Ions, Permeability and the Resting Potential

Question 1

What is the resting membrane potential?

Answer 1

-70mV so the cell membrane must be more permeable to potassium than sodium

Question 2

What happens is the potassium permeability increased by a factor of 50?

Answer 2

As there is a greater influx of potassium out of the cell, there is a greater negative charge within meaning the cell would hyperpolarize

Question 3

What happens if the sodium permeability increased by a factor of 100?

Answer 3

A greater influx of sodium inside taking more positive charge meaning it will depolarise

Question 4

What is the threshold potential?

Answer 4

The potential that must be reached to trigger an action potential

Question 5

What happens when the cell reaches the threshold potential?

Answer 5

All the sodium voltage gated channels open creating a rapid depolarisation

Question 6

What happens when the membrane potential reaches maximum voltage?

Answer 6

Sodium voltage gated ion channels close and potassium voltage gated ion channels open, hyperpolarising the cell membrane

Question 7

What is the effect of giving someone a litre of sodium saline and potassium saline?

Answer 7

No increase in membrane potential- sodium

Increase in membrane potential by 5 fold- potassium