Cholinergoc Synapse

Question 1

What is a synapse

Answer 1

The junction between two neurones. Which is able to transmit impulses from one neurone to the other via neurotransmitters

Question 2

What Aare the different types of neurotransmitters

Answer 2

Excitatory neurotransmitter- triggers a new action potential In the post synaptic neurone

Inhibitory neurotransmitter does not trigger a new action potential I.e. GABA.

Question 3

What’s on the presynaptic neurone

Answer 3

Voltage gated calcium ion channels: calcium ion channels will open or close depending on state of polarisation. I.e. if a threshold is reached the channels would open. There lots of calcium ions on the outside of the neurone.

There will also be vesicles inside the PRE SN which contain ACh

Question 4

What’s on the post synaptic neuron

Answer 4

Post synaptic sodium ion channels which can open to allow an influx of sodium ions. These channels also have a receptor site. They are specific to ACh. When ACh binds to the receptors, it causes the sodium ion channels to open

Question 5

How does it work from action potential to transmitting the signal?

Answer 5

Action potential coming in from pre synaptic neurone. This causes depolarisation which means that the calcium ion channels will open. Calcium ions would then rush into the presynaptic neurone down the electrochemical gradient. The calcium will then move the ACh vesicles to the cell surface membrane to fuse with it. This releases the ACh into the synaptic cleft which it will diffuse across to the other end. Where it binds to receptors, binding to the post synaptic sodium ion channels. Hella influx of sodium ions into the post synaptic neurone which causes depolarisation, generating a new action potential

Question 6

What happens to the ACh in the synaptic cleft

Answer 6

It can’t stay there or else there will be a continuous influx of sodium ions and therefore hella action potential. So we break it down via AChE. It is one of the most efficient enzymes in the world and breaks ACh hella quickly into its constituents: choline and acetate. These will diffuse back to the presynaptic neurone. ATP can combine them back into ACh.