4- Action Potentials and Synapses

Question 1

Intercellular transmission is

Answer 1

Chemical

Question 2

Resting membrane potential

Answer 2

Negative

Question 3

Action potential

Answer 3

Wave of transient depolarisation that travels down the axon

Question 4

Action potential only occurs if

Answer 4

Threshold membrane potential is achieved

Question 5

Absolute refractory period

Answer 5

All sodium channels inactivated

Enforces one way transmission

Question 6

Relative refractory period

Answer 6

Some sodium channels inactivated

Question 7

What does Propagate mean

Answer 7

Transmit

Question 8

Saltatory conduction

Answer 8

Action potentials travelling from one node of ranvier to the next

Question 9

Why are myelinated axons more effective

Answer 9

Fewer ions flow

Less ATP needed to pump them back

Question 10

Temporal summation

Answer 10

Lots of excitatory post synaptic potentials summate over time to reach threshold

Question 11

Spatial summation

Answer 11

Lots of synapses active at the same time- excitatory post synaptic transmissions summate to reach threshold

Question 12

What is the main inhibitory neurotransmitter in the brain

Answer 12

GABA

Question 13

What does GABA do

Answer 13

Opens chloride channels
This allows negative charge
Generates an inhibitory post synaptic potential
This makes it harder to depolarise the membrane
Harder for threshold to be reached so action potential is less likely