps)
- stressful stimulus the hypothalamus triggers activity in the sympathetic branch of the ANS - ANS changes from resting ‘parasympathetic’ to psychologically aroused state
- adrenaline is released from the adrenal medulla into the bloodstream
- adrenaline triggers physiological changes in target organs in the body and triggers the ‘fight or flight’ response (sympathetic state - dilated pupils, inc heart rate…)
- once threat has passed, the parasympathetic nervous system returns to parasympathetic state + reduces activities of the body
neurons
there are 100 billion neurons in the human nervous system are located in the brain.
by transmitting signals electrically/chemically provide the nervous system with its primary means of communication
what are the 3 types of neurons
sensory neurons, relay neurons, motor neurons
cell body
includes the nucleus (genetic material) of the cell
dendrites
protrude from the cell body, these carry nerve impulses from neighboring neurons towards the cell body
the axon
the axon - carries impulses away from the cell body down the length of the neurons
the myelin sheath
myelin sheath - fatty layer which cover/protects the axon and speeds up electrically transmission of the impulse
nodes of Ranvier
nodes of Ranvier - gaps in the axon - speed up the transmission by forcing it to ‘jump’ across the gaps along the axon
terminal buttons
terminal buttons - at the end of the axon
communicate with the next neurons across the synapse
draw a neuron
draw the endocrine system
location of motor neurons
cell bodies of motor neurons may be in the CNS but they have long axons which form part of the PNS
location of relay neurons
make up 97% of all neurons and most are found in the brain and visual system
location of sensory neurons
are located outside of the CNS, in the PNS in clusters called ganglia
electrical transmission - firing of a neuron (3 steps)
- when neuron is in a resting state, the inside of the cell is negatively charged
- when the neuron is activated by a stimulus, inside of the cell becomes positively charged for a split second causing an action potential to occur
- creates an electrical impulse that travels down the axon towards the end of the axon
chemical transmission
the process of communication between neurons across the synaptic cleft
Neurons communicate with each other within groups known as…
Neurons communicate with each other within groups known as neural networks
Each neuron is separated by…
Each neuron is separated by a synaptic cleft
Signals within neurons are transmitted…
Signals within neurons are transmitted electrically
Signals between neurons are transmitted…
Signals between neurons are transmitted chemically across the synapse
When the electrical signal reaches the end of the neuron (presynaptic terminal) it…
When the electrical signal reaches the end of the neuron (presynaptic terminal) it triggers the release of neurotransmitters from the synaptic vesicles
what are neurotransmitters?
Chemicals that diffuse across the synapse to the next neuron
They are either excitatory or inhibitory
what happens once the neurotransmitter crosses the synaptic cleft? (2)
- taken up by a postsynaptic receptor site on the dendrites of the next neuron
- the chemical message is converted back into an electrical impulse, the message is taken away and the process of transmission starts again in the next neuron
what is the direction of synaptic transmission?
why does is flow this way?
- Direction of travel is one-way
- neurotransmitters are released from the postsynaptic neuron terminal and received by the postsynaptic neuron
each neurotransmitter has its own specific…
Each neurotransmitter has its own specific molecular structure and fits perfectly into the postsynaptic receptor site (lock and key)
neurotransmitters have specialist…
state an example
Neurotransmitters have specialist functions e.g serotonin regulates numerous biological processes including cardiovascular function, bowel motility etc
what happens when an inhibitory neurotransmitter crosses the synapse?
inhibitory neurotransmitters (e.g serotonin) causes inhibition of the post synaptic neuron by causing the neurons to become negatively charged and making it less likely to fire
what happens when an excitatory neurotransmitter crosses the synapse?
excitatory neurotransmitters (e.g testosterone) causes excitation of the post synaptic neuron by increasing its positive charge and making it more likely to fire
Whether a postsynaptic neuron fires is what is decided by the process of…
Whether a postsynaptic neuron fires is what is decided by the process of summation
Whether a postsynaptic neuron fires is what is decided by the process of…
Whether a postsynaptic neuron fires is what is decided by the process of summation
draw a synapse
;p
describe the process of summation
the action potential of the postsynaptic neuron is only triggered if the sum of the excitatory/inhibitory signals at any one time reaches the threshold
- if the net effect on the synaptic neuron is inhibitory then the post-synaptic neuron is less likely to fire. If the net effect is excitatory it is more likely to fire as the inside of the neuron becomes momentarily positively charged - electrical impulse is created + travels down the neuron
describe the six steps of synaptic transmission
- info passed down axon an electrical impulse (action potential)
- action potential reaches end of axon
- action potential reaches the synaptic vesicles (in the end of the neuron)
- Triggers (by opening up the calcium channels) the vesicles to release neurotransmitters into the synaptic cleft (called exocytosis).
- Neurotransmitters then carry the signal across the synaptic cleft binding to the receptor sites on the post-synaptic cell
- The neurotransmitter makes it either more likely/ less likely that the post-synaptic neuron will ‘fire’.
Before the localisation theory, how did people think the brain functioned?
scientists generally supported the holistic theory of the brain - that all parts of the brain were involved in the processing of thought or action
In contrast to the holistic theory, what did Broca and Wernicke argue for?
localisation function (aka cortical specialisation)
what does localisation function argue?
argues that different parts of the brain perfom different tasks and are involved with different parts of the body.
if a certain area of the brain becomes damaged, the function associated with that area will also be affected.
what is lateralisation?
the process by which our physical and psychological functions are dominated by a particular hemisphere
Left-hand side of body controlled by…
Right-hand side of body + language controlled by…
Left-hand side of body controlled by right hemisphere
Right-hand side of body + language controlled by left hemisphere
Cerebral cortex
outer layer of the left and right hemispheres
divided into 4 lobes (frontal, parietal, temporal, occipital)
A lobe
part of an organ that is separate in some way from the rest.
each lobe is associated with different brain functions
Somatosensory area (3)
front of both parital lobes - separated from the motor area by a ‘valley’ called the central sulcus. where sensory info from the skin (touch, heat etc) is represented - amount of somatosensory area devoted to a particular body part denotes its sensititvity e.g for receptors on our face and hands occupy over half the somatosensory area.
Motor area (3)
back of the frontal lobe, in both hemispheres.
Controls voluntary movement on the opposite side of the body.
Damage results in loss of control over fine movements
auditory area (3)
temporal lobes
analyses speech-base info
damage may produce hearing loss
visual area (3)
occipital lobe
each eye sends info from the left/right visual field cortex to right/left hemispheres.
damage to left hemisphere - produces blindness in part of the right visual field of both eyes.
Language is restricted in the _____ for most people.
Language is restricted in the left side for most people.
Broca’s area (2)
Broca identified a small area in the left frontal lobe responsible for speech production
damage to the Broca’s area causes Broca’s aphasia - characterised by slow speech, labourious, and lacking fluency.
Broca’s ‘Tan’ research (4)
Tan could understand spoken language but was unable to produce any coherent words - could only say ‘Tan’
Broca conducted a post-mortem examination - lesion in the left frontal lobe
concluded this area was responsible for speech production
damage to this area - Broca’s aphasia - slow inarticulate speech, difficulty with prepositions and conjunctions
Wernicke’s region (2)
Wernicke identified Wernicke’s region in left temporal lobe as being responsible for language and understanding
damage - Wernicke’s aphasia - produce nonsense words as part of speech
Phineas Gage - research for brain localisation theory (3)
Gage was working as the foreman of a crew preparing a railroad bed - railway incident sending the 43-inch-long through Gage’s left cheek, tearing through his brain
still conscious later that evening and was able to recount the names of his co-workers.
Gage even suggested that he didn’t wish to see his friends since he would be back to work in “a day or two” anyway.
hemispheric lateralisation vs hemispheric localisation
Localisation refers to the fact that some functions, such as vision and language, are governed by specific areas, some localised areas appear in both hemispheres e.g vision
Lateralisation refers to when a functions is only performed by one hemisphere e.g language
why can’t language be performed by both hemispheres?
LH - analyser of language (understanding, production)
RH - synthesiser of language (can only produce rudimentary words/phrases and contributes emotional context)
why is vision not a lateralised function? (3 + image)
Vision - is both contralateral and ipsilateral → each eye receives info from the left visual field (lVF) and right visual field (RVF)
The LVF of both eyes is connected to the RH and the RVF of both eyes is connected to the LH → enables the visual areas to compare slightly different perspectives from each aide and aids depth perception
similar to auditory input - disparity between sounds allows us to locate sounds
why is body movement a lateralised function?(2)
motor and somatosensory areas appear in both hemispheres
motor area of the brain has contralateral wiring - RH controls movements on the left-side of the body
LH controls movements on the left-side of the body
sperry’s split brain research: procedure (4)
- split brain patients - undergone a commissurotomy surgery - separation of hemispheres to treat severe epilepsy
- a word/image is projected to ppt LVF (processed by RH) or the RVF (processed by LH)
- info presented to one hemisphere - not transferred to the other - proves hemispheric lateralisation
- Sperry conducted many different experiments e.g describe what you see, drawing tasks etc
sperry findings: DESCRIBE WHAT YOU SEE TEST
RVF - LH
patient could describe what they saw - superiority of LH in language production
LVF - RH
patient unable to describe what was seen, sometimes reported nothing was present
sperry findings: TACTILE TESTS
objects R HAND - LH
patient could verbally describe what they felt/could identify object in hand by selecting a similar object from a series of alternate objects
L HAND - RH
patients could not describe what they felt - made wild guesses
left hand could identify object by selecting similar object
sperry findings: DRAWING TASKS
RVF - LH
right hand could attempt to draw photos, picture never as clear as left hand - superiority of RH in visual motor tasks
LVF - RH
left hand consistently drew clearer abs better pictures - even if ppt was right-handed - superiority of RH in visual motor tasks
brain plasticity
- brain plasticity- brain’s ability to functionally/physically change and adapt due to new learning experiences
brain plasticity- how does the brain change throughout life? (3)
INFANCY: brain experiences raid growth of synaptic connections
2-3 YEARS: number of synaptic connections peak at approx 15k
ADULT: synaptic connections approx 7k and ‘synaptic pruning occurs’
what is synaptic pruning?
synaptic pruning - when rarely used connections are deleted abs frequently used ones are strengthened
research into brain plasticity - london cabbies procedure (2)
- Eleanor Maguire studied brains of london cabbies
- london cabbies take a training test that assess their recall of of city streets and possible routes - found that this experience alters the structure of drivers’ brains
research into brain plasticity - london cabbies findings (2)
- london cabbies - significantly more grey matter in posterior hippocampus than control group - this area associated with spatial/navigational skills
- longer they had been a cabbie, the more pronounced the structural difference (positive correlation)
research into brain plasticity - medical students procedure (2)
- (supp Maguire research) Dragandki er al
- imaged brains of medical students three months before and a few weeks after a medical exam to see if there were any structural changes
research into brain plasticity - medical students findings (1)
- learning induced changes seen to have covered posterior hippocampus and parietal cortex
what did Gopnik et al say about brain plasticity?
despite people thinking the brain wasn’t able to change, due to lifelong plasticity the brain had the ability to change throughout life
functional recovery (3)
- functional recovery may occur in the brain after trauma - healthy areas of the brain may take over functions of areas that are damaged/missing
- example of neural plasticity
- neuroscientists suggests that this process can occur quickly after trauma and then slow down after several months - at this point patient requires rehabilitating surgery go further their recovery
what happens to the brain during recovery?
dolidage - brain able to rewire and recognise itself by forming new synaptic connections close to the area of damage - secondary neural pathways are activated to enable functioning to continue (often same way as before)
which three processes aid functional recovery?
- axonal sprouting
- denervation supersensitivity
- recruitment of homologous areas
axonal sprouting
growth of new nerve endings which connect with other undamaged nerve cells to form neural pathways
denervation supersensitivity
occurs when axons that do a similar job (to damaged function) are adjusted fo a higher level fo compensate for the ones lost
can have a negative consequence to oversensitivity e.g pain
recruitment of homologous areas
areas on the opposite side of the brain ensure specific tasks are still performed
recruitment of homologous areas - what would happen if the Broca’s area was damaged?
if Broca’s area was damaged (left), right side equivalent would carry out its functions - after a period of time, functionality may then shift back to the left side
