8 - DRUGS AND DISEASE Flashcards
What are neurotransmitters and how do they link to disorders?
Neurotransmitters are chemicals that transmit nerve impulses across synapses. Some disorders are linked to an imbalance of specific neurotransmitters.
What two diseases are caused by this kind of imbalance?
Parkisons and Depression
What is Parkisons disease?
Parkisons disease is a brain disorder that affects the motor skills of people
Why does it occur?
It occurs because neurones in parts of the brain that control movement are destroyed.
What do these neurones normally do and what does the fact they are destroyed mean?
They normally produce the neurotransmitter dopamine, so losing them causes a lack of dopamine.
What does this mean?
1) This means that less dopamine is released into the synaptic clefts, so less dopamine is available to bind to the receptors on the postsynaptic membrane.
2) Fewer sodium ion channels on the postsynaptic membrane open, so the postsynaptic cell is likely to depolarise
3) This means fewer action potentials are produced, leading to symptoms like tremors
What are people with Parkisons given?
L dopa
What is L dopa?
A drug that is similar to dopamine, but unlike dopamine can be absorbed into the brain, and then converted into dopamine by the enzyme dopa-decarboxylase
What does taking L dopa mean in terms of the brain?
A higher level of dopamine is given to the brain, and more impulses are transmitted across synapses in the parts of the brain that control movement
What is the thought cause of depression?
A lack of the neurotransmitter serotonin
What does serotonin do?
Transmits nerve impulses across synapses in the parts of the brain that control mood.
What is given to people with depression?
MDMA (ecstasy)
What does MDMA do?
Increases the level of serotonin in the brain
How does MDMA increase the level of serotonin?
By increasing the level of serotonin in the brain by inhibiting the reuptake of serotonin into the presynaptic neurone - it binds to and blocks the reuptake proteins on the postsynaptic membrane.
What else does MDMA do?
It triggers the release of serotonin from presynaptic neurones, meaning that serotonin levels stay high in the synapse and cause depolarisation of the postsynaptic neurones in parts of the brain that control mood.
