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Flashcards in Resting membrane potential Deck (28)
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1

What is the resting membrane potential?

The potential difference (mv) between the inside and outside of a cell at rest

2

What is the value of the resting membrane potential?

-30mv and -90mv always polarised

3

What is the average RMP for a neurone?

~-70mv

4

What is the average RMP for a skeletal muscle cell?

~-90mv

5

What ion are cells most permeable to at rest?

Potassium

6

What leads to potassium loss from a cell?

High concentration gradient within the cell, diffusion of K+ out down conc grad.

7

What pulls potassium into the cell?

Loss of +ve charge from cell as K+ moves down its concentration gradient creates and electrical pull into the cell

8

If membrane just permeable to potassium at what point is there no net flux?

Flux driven by chemical gradient = flux driven by electrical gradient
-90mv

9

What is equilibrium potential for potassium?

-90mV

10

What is equilibrium potential?

Potential at which flux driven by chemical = flux driven by electrical gradient

11

What is ENa?

+58mV

12

Why is Em closer to Ek?

Cell at rest more permeable to potassium

13

What is meant by the Nernst equation?

Gives the ion equilibrium potential

14

What are components of Nernst equation?

Gas constant
Temp
Farradays constant
Valency
Concentration of ion in and out of the cell

15

What does Na+K+ Pump do?

Uses ATP hydrolysis to pump 3NA+ out and 2 K+ in

16

Why is Na+K+ important?

Ion gradient created allows ion movement to establish membrane potential

17

What is the downfall of Nernst in estimating a cells Em?

Does not take into consideration concentrations and permeability of other ions

18

What equation is better at estimating Em than Nernst?

Goldmann-Hodgkin-Catz

19

Describe kinetics relationship between Na+ concentration and Na+ efflux from pump

Sigmoidal

20

What is the effect of increased extracellular K+?

Reduces outward gradient so Em less negative and membrane repolarised

21

What is effect of more external Na+ on Em?

Increased diffusion into cell depolarisation

22

What is the effect of increased Cl- extracellularly on Em?

Concentration gradient to drive Cl- into cell so hyperpolarise membrane

23

What is meant by the valence of an ion (Z) in Nernst?

Ion charge

Cl-= -1
Na+=+1

24

When and ion is in steady state what can be said about ratio of +ve to -ve ions on inside and outside of cell?

Equal numbers

25

Raising the extracellular K+ concentration bathing a nerve cell would

Make Ek less negative (more positive)

26

Reducing the extracellular concentration of Na+ ions would

Make ENa more negative (less positive)

27

A doubling of the intracellular Na+ ion concentration will

Stimulate membrane ion transport by Na+/K+ ATPase proteins

28

A change of extracellular K+ ion concentration to 2.0 mM will

Decrease membrane ion transport by Na+/K+ ATPase proteins.