## How to calculate Cell's Total Capacitance (not cm)?

Moderator: wwlytton

Krishna Chaitanya
Posts: 70
Joined: Wed Jan 18, 2012 12:25 am
Location: University of Pavia

### How to calculate Cell's Total Capacitance (not cm)?

Hi,

I am interested in knowing about the calculation of cell's total capacitance (not specific membrane capacitance (cm)). Under the biophysical properties of a section, cm is specified but I wanted to know the calculation of total membrane capacitance.

Could you kindly let me know how to do this? As I am a learner, detailed explanation could be very helpful.

ted
Posts: 5772
Joined: Wed May 18, 2005 4:50 pm
Location: Yale University School of Medicine
Contact:

### Re: How to calculate Cell's Total Capacitance (not cm)?

Good question. In pseudocode the algorithm would be

Code: Select all

``````cmtotal = 0
for each section
for each segment
cmtotal += segment_area * segment_cm``````
In hoc I'd implement this as a function

Code: Select all

``````func totalcm() { local tmp
tmp = 0
forall for (x,0) tmp += area(x)*cm(x)
return tmp
}``````
The NEURON Programmer's Reference contains informative entries about the following:
func
local variables in functions
forall
for (x,0) and for (x)
area()
cm
syntax
expression

"Why did your pseudocode use a variable called cmtotal, but your function used a different name?"
No reason, actually.

Krishna Chaitanya
Posts: 70
Joined: Wed Jan 18, 2012 12:25 am
Location: University of Pavia

### Re: How to calculate Cell's Total Capacitance (not cm)?

Thank you Ted for the quick reply.

ted