I have 4 question (not homework)
What happens to the cells membrane potential if:
a) Na+ outside rises by 40mM
b) K+ inside rises by 10mM
c) K+ outside rises by 10mM
d) A- (impermeable ion) inside rises by 100mM
e) Na+ outside decline by 50mM
So my answers are:
a – hyperpolarisering (more negative)
b – Depolarisering (more positive)
c – Hyperpolarisering
d – Depolarisering
e - Depolarisering
I think it like this:
Membrane potential is the DIFFERENCE in electrical potential inside and outside the cell. When we say a cell has a resting potential of -60mV we mean that the cell has 60mV LESS than the extracellular space.
So when I am asked what happens if all of a sudden, the extracellular space increases in mV (first question) then I can say that the difference is now GREATER than 60 mV, it is now in fact 100 mV, as the extracellular space has increased by 40 mV, then plussing the already established 60 mV.
Is this the correct way to think about these problems?