Capacitative current through cell membrane

[boltdude]

Hello,

I'm having a lot of trouble understanding/visualizing the movement of ions through a capacitor. My book says the total current flowing through a neural membrane (that is in steady state) is equal to the current flowing through ion channels (rm) and the capacitor. However, how can ions flow through a capacitor if the plasma membrane is in the way? Thanks - I'll probably need a dummied down explanation to understand this.

 

[Andy Resnick]

I'm not what you are asking- ion channels/transporters etc. are quite literally little holes in the membrane through which ions flow.

 

[tiny-tim]

Welcome to PF!

I'm having a lot of trouble understanding/visualizing the movement of ions through a capacitor. My book says the total current flowing through a neural membrane (that is in steady state) is equal to the current flowing through ion channels (rm) and the capacitor. However, how can ions flow through a capacitor if the plasma membrane is in the way?

Hi boltdude! Welcome to PF!

I know nothing about the subject , but I remember seeing (but not reading ) a thread in the Biology sub-forum, which may help you: https://www.physicsforums.com/showthread.php?t=258168

 

[natives]

The grammar in which the question was asked is slippery..Because first off current doesn't flow through or across a capacitor,it just builds up,charge is stored...If this is a problem from a physics textbook then revisit the account taking in mind the plasma could just be another dielectric material...If it is from a biology book which i think has something to do with neurons,synapses,the central nervous system,reflex actions and the like then just consider what another had said,plasma membrane has pores through which ions can pass through...The text account I think,was demonstrating the analogy between message transfer in neurons due to ions getting in and out of the membrane as the charging and discharging of the capacitor...You can even consider analogy between this and digital signals because the states are virtually the same,either ON or OFF!Am sure you mistook the book's statement,revisit it again,with consideration of what others have said here at PF!

 

[granpa]

current in = current out

but even with no current in at all the neuron can continue to fire thousands of tumes before it runs out of ions.