2. Synaptic Transmission

Question 1

1 Where does an action potential arrive?

Answer 1

At the synaptic knob of the presynaptic neurone.

Question 2

2 When the action potential arrives, what does it stimulate?

Answer 2

Voltage gated calcium ion channels open in the presynaptic neurone.

Question 3

3. What happens when the voltage gated calcium ion channels open?

Answer 3

The calcium ions diffuse into synaptic knob.

They are then pumped out afterwards by active transport.

Question 4

4. What does the influx of calcium ions into synaptic knob cause?

Answer 4

The synaptic vesicles within the synaptic knob fuse with presynaptic membrane.

Question 5

5. After the synaptic vesicles have fused with presynaptic knob, what happens?

Answer 5

The vesicles release neurotransmitter acetlycholine into synaptic cleft by exocytosis.

Question 6

6. What happens when the synaptic vesicles diffuse into synpatic cleft?

Answer 6

They bind to specific cholingeric receptors on postsynaptic membrane.

Question 7

7. What happens when they bind to specific cholingeric receptors on postsynaptic membrane?

Answer 7

Causes sodium ion channels on the postsynaptic neurone to open. This influx of sodium ions causes depolarisation to occur.

Question 8

8. When is an action potential of the post synaptic membrane generated?

Answer 8

If the threshold is reached.

Question 9

9. What happens when acetlycholine is moved from synaptic cleft?

Answer 9

The response won’ keep happening.

As Its broken down by enzyme called acetlycholinesterase.

Question 10

10. What happens when acetlycholine is broken down by enzyme called acetlycholinesterase?

Answer 10

The products are reabsorbed by the presynaptic neurone used to make more ACh.

Question 11

What does exocytosis mean?

Answer 11

Process by which a vesicle inside a cell moves to cell surface membrane and fuses with membrane releasing its cell components outside of cell.