Physiology: Na/K/ATPase pump & action potential

Question 1

what is the net movement of Na and K from the Na/K/ATPase pump

Answer 1

3 Na out

2 K in

Question 2

what is the first step of the Na/K/ATPase pump

Answer 2

3 Na from inside cell bind to the carrier pump protein

Question 3

what is the second step of the Na/K/ATPase pump

Answer 3

ATP converted to ADP + Pi(dephosphorylation), providing energy to change shape of carrier protein

Question 4

what is the third step of the Na/K/ATPase pump

Answer 4

3 Na released from pump out of cell, 2 K bind to the carrier pump protein

Question 5

what is the final step of the Na/K/ATPase pump

Answer 5

phosphate(Pi) is released from carrier protein, protein returns to original shape + 2 K released into cell

Question 6

what is the result of the Na/K/ATPase pump in terms of cell membrane potential

Answer 6

outside(+1) of cell becomes more positive than inside(-1)

Question 7

what is the resting potential of the cell

Answer 7

= outside voltage - inside voltage

= -70mV

Question 8

describe the state of Na channel and K channel when cell is at resting potential

Answer 8

voltage-gated Na channels are at resting state

voltage-gated K channels are closed

Question 9

what happens to trigger an action potential

Answer 9

stimulus causes depolarisation to reach threshold

Question 10

describe state of voltage-gated Na channel when threshold is reached(depolarisation phase)

Answer 10

voltage-gated Na channel is activated, gates open, allowing further depolarisation(Na influx)

Question 11

describe the state of the Na and K channels in repolarisation phase

Answer 11

voltage-gated Na channels are closed

voltage-gated K channels are open(K efflux)

Question 12

describe the state of the Na and K channels in the hyper-polarisation phase

Answer 12

voltage-gated Na channels closed

voltage-gated K channels in resting state

Question 13

what is the single most important factor in setting membrane potential

Answer 13

K gradient

Question 14

what is the order of events of an action potential (5)

Answer 14

1- Resting membrane potential
2- Stimulus, threshold is reached
3- Depolarisation phase
4- Repolarisation phase
5- Hyper-polarisation phase