Bioelectricity

Question 1

What is membrane potential critical for

Answer 1

cell function

Question 2

True or False - ALL cells have membrane potentials

Answer 2

TRUE

Question 3

How do you measure membrane potential

Answer 3

Impail the cm into the intracellular fluid compartment with glass electrode, measure in respect to 0mV fluid

Question 4

What determines membrane potential

Answer 4

unequal distribution and selective movement of ions

Question 5

What does Vm stand for

Answer 5

membrane potential

Question 6

What transporter maintains normal cell membrane potential / environment

Answer 6

Sodium potassium ATPase

Question 7

What is the contribution of the sodium potassium ATPase to the resting membrane potential

Answer 7

contributes 20% directly

Question 8

How does sodium potassium ATPase contribute to the resting membrane potential.

Answer 8

Na+/K+ ATPase carries one positive charge out of the cell

Question 9

What is the effect of the Na+/K+ ATPase carrying one positive charge out of the cell

Answer 9

leaves a negative charge inside the cell, this maintains the driving force

Question 10

Describe the concentration gradient for potassium movement in relation to the cell

Answer 10

concentration gradient for potassium to move out of the cell

Question 11

What is the effect of potassium moving out of the cell

Answer 11

inside of the cell becomes more negative

Question 12

What ions cannot cross the cell membrane

Answer 12

anions

Question 13

Why is it important that anions cannot cross the cell membrane

Answer 13

allows cell to generate negative membrane potential

Question 14

What is the current when there is no NET movement of potassium

Answer 14

0 current

Question 15

What is the potential called when there is no NET movement

Answer 15

Nernst potential

Question 16

What is the effect of ion movement on membrane potential

Answer 16

move the membrane potential towards their Nernst potential

Question 17

What does it mean if a cells membrane potential is -70mV

Answer 17

potassium channels are working and functional

Question 18

Why is the cells membrane potential slightly more positive than the Nernst potential for potassium

Answer 18

Sodium channels can be slightly leaky

Question 19

Describe the concentration gradient for sodium movement

Answer 19

sodium moves into the cell down its conc gradient

Question 20

What is the effect of sodium influx on the cell potential

Answer 20

makes the membrane potential more positive

Question 21

What is the Nernst potential for sodium

Answer 21

+61.5

Question 22

What is the effect of sodium channels opening on the membrane potential

Answer 22

shift the membrane potential towards the Nernst potential for sodium

Question 23

What does the Goldman equation calculate

Answer 23

Membrane potential

Question 24

What does the Goldman equation give us information about

Answer 24

membrane permeability

Question 25

What would the cells membrane potential be if only sodium channels were open

Answer 25

+60mV

Question 26

Why does the influx of sodium generate an action potential

Answer 26

when voltage gated sodium channels open the influx of sodium drives the membrane potential towards its Nernst potential - positive

Question 27

Describe the repolarisation phase of the action potential with reference to potassium and their Nernst potential

Answer 27

at the peak of the action potential, potassium channels open and drive the membrane potential towards its Nernst potential - negative

Question 28

What is different about Na+ amino acid co transport in the epithelial cell with reference to the membrane potential

Answer 28

Repolarisation occurs when potassium channels open however this is more gradual and the co transporter remains open