Term
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Definition
E=I*R
or
V=I*R
E= electromotive force or voltage (V) (volts)
I=electric current or flow of electrons (Amperes)
R=resistance (Ohms)
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Term
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Definition
provide the energy to operate the circuit
may take the form of a battery or a time varying constant voltage or a constant current source |
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Term
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Definition
| travels down the voltage gradient from + to - |
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Term
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Definition
| from the source of electrons to the deficit from - to + |
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Term
direct current (DC) source
(time invariant) |
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Definition
no changes in voltage with time
ex: output of a battery |
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Term
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Definition
| delivers the specified current irrespective of whatever voltage it takes to produce the current |
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Term
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Definition
| produces the specified voltage regardless of the current that must flow |
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Term
| Alternating current (AC) sources |
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Definition
produce voltages or currents that are time varying
V(t)=A*sin(ωt+Φ)
V=voltage
A=peak amplitude (Vp)
ω=radian frequency (frequency in Hz f=ω/(2*π) or
ω=2*π*f)
t=time (seconds)
Φ= phase delay (radians) usually 0 |
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Term
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Definition
I(t)=A*sin(ωt+Φ)
the source driving the circuit is a current rather than a voltage
useful when modeling the cardiovascular system if you need the CO to remain constant |
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Term
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Definition
combinations of alternating current (time varying) and direct current (time invariant)
the mean goes from 0 to the value of the time invariant signal
ex: V(t)=10*sin(12.566*t)+8 the mean is 8 volts |
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Term
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Definition
measurement is one of voltage (electrical potential) vs. time
mean contains no clinical info. |
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Term
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Definition
signal generated by the mechanical action of the myocardium squeezing blood into the hydraulic impedance of the vasculature
example of a mixed (AC+DC) signal source |
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Term
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Definition
| useful when the maximum stress on the blood vessel wasll is an important consideration, as in patients with aneurysms, intracranial hypertension |
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Term
mean blood pressure
(systolic/diastolic) |
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Definition
| useful determinant of organ perfusion especially when considered as perfusion pressure (mean arterial pressure minus venous pressure) |
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Term
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Definition
| important when considering perfusion of the left ventricle (majority of the left ventricular blood flow occurs during diastole) |
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Term
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Definition
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Term
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Definition
measurement of the change in volume of the pulsatile blood vessels as detected by light passing through the tissue of interest
most useful info derived is the amplitude of the volume signal |
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Term
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Definition
mean values of blood pressure and mean values of CO
used to calc. systemic vascular resistance
SVR=(MAP-MCVP)/(mean CO) |
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Term
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Definition
| diastolic and systolic pressure |
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Term
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Definition
| has signal amplitude on the Y axis which is the ratio of output signal amplitude to the amplitude of the input signal and frequency on the X axis |
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Term
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Definition
| has an amplitude ratio of 1: output and input amplitudes are the same=perfect reproduction |
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Term
| curve above ideal response |
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Definition
| output signal is greater than input signal and at that frequency the input signal is artifically amplified and the output signal is distorted from the input signal |
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Term
| curve lower than ideal response |
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Definition
| the amplitude of the output signal at that frequency is artifically attenuated or less than the amplitude of the input signal. indicates that the output signal is a distorted form of the input signal |
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Term
| a frequency of 0 corresponds to... |
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Definition
| the mean or DC component, which is reproduced exactly because the amplitude of the system response at zero frequency is 1 |
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Term
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Definition
a method for describing complex waveforms in terms of more manageable sine an cosine waves
sine waves can be added together in order to produce a more complex waveform
as higher and higher order odd harmonics are added to the fundamental, the waveform becomes a better approximation to the goal of producing a perfect square wave |
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Term
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Definition
| the basic period of the waveform |
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Term
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Definition
| an integer number times the fundamental frequency |
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Term
| 1st term of the Fourier series |
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Definition
represents the mean of the waveform and it is a term that has no frequency associated with it
by definition the mean is a constant, independent of frequency
even a system with inadequate frequency response is still capable of accurately measuring the mean of the waveform |
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Term
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Definition
| electronic methods for removing unwanted frequencies from signals |
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Term
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Definition
frequencies below the cutoff are allowed to pass through but frequencies above the cutoff are removed |
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Term
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Definition
| high frequencies are permitted to move through the filter and low frequencies are removed |
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Term
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Definition
small region where only certain frequencies can pass through
there is a low pass cutoff frequency at f1 and a high pass cutoff frequency at f2 with a center frequency for the pass band |
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Term
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Definition
passes all low and high frequency signals but rejects the frequencies that are above the lower cutoff f1 and below the upper cutoff f2
used in ECG monitoring to eliminate the 60 Hz interference |
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Term
| standard ECG frequency response |
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Definition
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