Imbalances in brain chemicals

Question 1

What causes Parkinson’s disease?

Answer 1

The destruction of motor neurones in the brain which control movement and release the neurotransmitter dopamine.

Question 2

What occurs as a result of these neurones being destroyed?

Answer 2

• less dopamine is released into the synaptic clefts, so less receptors bind with dopamine
• postsynaptic neurone is less likely to depolarise as fewer sodium ion channles open
• fewer action potentials are produces

Question 3

What are two symptoms of Parkinson’s?

Answer 3

• slow movement

- tremors

Question 4

What drug has developed to treat Parkinson’s?

Answer 4

L - dopa

• an amino acid which is able to cross the blood-brain barrier (which dopamine cannot cross)
• once it has entered the CNS it is converted into dopamine by the enzyme dopa-decarboxylase
• this increases dopamine levels in the brain and can restore control over movement

Question 5

What causes depression?

Answer 5

• low levels of the neurotransmitter serotonin which transmits nerve impulses across synapses in the part of the brain that control mood

Question 6

What drugs are being developed to combat depression?

Answer 6

• antidepressants to increase levels of serotonin

- selective serotonin reuptake inhibitors (SSRIs) increase serotonin levels by preventing it’s reuptake and synapses.

Question 7

What does ecstasy (MDMA) do?

Answer 7

• inhibiting the reuptake of serotonin into presynaptic neurones by binding to reuptake proteins.
• also triggers the release of serotonin from presynaptic neurones
• this increses serotonin levels and makes them stay high for a long time

Question 8

What are the short term effects of MDMA?

Answer 8

elevated mod

Question 9

What are short term and long term side effecs?

Answer 9

ST = nausea, chills, sweating 
LT = depression, addiction