Action potential workshop

Question 1

What is the main difference between voltage activated and ligand activated ion channels?

Answer 1

Voltage activated- activated by a change in the voltage, Na and K activated by less negative/more positive membrane potentials, close when voltage drops or time delay
Ligand activated- need the presence of a ligand i.e. neurotransmitter to open the channel, the channel closes when it diffuses away

Question 2

How can you increase the chance that voltage sensitive ion channels will move to a closed state to be open when the membrane depolarises?

Answer 2

Hyperpolarise the membrane, or make it more negative from where it is

Question 3

What are the mechanisms by which nerves become refractory to stimulation and when approximately is a nerve refractory?

Answer 3

Absolute vs relative refractory periods: absolute is when Na channels are closed or in their inactive state, relative is when the membrane potential is more negative and when it is harder to reach threshold

Question 4

If we have a glutamergic neuron, what is the neurotransmitter within the vesicles?

Answer 4

Glutamate

Question 5

The post synaptic receptor (AMPA receptor) is a ligand sensitive Na/K ion channel, is this an excitatory or inhibitory neurotransmitter and what is likely to happen to the post-synaptic membrane potential?

Answer 5

Excitatory, it would become less negative

Question 6

If the action potential is all or nothing, how can we ensure that the post-synaptic membrane depolarises to threshold?

Answer 6

Repeated action potentials down the one neuron, releasing more neurotransmitter, to open more ligand gated sodium ion channels, to keep depolarising the membrane
Or lots of neurons firing together at the same place on the membrane to depolarise the membrane further

Question 7

What type of ion channel would decrease the likelihood of a neuron producing an action potential? What kind of neurotransmitter might be involved?

Answer 7

Chloride ion channels

Inhibitory neurotransmitter