SME
Grade 9 Science · Problem type
Membrane potential through an impulse
Use this to record a neuron’s membrane potential through one impulse.
Record and look
0 mV
−55
−70
−70
−55
+30
−40
−80
−75
−70
0 ms
1 ms
2 ms
3 ms
4 ms
5 ms
6 ms
Threshold, −55 mV
Rest, −70 mV
0 ms
1 ms
2 ms
3 ms
4 ms
5 ms
6 ms
Membrane potential (mV)
−70
−55
+30
−40
−80
−75
−70
It passes the threshold and peaks at +30 mV as Na⁺ rushes in; then K⁺ flows out.
It dips to −80 mV, below rest, before the pump restores it.
Tap a bar at the height you want.
Assumptions
•
At rest the inside of a neuron is about −70 mV, more negative than the outside.
•
Past the threshold, about −55 mV, Na⁺ rushes in; then K⁺ flows out and the inside turns negative again.
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