RMP Flashcards
What is resting memebrane potential
Potential difference/voltage difference of ions in and out of membrane when cell is at rest between ap
What does movement of ions across membrane depend on
Permeability (more to k than Na)
Which gates are closed during RMP
M gate closed
H gate open
K cells naturally leave the cell through which channels down conc gradient (higher conc inside)
Leak K channels
What is movement of ions down conc called
Flux
What opposes conc gradient of k moving out of cell to draw them back in
A -ve charge inside cell (membrane potential)
What is equilibrium potential
Point which no met movement occurs as conc gradient is equal to electrical difference
What is the equilibrium potential for K and na
K = -90
Na = +70
What equation uses temp, gas constant and conc in and out of cell to find equilibrium potential
Nernst
What does larger conc gradient mean in Nernst
Need a bigger electrical difference to reach equilibrium potential
What is the voltage of the resting membrane potential
-80mv
Why is the rmp being -80 indicator of k importance in maintaining it
Close to equilibrium potential of k
Why does K want to move out during resting membrane potential
Rmp is not electrically negative enough to oppose k concentration gradient. Needs to be -90mv. K moves out down conc gradient
Why is rmp less negative than the ep Of k
Because other ions permeability eg ca and cl
What stops k moving out and na moving in down conc gradients to maintain RMP
(Reason why memrbrane isn’t permeable to na)
Na/k ATPase
3 na pumped out
2 k pumped in
Maintains the -80mv
Why is Goldman hodgkin Katz equation better to calculate EP
Because it accounts permeability ration for all ions moving across membrane not just the conc of the k or na
What is low and high levels of electrolyte K called
Hypo and hyperkalaemia
Name 3 ways imbalance of electrolytes occurs
Kidney disfunction
Dehydration (concentrates electrolytes)
Loss of electrolytes via vomit or diarrhoea
How does disrupting K homeostasis affecting cardiac myocytes
Affects electrical activity eg the rmp is affected. This affects ap ability etc
Can lead to issues like tachycardia and ventricular fibrillation/arrhythmia
