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Right answer is (a) negative

Explanation: DC AMPLIFIERS are generally of the negative feedback type. They are used for medium gain applications down to about 1 MV signal levels for full scale. They are not practical for very low level applications because of dc DRIFT and POOR common-mode rejection capabilities.

Correct CHOICE is (a) True

Explanation: Modern EMG machines are PC based available both in a console as well as laptop models as they provide full colour waveform display, automatic cursors for marking and MAKING measurements and a keyboard for access to convenient and IMPORTANT test controls. Ambulatory monitoring of ECG is CALLED ‘Holter Cardiography’, after Dr. Norman Holter who introduced this concept in 1962. A Holter monitor is a type of ambulatory electrocardiography device, a portable device for cardiac monitoring (the monitoring of the electrical activity of the cardiovascular system) for at least 24 hours (often for two weeks at a time).

The correct answer is (d) OPTICAL system

Explanation: A detecting system for the measurement of unabsorbed RADIANT energy, which could be the human eye, a barrier-layer cell, phototube or photo-multiplier tube. An optical system for producing a parallel BEAM of filtered light for passage through an absorption cell (cuvette). The system may include lenses, mirrors, slits, DIAPHRAGM, etc.

Right choice is (b) pressure electricity

Easiest explanation: PIEZO-electricity is pressure electricity. The piezo electric EFFECT is a property of natural crystalline substance to develop electric POTENTIAL along a CRYSTALLOGRAPHIC axis in response to the movement of charge as a result of mechanical deformation.

The correct choice is (C) 50 uV/cm

Best explanation: A typical value of the calibration signal is 50 uV/cm. A CALIBRATING signal is USED for controlling and documenting the SENSITIVITY of the AMPLIFIER channels. This supplies a voltage step of adequate amplitude to the input of the channels.

Right answer is (b) EMG

The explanation: EMG measurements are also important for the myoelectric control of prosthetic devices (artificial limbs). This is the most DEMANDING requirement from an EMG since on it depends on the working of the prosthetic device. This USE involves picking up EMG signals from the MUSCLES at the terminated nerve endings of the remaining limb and using the signals to activate a mechanical ARM.

Correct choice is (B) False

For explanation: It is False. Three METHODS are used in the design of isolation amplifiers: (i) transformer isolation (ii) optical isolation (iii) CAPACITIVE isolation. Isolation amplifiers are commonly used for providing protection against leakage currents. The isolation INCLUDES different supply voltage sources and different GROUNDS on each side of the isolation barrier.

Correct choice is (d) transducer

Easy explanation: TRANSDUCERS CONVERT biochemical events into measurable signals. They PROVIDE the means for detecting the biochemical changes inside the body. PARTICULARLY biosensors are employed for this purpose.

Right choice is (a) forehead

Explanation: The reference electrode is GENERALLY placed on a nonactive site such as the forehead or EARLOBE. A pattern of electrodes on the head and the channels they are connected to is called a MONTAGE. Montages are always SYMMETRICAL.

Correct option is (C) EEG

Explanation: EEG, describing the general FUNCTION of the brain activity, is the superimposed wave of neuron potentials operating in a non-synchronized MANNER in the physical sense. Electroencephalograph is an INSTRUMENT for recording the electrical activity of the brain, by suitably placing surface electrodes on the scalp.

Correct ANSWER is (a) True

The best explanation: It is True. OPTICAL FIBER sensors are electrically passive and CONSEQUENTLY immune to electromagnetic disturbances. They can be miniaturized and are most SUITABLE for telemetry applications. They are geometrically flexible and corrosion resistant.

Right OPTION is (b) OPTIC fiber SENSORS

Easy explanation: Optical fibre sensors are non-electrical and hence are free from electrical interference usually associated with ELECTRONICALLY BASED sensors. Optic sensors are used for endoscopic imaging. They are suitable for telemetry applications as the bulk of the instrumentation can be at a reasonable distance from the patient.

The correct option is (c) TEFLON

Easy EXPLANATION: The wire is BARE only at the tip. The MONOPOLAR needle electrode consists of a teflon coated stainless steel wire.It is found that after the needle has been used a number of times, the teflon coating will RECEDE, increasing the tip area. The needle should be discarded when this happens.

The correct choice is (b) frequency measurement of fiber optic sensor

The best I can EXPLAIN: Doppler velocimetry works on the principle of frequency measurement of fiber optic sensor. The moving red blood cells scatter the light and produce a Doppler frequency SHIFT because of their movement. In this method, light from a laser, NORMALLY helium/neon, is sent via a FIBRE onto the skin surface.

The correct CHOICE is (b) 20 MM/s

The explanation is: Time measurements and heart rate measurements are made horizontally on the electrocardiogram. Electrocardiograms are ALMOST invariably recorded on GRAPH paper with HORIZONTAL and vertical lines at 1 mm intervals with a thicker line at 5 mm intervals.

Correct OPTION is (d) variable resistance

To elaborate: The principle behind strain gaude is the variable resistance. A linear relation exists between the deformation and electrical resistance of a suitable selected gauge over a SPECIFIED range. The transducer is based upon the CHANGED in resistance of a WIRE produced due to SMALL mechanical displacement.

Correct choice is (b) ground ELECTRODE

To explain: A ground electrode is necessary for providing a common reference for measurement. The signal can then be amplified and displayed on the screen of a cathode ray tube. It is also applied to an audio AMPLIFIER connected to a loudspeaker.These ELECTRODES pick up the POTENTIALS produced by the contracting muscle FIBRES.

Correct choice is (d) Position of electrode

Best explanation: The amplitude of the EMG signals DEPENDS upon VARIOUS factors, e.g. the type and placement of electrodes USED and the degree of muscular exertions. The needle electrode in contact with a single muscle fibre will pick up spike type voltages whereas a surface electrode picks up many overlapping spikes and THEREFORE produces an average VOLTAGE effect.

Correct option is (b) False

To explain I would say: The electrode consists of a LIGHT weighted METALLED screen or plate held away from the SUBJECT by a flat washer which is connected to the skin. In floating electrode the METAL electrode does not make direct contact with the skin. Floating electrodes can be recharged, i.e. the jelly in the electrodes can be REPLENISHED if desired.

Correct choice is (a) EEG

Easy explanation: ELECTROENCEPHALOGRAPH is an instrument for recording the electrical activity of the brain, by SUITABLY placing SURFACE electrodes on the scalp. EEG, describing the general function of the brain activity, is the SUPERIMPOSED wave of neuron potentials operating in a non-synchronized manner in the PHYSICAL sense.

Correct choice is (B) smart pad

The explanation is: Smart pad is a system that displays patients electrocardiogram signals without adhesive pads, wires or active intervention from a clinician.The selected electrodes are used to provide a DIFFERENTIAL 3 lead measurement of the patient’s ECG, which is then transmitted wirelessly and DISPLAYED on a laptop computer. The system automatically selects three electrodes from an array of Cu/Ni FABRIC based electrodes patterned on a thin pad on which the patient lies.

Correct OPTION is (b) False

The EXPLANATION is: It is False. EMG is usually RECORDED by using surface electrodes because the surface electrodes may be disposable, adhesive types or the ONES which can be used repeatedly.

Correct CHOICE is (b) Intravascular Oximeter

Explanation: Mixed venous saturation varies in REFLECTING the changes of oxygen saturation, cardiac output, HAEMATOCRIT or haemoglobin content and oxygen consumption. Intravasacular oximeters are NORMALLY used to MEASURE mixed venous saturation, from which the status of the circulatory system can be deduced.

The CORRECT option is (b) greater than 90 dB

The explanation: The common-mode rejection should be greater than 90 dB up to 5 kHz.The main amplifier has controls for gain adjustment from 5 mV/div to 10 mV/div for SELECTING the SENSITIVITY most appropriate to the incoming signal from the PATIENT. A calibrating square wave signal of 100 mV (peak-to-peak) at a frequency of 100 Hz is usually available.

Correct ANSWER is (d) More than 2

Easiest explanation: Currently available fiber-optic oximeters UTILIZE more than two wavelengths to adjust for haematocrit variation. For estimating SO2, usually the reflectance at two wavelengths, one in the red and the other in the near infrared regions, are USED.

Correct option is (b) LOW FREQUENCY response

To EXPLAIN: The response should be down to less than ONE hertz which is a very frequent REQUIREMENT. The bioelectric signals in medical science contain components of extremely low frequency. Thus the amplifiers must also have a low frequency response.

Correct OPTION is (d) low frequency response

For explanation: In all RC-coupled amplifiers, low frequency response is limited by the reluctance of the COUPLING capacitors. The response should be down to less than ONE HERTZ which is a very frequent REQUIREMENT. To achieve the low frequency response required for medical applications, the amplifier must have large values of coupling capacitance.

Correct answer is (a) SPHERE

The explanation is: Leucocytes are in the shape of a sphere. Leucocytes have a nucleus. They live for seven to FOURTEEN days and there is a rapid TURN over, with constant DESTRUCTION and replacement. There are normally 5000–10,000 white cells per CUBIC mm of blood but their number varies during the day.

Correct choice is (b) False

The explanation: It is False. Leucocytes form the defence MECHANISM of the body against infection. The NUMBER and proportion of these types of leucocytes may vary WIDELY in response to various disease conditions. They are of two main types: the neutrophils and the lymphocytes. Neutrophils INGEST BACTERIA and lymphocytes are concerned with immunological response.

Right answer is (a) True

The best explanation: It is True. NEUTROPHILS are nearly twice as big as the red cells.Lymphocytes are of the same size as the red cells but contain a large density STAINING NUCLEUS and no GRANULES. Neutrophils contain both a nucleus DIVIDED into several lobes and granules in their protoplasm.