Transmission of impulses across synapses

Question 1

Outline the process that occurs for the transmission of impulses across a synapse to occur

(8 stages)

Answer 1

1) Action potential reaches the end of the presynaptic neurone
2) Depolarisation of the presynaptic membrane causes calcium ion channels to open
3) Calcium ions diffuse into the presynaptic knob

4) This causes synaptic vesicles containing neurotransmitters to fuse with the presynaptic membrane
- Neurotransmitters are released into the synaptic cleft via exocytosis

5) Neurotransmitter diffuses across the synaptic cleft and binds with it’s specific receptor molecule on the postsynaptic membrane
6) This causes sodium ion channels to open
7) Sodium ions diffuse into the postsynaptic neurone
8) This triggers an action potential and the impulse is propagated along the postsynaptic neurone

Question 2

What enzymes break down acetylcholine?

Answer 2

Acetylcholinesterase

Question 3

What are the products fro the hydrolysis of acetylcholine?

Answer 3

Choline

Ethanoic acid