true and false - 8
Most instruments for physiological measurements consist of a sensing element, an amplifie
and a display device.
T
The electrical image of physiological data can be easily transmitted to a remote monitoring point, amplified and displayed in an appropriate manner.
T
When two dissimilar metals are brought together, a contact voltage is generated which is proportional to the volume of the junction.
F
If one junction of a thermocouple is at 10 °C, there will be a net voltage which is proportional to the temperature difference between the two junctions.
T
Thermocouples can be made small enough to be incorporated in the tip of a hypodermic needle.
T
Electrical-resistance thermometers operate on the principle that electrical resistance varies with changes in temperature.
T
Electrical-resistance thermometers are the most accurate of the electrical temperature sensors used for physiological measurements, but they cannot be miniaturized like the thermocouples and thermistors.
T
The thermistor is less sensitive than the thermocouple and less easily calibrated.
F
Thermistors are used in dialysis machines as safety devices to shut off the dialysis if the temperature of the dialysate liquid is outside temperature limits.
T
Solid-state integrated circuits are miniaturized elements containing many transistors.
T
When a pressure is exerted on a piezoelectric crystal, a small potential difference is generated between the surfaces of that crystal.
T
The grid controls the flow of charge through the triode vacuum tube. It is given a negative potential to form a repulsive barrier which the electrons must surmount before they can move to the anode.
T
The transistor is the solid-state analog to the triode vacuum tube.
T
The main advantage of an oscilloscope over a voltmeter is that it can be used to follow the change of voltage over time in an AC circuit, rather than just measure the average voltage.
T
The monitor in an operating room may simultaneously display systolic and diastolic pressure, pulse rate, respiration rate, the ECG signal, etc.
T
The moving coil meter is mainly a current measuring device, but it can be adjusted to measure voltages or resistances as well.
T
The valve action of the grid in triodes accomplishes the desired amplification of the input signal.
T
One of the standard items of emergency equipment in a hospital is the high voltage device known as the multimeter.
F
When life-threatening ventricular fibrillation occurs for any reason, a momentary large current flow through the heart may stop the fibrillation and resume the normal heart rhythm.
T
Electrosurgical instruments are used for either cutting tissue or welding tissue together.
These instruments generate low frequency currents at voltages up to 15 000 V.
F
The high voltage caused by several amperes of current entering the body through the small area of the probe accounts for the cutting and cauterizing action.
T
In the case of measurements such as the ECG and EEG, a voltage generated by the body is measured.
T
A nonelectrical physiological variable can be converted to an electrical signal by a sensor which is called defibrillator.
F
As the electrons are released by the cathode of the triode, they are attracted by the anode and move uphill, causing a current to flow through the tube.
F
A multimeter can measure voltages, currents and resistances. To achieve this objective, proper circuits are incorporated with the galvanometer.
T
If a battery of known voltage is connected in series with the galvanometer, then it can be used as an ammeter.
F
A current-carrying wire experiences a force when placed in an external magnetic field.
T
The defibrillator is similar in principle to the parallel plate capacitor.
T
In metals the resistance to current flow decreases with the increase in temperature.
F
The electrical resistance thermometer is the most accurate temperature sensor used for physiological measurements, but it cannot be miniaturized like thermistors and thermocouples.
T