the resting potential membrane Flashcards
what does the membrane potential refer too
refers to the separation of opposite charge that exists across the cell membrane
what causes the Resting potential (3)
- selectively permeable membrane - (K+) through leaky ion channels it also does allow some sodium through (NA+)
- NA+, K+ ATPase pump
- unequal distribution of ions
what does A- represent
represents intracellular proteins
describe the distributions of K+ ions
the positively charge K+ leak out down the concentration gradient whereas the A- stay inside the cell as they are intracellular proteins.
the positively charged K+ then move back in through an electrical gradient
describe the distribution of NA+ ions
the positively charged sodium move in down the concentration gradient whereas the cl- stay out of the cell
then the NA+ cell go back out through an electrical gradient.
what is the equation for equilibrium potential for an ion
Ek= 61/number of ion multiply by log (conc outside cell/conc inside cell)
explain 3 reasons why a separation charge exists across the cell membrane
a separation of charge exists across the membrane of all cells due to
•an unequal distribution of key ions
•the selective permeability of the membrane
•the Na+ K+ ATPase pump (pumps 2K+ into the cell for every 3Na+ out of the cell)
what is the typical value of RMP inside the cell
-70mV
what are the Terms used to describe changes in membrane potential
- polarised- means charged e.g.-70mV
- depolarisation- means reduction in charge e.g. -70mV goes to -30mV
- hyperpolarised- means an increase in charge e.g.-70mV goes to -90mV
what is the RMP closer to K+ or NA+
It is closer to Ek than ENa because the resting potential is more permeable to K+
At RMP neither K+ OR Na+ is equilibrium so what happens to prevent these ions
At RMP neither K+ or Na+ ions are at equilibrium, hence passive diffusion of these ions is prevented by the action of NaK ATPase
