L6 Graded Potentials

Question 1

Which of the following could produce an inhibitory post synaptic potential?

Opening Na+ channels

Opening K+ Channels

Opening Cl- channels

Answer 1

Opening K+ and Cl- channels will both make the cell more negative

(Remember K+ equilibrium potential is -90 and also remember that Cl- is higher outside so if you start letting that in, it will also make it more negative)

Question 2

What is the voltage of a typical EPSP?

Answer 2

0.5 mV

Question 3

How many mV does a typical neuron need to reach threshold?

Answer 3

15 mV

We’re just going from -70 to -55 it’s not that hard

Question 4

How many EPSPs does the typical neuron need to reach threshold?

Answer 4

30 EPSPs

Each EPSP is about 0.5 mV and we need 15 mV to get from -70 to -55

Question 5

What is temporal summation?

Answer 5

A single synapse receiving many EPSPs in a short period of time (from the same presynaptic cell)

Question 6

What is spatial summation?

Answer 6

A single synapse receiving many EPSPs from multiple presynaptic cells

Question 7

What part of the neuron needs to reach threshold in order for the action potential to take place?

Answer 7

Axon hillock