Have you ever wondered why the medical entrances in India list having physics as a subject is grades eleven and twelve as a requirement? Has the PCB (Physics, Chemistry and Biology) combination ever befuddled your brain? Biology and Chemistry automatically fit in the puzzle however; physics always seems like a misfit, an extra puzzle piece, when it comes to being eligible
for a medical entrance examination.
The question to be asked here is – “What was the purpose behind listing physics as a requirement?” Well, it was obviously a well thought out decision. Let us take a look at how Physics fits into the puzzle without being an extra piece.
First, we need to know what ‘Medical Physics’ is. Medical physics is the application of theories, concepts and methods in physics to the field of medicine and healthcare (the definition has been taken from the google dictionary). As the name suggests, the subject of Physics is obviously indispensable in the medical world. We unconsciously use various concepts of Physics while understanding the human body. For example, we apply the concepts of physics to understand one of the most important organs of the human body – the heart. The ECG or the Electrocardiogram waveform is used to check and detect any problem with the electrical activity of the heart. The electrical activity is read by the ECG and translated into a set of line tracings on paper which are called waves. The principle that this graph works on is an electronic amplifier which consists of two terminals – a non-inverting and an inverting input terminal. The output voltage is proportional to the difference between the voltages supplied at these two terminals, and hence this is represented as:
‘Output voltage = Gain of amplifier (voltage at non-inverting input terminal – voltage at inverting input terminal)’
Now it would not take a genius to see the clear and direct application of physics in this process.
Another interesting example of the application of physics in medicine is its use in the treatment of diseases. For example, ‘defibrillation’ is a treatment for a deadly disease known as cardiac dysrhythmias. This involves using a defibrillator to give mild therapeutic electrical energy to the affected heart area in order to depolarize the critical mass of the heart muscles and hence reverse dysrhythmias. Defibrillation was first demonstrated by two physiologists namely Batelli and Prevost in 1899. They discovered this while delivering small electric shocks to dogs that induced ventricular fibrillation in them. Later they realized that increasing the intensity causes reversal of the same.
Physics is, without a doubt, a very important aspect of medicine and healthcare. The magnification used in the microscopes to critically analyze microscopic things and even the principle with which the X-radiology and PET screening were introduced, involve physics. The examples discussed in this article are just a few amongst the many.
Hence, it is probably time to rethink and give this subject its due importance. Next time, a medical student whines about the irrelevance oh physics in his field of interest, he probably needs to check his facts again. Physics indeed fits perfectly in this brilliant puzzle.