Biomedical Instrumentation Questions and Answers
Question 1. Define Absolute Refractory Period (ARP)?
Answer :
During the initial portion of the action potential, the membrane cannot respond to any stimulus, no matter how intense the stimulus is. This interval is called ARP.
Question 2. Define Relative Refractory Period (RRP)?
Answer :
ARP is followed by relative refractory period. During this period, action potential can be elicited by a super threshold stimulus.
Question 3. What Are Sensory Nerves, Motor Nerves And Mixed Nerves?
Answer :
The nerves that carry the information gathered by the sensory organs to the brain are called sensory nerves. They serve as message carriers for the brain. Motor nerves carry back the orders from the brain to the muscles and glands. Mixed nerves perform the function of the both sensory and motor nerves.
Question 4. What Are Resting Potential?
Answer :
The membrane potential measured when a equilibrium is reached with a potential difference across the cell membrane negative on the inside and positive on the outside is called resting potential.
Question 5. What Is Action Potential?
Answer :
When a stimulus is applied to a cell at the resting stage, there will be a high concentration of the positive ions inside the cell. So there will be slightly high potential on the inside of the cell due to imbalance of potassium ions. This is called action potential.Range:20Mv.
Question 6. What Are Cerebellar Stimulators?
Answer :
In case of epilepsy, chronic stimulation to the cerebellum is provoked by transcutaneous inductive coupling, through an antenna fixed subcutaneously on the chest. The electrodes are placed on anterior or posterior lobe of cerebellum. Such stimulators are called cerebellar stimulators.
Question 7. What Is The Principle Of Ultrasonic Diathermy?
Answer :
In this method, the heating effect is produced because of the ultrasonic energy absorption property of the tissues. The amount of energy absorbed by the tissues is dependent upon the frequency of ultrasonic waves from a conventional crystal oscillator.
Question 8. What Is Microwave Diathermy?
Answer :
Microwave diathermy involves the process of irradiating tissues of the patient‟s body with very short wireless waves having frequency in the microwave region. Typically, the frequency used is 2450 MHz corresponding to a wavelength of 12.25 cm. Heating effect is produced by the absorption of the microwaves in the region of the body under treatment.
Question 9. What Are Bladder Stimulators?
Answer :
Bladder stimulators are those which activate the micturition reflex by remote electronic stimulation of a permanently implanted spinal electrode.
Question 10. Define Blending?
Answer :
When the electrode is kept above the skin, the separated tissue or nerves can be welded or combined together by an electric arc. This is called blending.
Question 11. What Is Diathermy?
Answer :
The term Diathermy means „through heating‟ or producing deep heating directly in the tissues of the body. In the practice of physiotherapy, diathermy is used for producing heat stimulus by application of high frequency energy.
Question 12. Define Hemodialysis?
Answer :
It is the removal of chemical substances form the blood by passing it through tubes made of semipermeable membrane.
Question 13. Define Dialysis?
Answer :
It is used in the treatment of acute or chronic renal (kidney) failure. It is a process which involves removal of waste products from blood and obtaining normal pH.
Question 14. What Is Bio Electric Potential?
Answer :
Certain systems of the body generate their own monitoring signals conveying useful information about the functions they represent. Such signals are bio electric potentials and are related to nerve conduction, brain activity, heart beat etc.
Question 15. What Are The Different Types Of Muscles?
Answer :
Voluntary muscles: work at our will (arm muscle).
Involuntary muscles: work without our knowledge (muscle in the food canal).
Cardiac muscles: help in functioning of the heart and are working day and night without tired.
Question 16. Define Linearity?
Answer :
Linearity of an instrument is defined as the degree to which variations in the output of an instrument follow input variation. Whenever the sensitivity of the instrument is constant overall levels of the input, then that instrument has better linearity. Linearity is essential to get accurate values.
Question 17. State All Or Nothing Law?
Answer :
Regardless the method of excitation of cells or the intensity of the stimulus, which is assumed to be greater than the threshold of stimulus, the action potential is always the same for any given cell. This is known as the all or nothing law.
Question 18. What Is Meant By Sodium Pump?
Answer :
It is an active process, by which the sodium ions are quickly transported to the outside of the cell and the cell again becomes polarized& assumes its resting potential. The operation of this pump is linked with the influx of potassium into the cell, as if a cyclic process involving an exchange of sodium for potassium existed.
Question 19. Define Evoked Potential?
Answer :
Evoked potentials are the potentials developed in the brain as the responses to external stimuli like light, sound etc. The external stimuli are detected by the sense organs which causes changes in the electrical activity of the brain. It is also called Event related potential.
Question 20. Define Ectopic Focus?
Answer :
A portion of myocardium (or the AV node or the specialized conduction system) sometimes becomes “irritable” and discharges independently. This site is called ectopic focus.
Question 21. What Is Demand Pacemaker?
Answer :
It is a pacemaker with the feed back loop which detects the QRS complex of ECG signal from electrodes and amplifies it. This resets the timer present inside and the heart rate is maintained at 60-80 BPM.
Question 22. What Is NSR ?
Answer :
NSR- Normal Sinus Rhythm, Any change in the NSR results in a condition called Arrhythmia. It can also cause Bradycardia. A condition of slow heart where the heart rate reduces to 30-50 beats per minute (BPM) resulting in insufficient blood supply to the human body. It causes dizziness and loss of consciousness.
Question 23. What Is The Cardiac Pacemaker And Why Is It Used?
Answer :
It is an electrical stimulator that produces periodic electric pulses that are conducted to electrodes located on the surface of the heart (Epicardium), within the muscle (myocardium) or within the cavity or the lining of the heart (Endocardium).
Question 24. What Is Desiccation?
Answer :
The needlepoint electrode are struck into the tissue and kept steady while passing electric current. This creates a high local increase in heat and drying of tissues. This is called desiccation which produces dehydration in the tissues.
Question 25. Define Electrotomy?
Answer :
When the electrode is kept above the skin an electric arc is sent. The develop heat produces a wedge shaped narrow cutting of the tissue on the surface. By increasing the current level, deeper level cutting of the tissues takes place. Normally continuous RF current is used for cutting.
Question 26. What Is Endoscopy?
Answer :
It is a tubular optical instrument to inspect or view the body cavities, which are not visible to the naked eye normally. Gasto-intestinal, fiberoscope (intestinal), Broncho fiberoscope (trachea), Laparoscopy (abdomen), Sigmoidoscope (rectum), Cystoscopy (urinary bladder) etc.
Question 27. What Is Thermograph?
Answer :
The human skin is almost a perfect emitter of infrared radiation proportional to the surface temperature at any location of the body. Thermograph is an infrared thermometer incorporated into a scanner so that the entire surface of a body or some portion of the body is scanned and the infrared energy is measured and used to modulate the intensity of a light beam that produces a map of the infrared energy on photographic paper.
Question 28. What Is A Defibrillator?
Answer :
A defibrillator is an electronic device that creates a sustained myocardial depolarization of a patient’s heart in order to stop ventricular fibrillation or atrial fibrillation.
Question 29. What Is GFI ?
Answer :
Ground fault interrupter protects patients against a macro shock that occurs if a person touches the hot lead with one hand and the ground with the other.
Question 30. What Is Macro Shock?
Answer :
A physiological response to a current applied to the surface of the body that produces unwanted stimulation like muscle contraction or tissue injury is called macro shock. Taking the least body resistance to be 1K ohms the inter electrode voltage on the order of 75-120V could be dangerous.
Question 31. What Is Micro Shock?
Answer :
A physiological response to a current applied to the surface of the heart that results in unwanted stimulations like muscle contractions or tissue injury is called micro shock. It is caused when currents greater than 10ÎĽA flow through an insulated catheter to the heart. Proper protection circuits should be used to overcome the micro shocks.
Question 32. Define – Radio Pill?
Answer :
It is a pill that contains a sensor plus a miniature transmitter is swallowed and the data are picked up by a receiver and recorded. Such radio pills are used to monitor stomach pressure or pH.
Question 33. What Is Biotelemetry?
Answer :
Bio-telemetry is the electrical technique which permits examination of the physiological data of man or animal under normal conditions and in natural surroundings without discomfort to the patient under investigation.
Question 34. Define Nuclear Magnetic Resonance Signal?
Answer :
A patient in an external magnetic field causes the magnetization of protons of hydrogen atoms in his body. Due to magnetization, these protons align and process about the external magnetic field, now a radiofrequency pulse at resonance frequency is transmitted into the patient under controlled condition. The resonance condition proton responds by emitting radiofrequency signal. This is called nuclear magnetic resonance signal.
Question 35. What Are The Methods Involved In Direct Blood Pressure Measurement?
Answer :
- Auscultator method
- Palpatory method
Question 36. What Are The Causes Of Cerebrovascular Accident (CVA)?
Answer :
When the blood flow in a certain vessel is completely obstructed, the tissue in the area supplied by this vessel may die. Such an obstruction in a blood flow of the brain is one of the causes of CVA or stroke.
Question 37. What Is Cardiac Output And Its Normal Rate?
Answer :
Blood flow is highest in the pulmonary artery and the aorta, where the blood vessels leave the heart. The flow at these points is called cardiac output, is between 3.5 and 5liters/min in a normal adult at rest.
Question 38. Give The Methods For Measuring Blood Flow?
Answer :
Indirect method – sphygmomanometer.
Direct method
Percutaneous insertion
Catheterization (vessel cut down)
Implantation of a transducer in a vessel or in the heart.
Question 39. What Is Myocardial Infarct And Angina Pectoris?
Answer :
An obstruction of part of the coronary arteries that supply blood for the heart muscle is called myocardial infarct or heart attack, whereas merely a reduced flow in the coronary vessels can cause a severe chest pain called angina pectoris.
Question 40. What Is Auscultation?
Answer :
The technique of listening to sounds produced by organs and vessels of the body is called auscultation.
Question 41. Discuss About The Origin Of Heart Sounds?
Answer :
With each heart beat the normal heart produces two distinct sounds described as “Lub-Dub”. The lub is caused by the closure of the atrioventricular valves, which permits flow of blood from the atria into the ventricles .this is called the first heart sound, it occurs approximately at the time of the QRS complex of the electrocardiogram. The dub part of the heart sounds is called the second heart sound and is caused by the closing of the semilunar valves, occurs about the time of the end of the T wave of the cardiogram. A third heart sound is heard especially in young adults. Atrial heart sound is not audible and it occurs when the atria do not contract.
Question 42. Define Motion Artifacts?
Answer :
Artifacts are spurious echoes which masquerade as real echoes. These are artificial echoes which appear on the screen.
Question 43. What Is The Principle Of Coulter Counter?
Answer :
A platinum electrode is placed inside the orifice tube and a second electrode is submerged into the beaker containing the cell dilution, creating an electrical circuit between the two electrodes.Current will flow from one electrode to the other through the orifice. When the cell suspension is drawn through the orifice, cells will displace their own volume of electrolyte and cause a resistance change, which is converted to a voltage change and is amplified and displayed.
Question 44. Define Systolic And Diastolic Pressure?
Answer :
Systole is the period of contraction of the ventricular muscles during that time blood is pumped into the pulmonary artery and the aorta. Diastole is the period of dilation of the heart chambers as the blood fills the heart. For normal adult the systolic pressure is around 140 mm of Hg and diastolic pressure is around 80 mm of Hg. It is measured using noninvasive blood pressure measuring device called as Sphygmomanometer.
Question 45. What Is Meant By Cell?
Answer :
The basic living unit of the body is cell. The function of organs and other structure of the body are understood by cell organization.
Question 46. Define Transducers?
Answer :
Transducers are defined as a device which when actuated, transforms energy from one form to another. Generally, any physical parameters are converted into electrical form.
Question 47. Define Sensitivity?
Answer :
Sensitivity is defines as the electrical output per unit change in the physical parameter. High sensitivity is generally desirable for a transducer.
Question 48. What Are The Requirements Of Amplifiers Used In Biomedical Recorders?
Answer :
High power gain to activate the pen motor in the display.
An ideal non inverting amplifier to avoid cross over distortion.
Excellent frequency response in the sub audio frequency range
To avoid noise, limited high frequency noise is used.
Question 49. Define PCG ?
Answer :
Phonocardiograph is an instrument used for recording the sounds connected with the sounds connected with the pumping action of the heart. These sounds provide indication for heart rate, rhythmicity.
Question 50. Give The Disadvantage Of Using Surface Electrodes With EMG ?
Answer :
Surface electrodes can be used only for superficial muscles
They are sensitive to electrical activity over too wide area.
Question 51. What Is The Use Of EMG?
Answer :
EMG is used for the measurement of action potentials, either directly from the muscle or from the surface of the body.
Question 52. What Is Hematocrit?
Answer :
The volume of packed red cells is called Hematocrit. It is expressed as a percentage of the total blood volume. It can be used to calculate the mean cell volume (MCV).
Question 53. What Is Fibrin?
Answer :
One of the proteins, fibrinogen, participates in the process of blood clotting and forms thin fibers called fibrin.
Question 54. What Is Korotkoff Sound?
Answer :
When cuff in inflated to a pressure that only partially occludes the brachial artery turbulence is generated in thee blood as it spurts through the tiny arterial opening during each systole. The sounds generated by this turbulence are called korotkoff sounds.
Question 55. What Are The Methods Used To Measure Blood Pressure Is Directly?
Answer :
Catheterization method involving the sensing of blood pressure through a liquid column. In this method the transducers is external to the body and blood pressure is transmitted through a saline solution column in a catheter to this transducers.
This method also involves the placement of transducers through a catheter at the actual site of measurement in the blood stream. Percutaneous methods in which the blood pressure is sensed in the vessel just under the skin by the use of a needle or catheter. Implantation technique in which the transducer is more permanently placed in the blood vessel.