1.) Assume a neuron has a resting membrane potential of -70 mV and a threshold o
ID: 3507183 • Letter: 1
Question
1.) Assume a neuron has a resting membrane potential of -70 mV and a threshold of -55 mV. There are three synapses active on the neuron each located the same distance from the axon hillock. Which combination of graded potentials will lead to the firing of an action potential? Assume a neuron has a resting membrane potential of -70 mV and a threshold of -55 mV. There are three synapses active on the neuron each located the same distance from the axon hillock. Which combination of graded potentials will lead to the firing of an action potential?
A.) IPSP of -18 mV, EPSP of +6 mV, EPSP of +24 mV
B.) IPSP of -10 mV, IPSP of -2 mV, EPSP of +12 mV
C.) IPSP of -5 mV, EPSP of +10 mV, EPSP of +12 mV
2.) You and your lab partner have prepared a frog nerve for gathering data on action potentials. You connect an electronic stimulator to the nerve and ask your partner to gradually increase the voltage until you see an action potential. Your partner says that the voltage knob is stuck, that is, it will not increase the voltage. Which of the following could trigger an action potential using this stimulator? (select all that apply)
Increase the extracellular concentration of potassium to partially depolarize the neurons Locate the stimulator closer to the trigger zone (axon hillock) Click the stimulate button many times rapidly in successionExplanation / Answer
1.
Action potential is the rapid rise and subsequent fall in the electrical charge across the cellular membrane that causes passage of nerve stimulus. It usually occurs at membrane potential raised upto -55mV (threshold potential).
The potential difference existing just across the cell membrane of resting cell called resting membrane potential. It occurs at -70 mV .
EPSP is the excitatory post synaptic potential, is the electrical charge change in the post synaptic cleft when the excitatory neurotransmitter binds to it. Action potential will be generated when the EPSP raises.
IPSP is the inhibitory post synaptic potential occurs at post synaptic cleft when the inhibitory neurotransmitter binds on post synapse. It occurs when it is more negative.
So that the answer is
C)IPSP of -5mV, EPSP of +10mV, EPSP of +12 mV will generate action potential.
2).
Answer is
Click the stimulator button many times rapidly in succession.
Because rapid and multiple stimulation van initiate action potential.
Other options are wrong because
Increased extracellular volume of K+ will repolarises the membrane potential that doesn't stimulate action potential.
Locating the stimulator closer to the trigger zone without working of probe is useless.
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