A model of an action potential gives these values…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A model of an action potential gives these values. It is a model with stated values and not a recording.
- At ms: mV (rest).
- At ms: mV.
- At ms: mV.
- At ms: mV.
- At ms: mV.
- At ms: mV.
- What is the peak potential?
- By how many millivolts does the potential rise from rest to the peak?
- What is the average rate of rise between ms and ms?
- How far below the resting level does the potential dip at ms?
Need a reminder? The key ideaShow
At rest the membrane is more permeable to K+ than to Na+, and the pump moves out and in. The outside is positive and the inside is negative. A stimulus makes the membrane freely permeable to Na+, the polarity reverses, and this is the action potential. K+ then leaves and the resting potential returns. For one ion, , and at 310 K.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. The table of the model.
Plan. Read the values, then take differences.
Step 1. Peak. The highest value is mV, at ms.
Step 2. Rise from rest. mV.
Step 3. Rate of rise. From mV to mV in ms: mV/ms.
Step 4. The dip. The rest is mV and the dip is mV, so it is mV below rest.
Answer: mV; mV; mV/ms; mV.
Check. The potential at ms is lower than at rest. This is the hyperpolarisation after the spike.
Watch out. Subtracting a negative number adds: .
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