Brains, the genome and medicine Flashcards
Explain why the lack of dopamine leads to the symptoms of Parkinson’s diseases
- parkinson’s disease is a brian disorder that affects motor skills
- neurones that control movement are destroyed, these neurones usually produce dopamine, so losing those neurones causes a lack of dopamine
- a lack of dopamine dopamine causes a decrease in transmission of never impulses involved in movement
- synapses are not functioning
Suggest why L-dopa, rather than dopamine, is used for treatment of patients with Parkinson’s disease
- dopamine cannot pass the blood brain barrier
- l-dopa can be absorbed into the brain and converted into dopamine by enzyme dopa-decarboxylase, this increases dopamine levels
- l-dopa is easier/cheap to make
Imaging technique that could be used to establish which parts of the brain have been damaged
- MRI scanning (produces images in finer detail than CT)
- it can produce 3D images
- you could compare image to that of a normal brain
- identify parts of brain and look and shape and size to see if it is abnormal
Explain the effects of nature and nurture on characteristics between identical twins brought up together and identical twins brought up apart
- if there is no difference, it indicates that it is nature
- if there is a difference, mainly due to environment
- multifactorial, polygenic
- examples, e.g. body mass - diet, exercise, intelligence - schooling, parental encouragement
Why the conclusions drawn from data from twin studies should be treated with caution
- small sample size
- different number of twins assessed
- characteristics not measured using comparable units
- difficult to measure intelligence
- no comparison with rest of population
- samples not matched by age, sex, culture, race
Define the term polygenic
- characteristics controlled by more than one gene
If one monozygotic twin has a condition what is the probability of the second twin having the condition, if the condition is entirely caused by genes
- identical twins are genetically identical
- 100%
What could a study show about the roles of genes and the environment of a condition
- genes play a greater role than the environment in developing the condition or vice versa
- genes are inherited
- multifactorial condition, more than one factor causes the condition
- environment has a small effect or vice versa
Why might there be low levels of neurotransmitter
- neurotransmitter is re-uptaken into the presynaptic membrane by the a re-uptake mechanism
How drugs could affect neurotransmitter
- increase transmitter synthesis
- block re-uptake mechanism into presynaptic membrane so more transmitter remains in synaptic cleft
- more transmitter to bind to receptors on post-synaptic membrane
- more APs initiated in postsynaptic membrane
OR - similar shape to transmitter
- binds to receptors on postsynaptic membrane
- APs continually generated
Effects of drugs/toxins on synapses
- prevents neurotransmitter released from presynaptic membrane
- similar shape to transmitter, blocks receptors on postsynaptic membrane
- break down of transmitter
- sodium channels open, permanent depolarisation or hyperpolarisation, continuous AP or no AP
Suggest how Parkinson’s disease can be treated using drugs
- dopamine cannot cross blood brain barrier
- L-dopa is used, which can cross blood brain barrier
- L-dopa is converted into dopamine in the brain
- other drugs could have a similar shape to dopamine and bind to dopamine receptors
other drugs could inhibit enzymes which break down dopamine - maintaining a high concentration of dopamine
Explain why L-dopa is used to treat people with Parkinson’s disease
- L-Dopa can pass blood brian barrier and reach brain
- L-Dopa is converted to dopamine in brain
- increases dopamine levels in the brain
- Parkinson’s disease has low dopamine levels, reduces symptoms of disease
Explain how MDMA (ecstasy) could affect levels of serotonin in the brain
- higher levels of serotonin
- MDMA affects the serotonin synapses in the brain
- MDMA blocks the serotonin re-uptake mechanism
- synaptic cleft flooded with serotonin and cannot be returned to the presynaptic knob
- may reverse pumps to release all the serotonin into the synaptic cleft
- receptors on postsynaptic membrane always filled and floods the brain with impulses
Effects of ecstasy
- increased heart rate
- problems in the body’s thermoregulatory centre
- desire to drink which can lead to hyperthermia (overheating)
- hormone releases to stop kidneys from producing urine
