Synapses

Question 1

What is a synapse?

Answer 1

gap between 2 neurones

Question 2

How is the action potential transmitted across a synapse?

Answer 2

neurotransmitters diffuse, bind and trigger an action potential in the next neuron

Question 3

What happens when an action potential reaches the synaptic knob? (in a cholinergic synapse)

Answer 3

depolarisation causes the voltage-gated Ca2+ channels open, and ions diffuse in to the synapse

Question 4

What do the Ca2+ ions cause to happen?

Answer 4

vesicles containing neurotransmitters bind to the pre-synaptic membrane and release the neurotransmitters into the pre-synaptic cleft

Question 5

What do the neurotransmitters do?

Answer 5

diffuse across the synapse, towards to post-synaptic neurone

Question 6

What happens when neurotransmitter reach the post-synaptic neurone?

Answer 6

they bind to complementary receptors in the membrane of the post-synaptic neurone

Question 7

Why does the impulse only travel in one direction?

Answer 7

• vesicles only found in pre-synaptic neurone
• receptors only found in membrane of post-synaptic neurone

Question 8

What happens when neurotransmitters bind to the post-synaptic membrane?

Answer 8

Na+ channels open/widen and Na+ diffuses into the neurone, causes the post-synaptic neurone to become depolarised

Question 9

What happens after the action potential has been triggered?

Answer 9

neurotransmitter is degraded and released from the receptor, the Na+ channels close and resting potential is established

Question 10

What happens to the neurotransmitters when they are released from the post-synaptic membrane?

Answer 10

they are transported back into the pre-synaptic membrane and are recycled

Question 11

What is the name of the neurotransmitter in a cholinergic synapse?

Answer 11

Acetylcholine

Question 12

What enzyme can break down Acetylcholine?

Answer 12

acetylcholine esterase

Question 13

What is acetylcholine broken down into?

Answer 13

acetate and choline