physio Q - crackingtheboards

[ArchivalUser]

if the equilibrium potential for Na+ and K+ is +60 and -100 respectively wat will be the membrane potential at which 3/4th of conduction is due to k+ and the rest is due to Na+

A -20mV
B -40mv
C -60mv
D -80mv
E -100mv

[ArchivalUser]

anyone??????

[ArchivalUser]

either C or D....I will go for C

[ArchivalUser]

can u explain why?
it is the right answer

[ArchivalUser]

-75+20=-55.....

[ArchivalUser]

duh???? where do u get those numbers from

[ArchivalUser]

ok so....3/4 of the pull of K+ is 3/4x100 which is 75 pulling negative towards the eq pot of K
and ......1/4 of the pull of Na+ is 1/4x60 which is 20 pulling positive towards the eq pot of Na

so the difference of the pulls and the direction of the pulls is as follows...-75+20=-55.......

pulls means the conductance.

[ArchivalUser]

good explanation man....infact u got it spot on...1/4th of 60 is 15 and -75+15= -60...thnx

[ArchivalUser]

D.

[ArchivalUser]

jeez my math aint up to much...but good to see it didnt screw up the ans.