# biophysics

## 33 terms

### Phase

is the current flow in one direction for a finite period of time

### Reistance

is paramter which opposes the movement of electric charges. the relationship between current and resistance is provided by ohms law. R= V/I

### Voltage

is the driving force required to move electric charges. it is measured in volts (v)

### Amplitude

is the measure of maximum value with reference to the baseline. termed intensity

### Intensity

is the magnitue of current or voltage applied by the unit and can be measured in miliamps (MA)

### Anode

in electrode circuit it is the positively charged

### Cathode

in electrode circuit it is the negatevely charged

### electric current

is the flow of electric charges (electron beam in metal or ions in electrolyte)

### Types of current

direct current
alternating current
pulsed current

### derect current

is one in which undirectional current flows continousuly over time

### alternating current

is one which bidirectional current clows continuously over time

### pulsed current

is one in which undirectional or bidirectional flow of current periodically ceases over time

### cathode

is negatvely charged.
as deporazation of the nerve membrane occurs under the cathode, it is therefore commonly termed the active electrode.
as electrical current flows from cathode to anode, negative charges tend to accumulate on the outer surfeace of the nerve fiber membrance as they will be repelled by negatviely charged cathode

### electrolysis

is a distribution of the electrolyte and production the metal and gas on electrodes

### Anode and Cathode

in electrode circuit, one electrode is postively charged (anode) and the other negatively charged (cathode)

### electrolytic dissociation

NaOh --> Na + OH (Cathode)
HCL --> H + Cl (Anode)

on the Cathode it prodes alkaline reaction (OH) and on the anode the acid reaction (H)

### Cathode reaction

2Na + 2H20 --> 2 NaOH + 2H2 (Cathode)
produces a free hydrogen and sodium hydroxyide

### Anode reaction

2Cl + H20 --> HCl + O (Anode)
produces free oxygen and hydrocholeric acid

### Electrolysis

is a distribution of the electrolyte and production of metal and gas on electrodes

### a monophasic waveform

means that the current flows in only one direction, therefore, one electrode acts as the cathode (negagtive) and the other as the anode (positive)

### Decay time

is the time for the terminal edge of the phase to return to zero baseline from the peak amplitude of the phase

### rise time

is the time for the leading edge of the phase to increase from the baseline to the pack amplitude of the phase

### interpulse interval

is the time between two successive pulses

### pulse duration

is the time elapsed from the begining to the end of al lphases in one pulse

### interphase interphase

is the time between two succesive components of a pulse when no electrical activity occurs

### a bisphasic wavelength

means that current flows in both direction, thus each electrode acts a cathode for some part of the waveform

### frequency

is the repetition rate of a waveform (# of pulses delivered per second)
frequency = 1 second/period
is a time-dependent characteristic which is measured in Hertz (h2) or in pulses per second (pps)
a frequency of 150Hz means that 150 pulses are delivered per second. the frequency of an alternating + pulsed current can be calculated using
Frequency = 1 second / period

### period

is the time elapsed between a specific point on the waveform of the pulse to the pulse to the identical point on the next pulse

### in alternating current

the waveform duration is equal to one period (one complete cycle)
in pulsed current the period equals the pulse duration pulus the interpulse interval

### current modulation

Pulsed and alternating currents can be modulated, that is varied within a special time frame.
these modulation may be used alone or in combiation and they may be sequential or varied with respect to pulse per cycle or a series of pulses per cycle

### amplitude modulation

is a varaition in the peak intensity inseries of pulses or cycles

### Ramp

is increases and decrease in the phase charge over time

### train of pulses

is a continous repetive sequence of pulses or cycles of pulsed current