Biological Flashcards
Which 2 parts make up the central nervous system?
Spinal cord and Brain
What are the 2 halves of the brain called?
hemispheres
What does the brain do?
coordination centre of sensation and intellectual and nervous activity
What does the spinal cord do?
reflex actions -links the brain to the rest of the body (peripheral NS)
Define ‘contralateral’
Left side of the brain controls right side of the body and vice versa
What is the cerebral cortex?
outer layer of the brain
What are convolutions?
folds on the cerebral surface (wrinkly)
What are gyri and sulci?
ridges and valleys in the cerebral cortex
What is lateralisation?
different functions for each hemisphere of the brain
What is localisation?
within a hemisphere, certain behaviors are localized to one specific area
What is the function of the frontal lobe?
-controls high level thinking, planning and problem solving -contains motor cortex -contains Broca’s area -one in each hemisphere
What is the motor cortex?
strip along the top of the brain
What does Broca’s area do?
left frontal lobe responsible for speech production
What does the parietal lobe contain?
somatosensory cortex
What does the somatosensory cortex do?
processes sensory information from the skin -touch, temperature and pressure -contralateral
What does the temporal lobe do?
contains auditory cortex (which is contralateral) -processes location, volume and pitch of sounds -role in language
What does Wernicke’s area do and where is it located?
left temporal lobe -understanding of languages
What is the occipital lobe responsible for?
contains primary visual cortex -contralateral
What does the visual cortex do?
interprets messages from our eyes into images we can understand
What is the corpus callosum?
link of fine fibres which connect the hemispheres together -shares info between hemispheres
What does the Thalamus do?
brain relay station
-receives info from senses
What does the Hypothalamus do?
controls motivational behaviors (hunger, thirst, sex drive) -stress response -maintains balance in functions (body temp, hormones)
What is the limbic system responsible for?
contains several structures -regulates emotional response
What does the cerebellum do?
coordinates posture, balance and movement -receives and integrates info from spinal cord + other areas
What are the parts of the Nervous system?
- peripheral or central NS
- autonomic or somatic NS
-CNS - brain and spinal cord - sympathetic and parasympathetic NS
What is the sympathetic NS responsible for?
preparing the body for fight or flight
What does the parasympathetic NS do?
returns the body to its normal state after fight or flight
What does the autonomic NS do?
-controls body’s involuntary movements -controls the organs of the body
What does the somatic NS do?
-controls body’s voluntary movement -transmits signals to and from senses and muscles
What is the peripheral NS?
all of the NS outside CNS
What is the nervous system?
The network of nerve cells and fibres which transmits nerve impulses between parts of the body
What are the 3 types of neuron?
Sensory, relay and motor
What does the sensory neuron do?
receives messages from receptors -travels along nerves in the peripheral NS to the CNS -has long dendrites and short axons
What does the motor neuron do?
carries messages from the CNS to effectors -along nerves in the peripheral NS -short dendrites and long axons
What does the relay neuron do?
connects sensory and motor neurons -only found in CNS -short dendrites and short axons
What are neurotransmitters?
chemical messages between neurons in the brain -allows brain to process thoughts and memories -each NT has particular function (excitatory or inhibitory)
Explain the 7 stages of Synaptic Transmission.
1: nerve impulse travels down an axon 2: nerve impulse reaches synaptic terminal 3: triggers the release of neurotransmitters 4: neurotransmitters fired into synaptic gap 5: neurotransmitters bind to receptors on the dendrite of adjacent neuron 6: if successfully transmitted, NT taken up by post-synaptic neuron 7: message will continue to be passed on via electrical impulses
What is an agonist drug?
-imitates natural neurotransmitters -fools the brain into activating pleasure centres -much more powerful than natural occurring NT’s
What is an antagonist drug?
boosts amount of normal neurotransmitters -triggers brain pleasure centre
Which 2 recreational drugs does the course focus on?
cocaine and heroin
How does cocaine impact the role of dopamine?
blocks reuptake of dopamine by binding with dopamine transporter molecules on terminal buttons of presynaptic neuron -synapse flooded with surplus of dopamine
What are effects of cocaine?
stimulant effect on the cns
dopamine receptors become downregulated -fewer receptors active, some damaged and shut down -quantity of dopamine produced decreases -tolerance increases, withdrawal, cravings
What are the effects of heroin?
depressant effect on CNS -processed into morphine, which binds with specific receptor
neural transmission = down regulation -receptors desensitized, tolerance increases
What is a strength of recreational drug research.
there support for the effect on dopamine from research using non-human animals. That is a common procedure involving mice (previously exposed to cocaine use) which deliberately damages the mesocorticolimbic pathways in the brain so the neurons cannot produce levels of dopamine normally associated with reward. After this procedure the mice did not feel the need to take the cocaine, as a control they perform lesions on other areas of the brain but they do not find that this failure to self administer occurs when this happens. The supports the view that cocaines affects are due to the activity of dopamine in the brain’s reward system
What is a weakness of recreational drug research?
It is based off animal research, transmission processes in mammals are similar but there are differences because the human brain is more complex than the mouse brain so isolating the effects of just one neurotransmitter oversimplifies the process so therefore can be reductionistic (ignoring the effects of serotonin or noadrenaline) and ungeneralisable (animals to humans)
What is a counter argument to the weakness of recreational drug research?
Evidence of drug effects on the CNS transmission also comes from studies of humans. Volkow et al 1997 used pet scans to track activity of dopamine transporters during a cocaine induced high, And found that the extent to which cocaine occupied dopamine transporters correlated positively with the course of the subjective experience, supporting the view that evidence from animal models is in fact valid as human studies produce similar results
What is an application of recreational drug research?
It can help lead to better addiction treatments, for example heroin was identified as an agonist that binds to opiate receptors, Therefore by the addict having treatments such as naloxone, an antagonist that blocks these receptors, The reward of euphoria isn’t achieved when taking heroin so the user then stops
What does the amygdala do?
controls emotion responses (particularly fear)
What does the hippocampus do?
encodes long term memories
What would happen if the prefrontal cortex was damaged? (Raine et al)
person would seek immediate gratification -more negative emotions
What are the 3 types of brain scan?
CAT, PET and fMRI
Outline how CAT scans work
xrays -detailed cross-section images of inside of body
Outline 2 advantages of CAT scans.
useful for revealing abnormal structures -high resolution, good quality images
outline 2 disadvantages of CAT scans
high levels of radiation -only provide structural info (still images)
Outline how PET scans work
measure metabolic activity in brain -radioactive glucose substance injected (radiotracer)
colour scale of activity, red/ orange is most active blue/ purple is least
outline 2 advantages of PET scans
shows brain in action -provide evidence of localisation of functions
outline 2 disadvantages of PET scans
results sometimes not easy to interpret -ethical issues, radioactive substances can damage tissues
outline how fMRI scans work.
-uses radiowaves to measure blood oxygen levels in brain -blood directed to active areas -picked up through radio signals which produce 3D images