5.7 Blood Pressure | Hypertension | Absolute Temperature Scale | Units | Class 9 | Chemistry

Blood pressure is measured using a pressure gauge. It may be a mercury manometer or some other device. Blood pressure is reported by two values, such as 120/80, which is a normal blood pressure. The first measurement shows the maximum pressure when the heart is pumping. It is called systolic pressure. When the heart is in resting position, pressure decreases and it is the second value called diastolic. Both of these pressures are measured in torr units. Hypertension is because of high blood pressure due to tension and worries in daily life. The usual criterion for hypertension is a blood pressure greater than 140/90. Hypertension raises the level of stress on the heart and on the blood vessels. This stress increases the susceptibility of heart attacks and strokes. Lord Kelvin introduced absolute temperature scale or Kelvin scale. This scal of temperature starts from 0 K or -273.15 °C, which is given the name of absolute zero. It is the temperature at which an ideal gas would have zero volume. As both scales have equal degree range, 100°C therefore, when 0 K equal to -273 °C then 273 K is equal to 0°C as shown in the scale. Body temperature is measured in Fahrenheit scales. Normal body temperature is 98.6 °F, it is equivalent to 37 °C. This temperature is close to average normal atmospheric temperature. In winter atmospheric temperature falls lower than that of our body temperature. According to principle of heat flow, heat flows out from our body and we feel cold. To control this outward flow of heat, we wear black and warm clothes. To maintain body temperature we use dry fruits, tea, coffee and meat etc. Degree sign (°) is used with Celsius scale not with Kelvin scale. Follow us on: FACEBOOK: https://www.facebook.com/AlFarooq.Aca... INSTAGRAM: https://instagram.com/alfarooqacademy... WHATSAPP: 03071070723