action potential basics

Question 1

what is meant by the terms hyperpolarisation and depolarisation

Answer 1

hyperpolarisation = the membrane potential becomes more negative
depolarisation = the membrane potential becomes less -negative, or even positive

Question 2

ionic movements across the cell membrane cause changes in membrane potential, what does the direction of this change depend on

Answer 2

the direction of the movement of the ion, into(influx) or out of(efflux) of the cell
the charge carried by the ion(+ve or -ve)

Question 3

what do ions require in order to move across the membrane

Answer 3

requires ion channels or transporters

Question 4

describe the movement of Na+ in response to the open of cell membrane sodium selective channels

Answer 4

Na+ flows in to the cell because both the electrical and conc. gradient are inward

Question 5

describe the relationship between Ena and the resting membrane potential of many neurons

Answer 5

Ena = ~+60mV whereas resting membrane potential is ~-70mV

Question 6

describe the movement of K+ ions in response to the opening of cell membrane potassium selective channels

Answer 6

K+ ions flow outwards because conc. gradient flows outwards which exceeds the inward flowing electrical gradient

Question 7

describe the relationship between Ek and the resting membrane potential of most neurons

Answer 7

Ek = ~-100mV whereas resting membrane potential =~70mV

Question 8

dscribe the effect on the cell membrane from the opening of the Na+ and K+ channels opening

Answer 8

Na+ = membrane potential driven towards Kna(~+60mV)
K+ = membrane potential driven towards Kk(~-100mV)