12th Class Biology Biotechnology And Its Applications Diagnostic Instruments

(1) Sphygmomanometer  

(i) Sphygmomanometer, commonly called B.P. Apparatus, is an instrument for measuring blood pressure.

(ii) This instrument consists of a rubber cuff attached by a rubber tube to a compressible hand pump or bulb.

(iii)  Another tube attaches to the cuff and to a column of mercury or pressure dial marked off in millimeters.

(iv) Blood pressure is usually taken in the left brachial artery.

(v) Blood pressure is recorded by giving the systolic pressure and diastolic pressure expressed as millimeters of mercury (mm Hg).

(vi) A healthy young adult male has blood pressure reading of about 120/80 (i.e. 120 mm Hg systolic and 80 mm Hg diastolic).

(vii) The difference between systolic and diastolic pressure is called Pulse pressure.

(viii) Blood pressure often rises normally with age to about 130/90 at age 60.

(ix) Abnormally high blood pressure is known medically as hypertension; abnormally low blood pressure is termed hypotension.

(2) Electrocardiograph

(i) The abbreviation ECG stands for electrocardiogram, a record of myoelectrical changes that immediately precede contraction of heart muscle.

(ii) Electrocardiograph is the instrument used to record ECG.

(iii)  Leads from this instrument are attached to the chest, wrists and ankles using conducting jelly.

(iv) The waves produced in ECG are known as P, Q, R, S and T.

(v) An ECG is helpful for diagnosing pathological disorders of the heart like coronary artery disease, coronary thrombosis, pericarditis, cardiomyopathy and myocarditis.

• Multi-channel monitors measure and display the ECG, blood pressure in various heart chambers and other physiological data.
• Echocardiography is a method of obtaining an image of the structure of heart using ultrasound.
• Doppler echocardiography is a technique which allows the indirect measurement of the flow of velocity as it passes through the heart.

(3) Electroencephalograph

(i) The electrical activity of the exposed animal brain was discovered by Satton in 1875.

(ii) Hans Berger (1929) was the first to record Electro-Encephalo-Gram (EEG).

(iii)  Electroencephalography is done by attaching a number of small electrodes to the scalp.

(iv) The electrodes are connected to an instrument that measures the brain's impulses in microvolts and amplifies them for recording purposes.

(v) Electroencephalography is painless, produces no side-effects and to record it takes about 45 minutes.

(vi) An EEG records the minute electrical impulses produced by the activity of brain.

(vii) EEG is useful to find out whether the person is alert, awake or asleep.

(viii) EEG can help in diagnosing certain conditions such as epilepsy, encephalitis, dementia and brain tumour.

(ix) Electroencephalography can also be used to monitor the condition of patients during surgery and to assess the depth of anaesthesia.

(x) EEG is also used as a test for brain death.

(xi) The weaker magnetic fields from the brain can be studied with the help of SQUID (Super conducting Quantum Interference Device).

(xii) Magnetoencephalography (MET) is useful for studying the disease associated with the brain and spinal cord.