Lec 03

Question 1

Icf and Ecf are in

Answer 1

Electrical and chemical disequilibrium
-Many of the solutes in body are ions (have electrical charge on them)
-Unevenly distributed across cell membrane (selective permeability based on ion channels and transporters)

Question 2

Potassium conc in Icf vs Ecd

Answer 2

140 vs 4 mM

Question 3

Sodium conc in Icf vs Ecd

Answer 3

15 vs 145 mM

Question 4

Calcium conc in Icf vs Ecd

Answer 4

0.001 vs 1.8

Question 5

Chloride conc in Icf vs Ecd

Answer 5

4 vs 115 mM

Question 6

Most important reason of K disequilibrium

Answer 6

Potassium leak channels

Question 7

Resting Membrane Potential

Answer 7

Net charge of ICF and ECF at rest
Result of unequal distribution of ions
All living cells have resting membrane potential
RMP IS USUALLY NEGATIVE
most important factor: K LEAK CHANNELS

Question 8

Measuring potential difference

Answer 8

Outside is set to 0
Inside cell relative to outside is measured

Question 9

Equilibrium potential

Answer 9

Electrical gradient exactly opposes concentration gradient so there is no net movement of ions

Question 10

Permeable ions will move down the electrochemical gradient until ———

Answer 10

V(m)=E(x)
Equilibrium

Question 11

Nernst Equation definition

Answer 11

If membrane was only permeable to one type of ion, membrane potential would be equal to nernst equation

Question 12

Nernst Equation

Answer 12

E(ion)=61/z*log(ion(out)/ion(in))

Question 13

Potassium ion electrochemical gradient

Answer 13

1- K concentration gradient drives k out of the cell
2- excess negative charge pulls k back

Question 14

If E(k) is 80mv and V(m)=-120mv

Answer 14

Stronger electrical gradient
Greater tendency of potassium to stay in
NET INWARD FLOW

Question 15

If E(k) is 80mv and V(m)=-94mv

Answer 15

Equilibrium potential
NO NET ION FLOW

Question 16

If E(k) is 80mv and V(m)=-80mv

Answer 16

Stronger chemical gradient
Greater potassium tendency to leave
NET OUTWARD FLOW

Question 17

GHK equation definition

Answer 17

Predict membrane potential that results from contribution of all ions across membrane

Question 18

GHK equation two factors

Answer 18

1- concentration gradient
2- relative membrane permeability

Question 19

Resting membrane is close to E(k)

Answer 19

1- cells are 40 times more permeable to k than Na
2- k leak channels
3- K is primary contributor to RMP

Question 20

K eq potential

Answer 20

-90 mV

Question 21

Primary modulator of ion permeability

Answer 21

Ion channels

Question 22

V(m)=-80mV why?

Answer 22

1- k leak channels
2- na/k pump
3- negative charge phosphate and protein

Question 23

When potential is getiing more negative

Answer 23

Hyper polarization

Question 24

Membrane potential is getting more positive

Answer 24

Depolarization