L5 Resting Membran Potential

Question 1

Do all living cells have some resting potential?

Answer 1

Yes

Question 2

What’s the membrane potential present in cells of non-excitable tissues?

Answer 2

A constant

Question 3

What’s resting potential ?

Answer 3

Difference that exists across the membrane of excitable cells at a steady state

Question 4

What are the two excitable tissues?

Answer 4

Muscles and nerves

Question 5

What’s the resting membrane potential of a neuron?

Answer 5

-70mV

Question 6

What’s the resting membrane potential of a muscle cell?

Answer 6

-90mV

Question 7

Which ion has a greater influence on RMP?

Answer 7

K+ because higher conductance at rest

Question 8

Ohms law/Goldman equation

Answer 8

Estimates membrane potential knowing equilibrium potentials and conductances for each ionic species in a question

Em= (gkEk + gNaENa + gClECl + gCaECa) /(gK+gNa+gCl+gCa)

g = conductance
E depends only on conc gradient of ion out and ion in

Question 9

Conductance changes as

Answer 9

More channels open

Question 10

Short version of ohms law/ Goldman equation

Answer 10

Em= (gKEk+gNaENa)(gK+gNa)

Question 11

If K + channels suddenly open with no concentration gradients or other property changes what happens to E memb?

Answer 11

gK goes up

And therefore Ememb gets more neg

Now cell is hyperpolarized

Question 12

Hypokalemic means

Answer 12

Lower K+ in ECF than normal

Question 13

Hyperkalemic means

Answer 13

Higher K+ in ECF than normal

Question 14

What happens to a severely hypokalemic patients RMP?

Answer 14

Hyperpolarized RMP

gets more negative

Further away from where it needs to get to be able to activate

Question 15

What happens if a muscle becomes hyperpolarized?

Answer 15

They can’t contract properly

Can lead to paralysis, suffocation, asystole

Question 16

What happens to a severely hyperkalemic patients RMP?

Answer 16

Depolarized RMP

Gets more positive

Fire more often that normal

Question 17

What happens if a neuron RMP becomes depolarized?

Answer 17

They fire more often

Tingling sensation
Muscle twitch
Bradycardia or arrhythmia

Severe hyperkalemic can lead to paralysis as the neurons and muscles enter into a state where they cannot reset or fire again

Question 18

Na+-K+ATPase transfers what?

Answer 18

3 Na + out
2 K+ in

Contributes only 5-20mV to RMP

Diffusion of ions down conc gradient is the primary mechanism that maintains RMP

Question 19

Overall the sodium potassium pump doesn’t contribute to RMP

Answer 19

It just maintains it

Most membrane potential is caused by the diffusion of sodium and potassium down conc gradients though backgrounders channels

Question 20

Increase ECF K+ or Na+ both lead to

Answer 20

Depolarization of RMP

Question 21

Decreased ECF K+ or Na+ lead to

Answer 21

Hyperpolziaton of RMP

Question 22

At rest, there’s a high permeability to

Answer 22

Potassium