RELAXATION SCIENCE

  DISORDERS OF CIRCULATORY SYSTEM   High Blood Pressure (Hypertension):   Hypertension is the term for blood pressure that is higher than normal (120/80).  In this measurement 120 mm Hg (millimetres of mercury pressure) is the systolic, or pumping, pressure and 80 mm Hg is the diastolic, or resting, pressure.  If repeated checks of blood pressure of an individual is 140/90 (140 over 90) or Schematic plan of blood circulation in human higher, it shows hypertension.  High blood pressure leads to heart diseases and also affects vital organs like brain and kidney.  Coronary Artery Disease (CAD):   Coronary Artery Disease, often referred to as atherosclerosis, affects the vessels that supply blood to the heart muscle.  It is caused by deposits of calcium, fat, cholesterol and fibrous tissues, which makes the lumen of arteries narrower.  Angina:   It is also called ‘ angina pectori s’.  A symptom of acute chest pain appears when no e...

AIR POLLUTION   We are dependent on air for our respiratory needs.  Air pollutants cause injury to all living organisms.  They reduce growth and yield of crops and cause premature death of plants.  Air pollutants also deleteriously affect the respiratory system of humans and of animals.  Harmful effects depend on the concentration of pollutants, duration of exposure and the organism.  Smokestacks of thermal power plants, smelters and other industries release particulate and gaseous air pollutants together with harmless gases, such as nitrogen, oxygen, etc.  These pollutants must be separated/ filtered out before releasing the harmless gases into the atmosphere.  Electrostatic precipitator There are several ways of removing particulate matter; the most widely used of which is the electrostatic precipitator, which can remove over 99 per cent particulate matter present in the exhaust from a thermal power plant.  It has electrode wires that are m...

  Electrocardiograph (ECG)  You are probably familiar with this scene from a typical hospital television show: A patient is hooked up to a monitoring machine that shows voltage traces on a screen and makes the sound “... pip... pip... pip..... peeeeeeeeeeeeeeeeeeeeee” as the patient goes into cardiac arrest.  This type of machine (electro-cardiograph) is used to obtain an electrocardiogram (ECG). ECG is a graphical representation of the electrical activity of the heart during a cardiac cycle.  To obtain a standard ECG, a patient is connected to the machine with three electrical leads (one to each wrist and to the left ankle) that continuously monitor the heart activity.  For a detailed evaluation of the heart’s function, multiple leads are attached to the chest region.  Here, we will talk only about a standard ECG.  Each peak in the ECG is identified with a letter from P to T that corresponds to a specific electrical activity of the heart.  The P-...

 DOUBLE CIRCULATION   The blood flows strictly by a fixed route through Blood Vessels—the arteries and veins.  Basically, each artery and vein consists of three layers: an inner lining of squamous endothelium, the tunica intima, a middle layer of smooth muscle and elastic fibres, the tunica media, and an external layer of fibrous connective tissue with collagen fibres, the tunica externa.  The tunica media is comparatively thin in the veins.  As mentioned earlier, the blood pumped by the right ventricle enters the pulmonary artery, whereas the left ventricle pumps blood into the aorta.  The deoxygenated blood pumped into the pulmonary artery is passed on to the lungs from where the oxygenated blood is carried by the pulmonary veins into the left atrium.  This pathway constitutes the pulmonary circulation. The oxygenated blood entering the aorta is carried by a network of arteries, arterioles and capillaries to the tissues from where the deoxygenated bl...

  RADIOACTIVE WASTES  Initially, nuclear energy was hailed as a non-polluting way for generating electricity.  Later on, it was realised that the use of nuclear energy has two very serious inherent problems.  The first is accidental leakage, as occurred in the Three Mile Island and Chernobyl incidents and the second is safe disposal of radioactive wastes.  Radiation, that is given off by nuclear waste is extremely damaging to biological organisms, because it causes mutations to occur at a very high rate.  At high doses, nuclear radiation is lethal but at lower doses, it creates various disorders, the most frequent of all being cancer.  Therefore, nuclear waste is an extremely potent pollutant and has to be dealt with utmost caution.  It has been recommended that storage of nuclear waste, after sufficient pre-treatment, should be done in suitably shielded containers buried within the rocks, about 500 m deep below the earth’s surface.  However,...