PC-505B Manual, Rev. 201013
Warner
Instruments
A Harvard Apparatus Company
50
junction potential
– A difference in conductivity between two dissimilar materials will appear as a small
voltage when the two materials are brought into contact. This voltage is termed the junction potential.
LED
– Light Emitting Diode. The red, green or yellow lighted indicators on the front of many devices. LED’s
are preferred indicator light sources due to their low power consumption.
mean closed time
– The average length of time a gating channel will remain in the closed state.
mean open time
– The average length of time a gating channel will remain in the open state.
mini-jack
– A small plug on the headstage to which the electrodes are attached.
model cell
– An electric circuit designed to model the electrical characteristics of a biological membrane.
open probability
– The calculated probability of finding a channel open at time t, given that the channel is
in a closed state at time t=0.
oscilloscope
– A device used to monitor voltages within an electrical circuit.
output current
–
See
Im
OUTPUT SYNC
– A pulsed signal appearing at the
OUTPUT SYNC
BNC on the instrument rear panel. Used to
synchronize the
PULSE GENERATOR
or
CAP TEST
signal to an external device such as an oscilloscope.
periodic
– That which repeats itself at regular intervals.
perfusate
– The solution being perfused.
perfusion
– The exchange of one solution with another.
plasma membrane
– The surface membrane of a cell. Contrast with an intracellular membrane which is a
membrane contained entirely within the cell.
potentiometer
– A single- or multi-turn dial used to make a continuously varying selection with a range. In
its heart this is a variable resistor.
pulse code modulator
– A device which converts an analog signal into a form acceptable for storage on
VCR tape. Also converts data previously stored on VCR tape back into an analog signal.
signal polarity
– Defined as the sign applied to a current generated through a membrane in the presence
of an applied holding potential. The electrophysiological definition is determined by the membrane
such that an outward directed current and a depolarizing potential are both positive.
single channel
– Refers to a solitary channel protein functioning within a measurement milieu.
step potential
– A functionally instantaneous change in potential from one value to another.
time constant
– In a system governed by exponential kinetics this is the time required for a value to change
to 1/
e
of its initial value, where
e
=2.71828 is the base of the natural logarithm.
transient
– Momentary.
transmembrane
– That which spans a membrane or is referred from one side of a membrane to the other.
trim pot
– An adjustable variable resistor used for making fine adjustments to a circuit.
