Week1-L2-membrane and action potential

Question 1

flux of ions

Answer 1

n0 of molecules crossing a unit area per unit time

Question 2

diffusion

Answer 2

useful over short distances down conc. gradient till dynamic equilibrium

Question 3

charged molecules proterties

Answer 3

unlike attract and like repel

Question 4

voltage

Answer 4

provide energy to move ions

Question 5

current

Answer 5

movement of charged ions due to potential difference

Question 6

resistance

Answer 6

barrier to movement of ions

Question 7

membrane potential measurements

Answer 7

outside electrode called zero-volt level and inside cell electrode which measure the pd the (negative to outside)

Question 8

ions channels

Answer 8

selective changed of permeability to specific ions and depending on the transmembrane voltage, ligands, and mechanical forces

Question 9

membrane potential if no gradient of charge separation

Answer 9

0

Question 10

membrane potential if ion channels present

Answer 10

increase separation of charge until electrochemical equilibrium is reached

Question 11

electrochemical equilibrium aka the equilibrium potential

Answer 11

electrical forces balance the diffusion forces

Question 12

how to calculate the equilibrium potential

Answer 12

Nernst equation

Question 13

mM of sodium at resting potential

Answer 13

intra-10

extra-150

Question 14

mM of potassium at resting potential

Answer 14

intra-150

extra-5

Question 15

Ek means

Answer 15

equilibrium potential of potassium

Question 16

Ek value

Answer 16

-90mV

Question 17

ENa value

Answer 17

+72mV

Question 18

Em value

Answer 18

-70

Question 19

why membrane potential not at Ek or ENa

Answer 19

membrane has a mix of both K and Na equilibrium across membrane but K»> Na, more towards K potential

Question 20

Goldman-Hodgkin-Katz(GHK) equation

Answer 20

accounts for the relative permeability of ions at one time when calculating the real membrane potential

Question 21

GHK scale for P value-ion channel

Answer 21

0-1 where 0 is closed and 1 is opened

Question 22

depolarisation

Answer 22

Em towards 0mV

Question 23

repolarisation

Answer 23

Em decreases towards resting potential

Question 24

overshoot

Answer 24

Em increase from 0 to more positive

Question 25

hyperpolarisation

Answer 25

Em decrease beyond resting potential

Question 26

graded potential along axon

Answer 26

decay: leakage as impulse propagates

Question 27

graded potential characteristics

Answer 27

change in Em in response to stimulation

occur at synapse and sensory receptors, initiate or prevent ap

Question 28

absolute refractory period mechanism

Answer 28

occurs during the repolarisation period
activation gate open as K+ leaves the cell and inactivation gate close by part of protein plugging the pore.
new action potential cannot be triggered even by strong stimulus

Question 29

relative refractory period mechanism

Answer 29

occurs during the hyper polarisation period where a stronger sitmulsus can trigger an action potential