4. Synaptic Transmission AO1

Question 1

What is a synapse?

Answer 1

Each neuron is separated from the next by a tiny gap called the synapse

Question 2

How are signals within neurons transmitted?

Answer 2

Electrically

Question 3

How are signals between neurons transmitted?

Answer 3

Chemically across the synapse

Question 4

What happens when the electrical impulse reaches the end of a neuron?

Answer 4

It triggers the release of neurotransmitter from tiny sacs called synaptic vesicles

Question 5

What happens after the release of the neurotransmitter?

Answer 5

It crosses the gap, it is taken up by the postsynaptic receptor site in the next neuron

Question 6

What happens after neurotransmitter is taken up by the postsynaptic receptor site?

Answer 6

Chemical message is converted back into an electrical impulse and the process of electric transmission begins

Question 7

What are neurotransmitters?

Answer 7

Chemicals that diffuse across the synapse to the next neuron in the chain

Question 8

Outline a neurotransmitter

Answer 8

Several dozen have been identified, each has its own specific molecular structure that fits perfectly into a postsynaptic take receptor site (lock and key) - each has a specific function

Question 9

Give an example of a neurotransmitter and explain its role

Answer 9

Serotonin - affects mood and social behaviour which is why it has been implicated as a cause of depression

Question 10

What do neurotransmitters usually have?

Answer 10

Excitatory or inhibitory effects on the neighboring neuron

Question 11

Explain adrenaline in regard to being excitatory or inhibitory

Answer 11

Generally excitatory, increasing positive charge of the postsynaptic neuron, making it more likely the neuron will fire

Question 12

Explain serotonin in regard to being excitatory or inhibitory

Answer 12

Generally inhibitory, increasing the negative charge of the postsynaptic neuron, making it less likely the neuron will fire

Question 13

Explain dopamine in regard to being excitatory or inhibitory

Answer 13

It is an unusual neurotransmitter is it is equally likely to have excitatory or inhibitory effects on the next neuron in the chain

Question 14

Explain summation

Answer 14

Excitatory and inhibitory influences are summed and must reach certain threshold for action potential of postsynaptic neuron to be triggered

Question 15

When is a postsynaptic neuron less likely to fire

Answer 15

If the net effect of neurotransmitter is inhibitory

Question 16

When is a postsynaptic neuron more likely to fire

Answer 16

If the net effect of neurotransmitter is excitatory