Question

Neurology questions

Only answer if you have a good knowledge of this.

Answer the 3 following:

1- If in a neuron, E_Na= 40mV and E_k= -80mV, Which of the following has a higher probability of being the E_m value?

a) 40

b) -80

c) -20

d) -70

Explain your answer:

2- On the laboratory about 'the membrane resting potential' two simulations were made. On the first one the internal concentration of potassium was decreased, and in the second one, the external concentration was increased. Which of the following statements describes best what was observed?

a) There was no change in the voltage of the membrane

b) The decrease in the internal concentration of potassium changed the voltage of the membrane and it was less than the change from the increase of the external concentration of potassium

c) The decrease in the internal concentration of potassium changed the voltage of the membrane and it was greater than the change from the increase of the external concentration of potassium

d) In both simulations, the voltage of the membrane was the same

Explain your answer:

3- When working with the action potential, by altering the parameters of the amplitude, we were manipulating:

a) The current

b) The voltage of the membrane

c) The membrane permeability

d) The distribution of ions

Explain your answer:

Answer 1

1)The neuronal membrane is much more permeable to potassium than sodium in the testing state.So Em value will be closer to Ek than ENa.So option A is ruled out.

But it cant be equal to Ek because the membrane is not 100% permeable to potassium .So option B is ruled out.

Out of options C and D; D is much closer to Ek.So answer is option D.

2)The resting membrane potential is calculated by Goldman equation.

In that equation , the concentration of potassium ion outside is in the numerator and that inside the cell is in the denominator .The numerator is smaller and the denominator is larger.So changing the numerator will change the fraction more.

On decreasing the concentration of potassium inside the cell; the change in the membrane potential is less than the change obtained when the outside concentration is increased.So answer is B.

3)By altering the parameters of amplitude , the membrane voltage is changed. So answer is B.