synaptic transmission

Question 1

describe how dopamine acts as a neurotransmitter

Answer 1

dopamine released from pre synaptic membrane into the synaptic cleft
it binds to receptors on the post synaptic membrane
alters the permeability of post synaptic membrane/ causes sodium ion channels to open in the post synaptic membrane
initiates depolarisation/ action potential in the post synaptic neurone

Question 2

describe how low serotonin levels can affect the transmission of impulses in the brain

Answer 2

serotonin is a neurotransmitter
less serotonin results in fewer depolarisations of post synaptic membranes
threshold not achieved/ less chance of action potential being produced in the post synaptic neurone

Question 3

nicotine binds to acetylcholine receptors on the post synaptic membrane of a neurone. explain how nicotine causes an action potential in the post synaptic neurone

Answer 3

nicotine is a similar shape to acetylcholine
increases permeability of membrane to sodium ions/ changes shape of receptors/ channel proteins
nicotine causes the depolarisation of the post synaptic membrane
depolarisation reaches threshold level

Question 4

describe how ions and neurotransmitter molecules are involved in the transmission of an impulse

Answer 4

calcium ions enter presynaptic neurone
so vesicles with neurotransmitter can move towards/ fuse with presynaptic membrane
neurotransmitter molecules diffuse across the synapse
neurotransmitter binds with receptors on post synaptic membrane
sodium ions diffuse into the brain cell/ post synaptic cell, leading to a depolarisation

Question 5

explain why inhibitors of acetylcholinesterase could be useful to stop loss of neurones that produce acetylcholine

Answer 5

acetylcholinesterase breaks down acetylcholine
inhibitors prevents the break down of acetylcholine
so more acetylcholine is available to bind to post synaptic membrane
therefore compensating for the reduced production of acetylcholine/ loss of acetylcholine producing neurones