Question

"A student new to neuroscience research made extracellular solution and is practicing recording resting membrane potentials from giant squid axons. During one of the trials, the resting membrane potential, which is normally around - 60 mV, measured -15 mV. What potential mistake might the student have made in measuring components for the extracellular solution to cause such a change?"

- This should be in a paragraph answer

- it has something to do with not being permeable enough to Na+, and too much K+ being on the outside.

- I had originally put a paragraph along the lines of putting more Na in the cell instead of having more Na outside the cell like normally, but only got 2/6 points.

Answer 1

Firstly let me appreciate to you for framing the question well.

so basically,in normal condition the Na + charge is more on outside and charge inside is less ,vise versa for K+.In normal condition there is a potential difference for both sodium and potassium .Na+ moves into cell and K+ moves outside cell.

All of this will lead to a net negative resting membrane potential that is here -60mv(usually for neuron)(its differnet for different cell in body)

Here in this example

The extracellular solution is not the normal body extracellular fluid ,it is artificially made and he commits a mistake ,our aim is to figure out this mistake.

In question instead of -60mv the resting potential is -15mv,so two possibilities are there

1)either the Na+ is more in the extracellular fluid which leads to its influx into cell leading to a less negative value -15mv(what you wrote i i gues but its not very correct

2)next is if more K+ is outside cell then it will lead to less efflux of K+ out of cell hence lead to more accumulation of positive charge inside hence -15 mv

If you have anymore queries please feel free to ask