Blood Pressure Gauge


The human heart is an amazing pump, it works reliably for decades, and it safely pumps blood—one of the trickiest and most sophisticated liquids around. In the same way, blood vessels are pipes, they take the output from the pump and distribute it throughout the body. The blood pressure is measured by a device known as blood pressure gauge that measures the performance of the pump and the pipes.

A blood pressure gauge, also referred to as a “sphygmomanometer”, is a device used to measure blood pressure, composed of an inflatable cuff to restrict blood flow, and a mercury or mechanical manometer to measure the pressure. It is always used in conjunction with a means to determine at what pressure blood flow starts, and at what pressure it is unimpeded. Manual sphygmomanometers are used in conjunction with a stethoscope. The usual unit of measurement of blood pressure is millimeters of mercury (mmHg) as measured directly by a manual sphygmomanometer.

By observing the mercury in the column while releasing the air pressure with a control valve, one can read the values of the blood pressure in mmHg. The peak pressure in the arteries during the cardiac cycle is the systolic pressure, and the lowest pressure—at the resting phase of the cardiac cycle—is the diastolic pressure. A stethoscope is used in the auscultatory method. Systolic pressure is identified with the first of the continuous Korotkoff sounds. Diastolic pressure is identified at the moment the Korotkoff sounds disappear.

To explain the process in a simpler way, we may say that there are two numbers in a blood pressure reading: systolic and diastolic pressure. For example, a typical reading might be 120/80. When the doctor puts the cuff around your arm and pumps it up, what he/she is doing is cutting off the blood flow with the pressure exerted by the cuff. As the pressure in the cuff is released, blood starts flowing again and the doctor can hear the flow in the stethoscope.

The number at which blood starts flowing (120) is the measure of the maximum output pressure of the heart (systolic reading). The doctor continues releasing the pressure on the cuff and listens until there is no sound. That number (80) indicates the pressure in the system when the heart is relaxed (diastolic reading).

Measurement of the blood pressure is carried out in the diagnosis and treatment of hypertension (high blood pressure), and in many other healthcare scenarios. If the numbers are too high, it means that the heart has to work too hard because of restrictions in the pipes. Certain hormones, like adrenaline, which is released when you are under stress, cause certain blood vessels to constrict, and this raises your blood pressure.

If you are under constant stress, your blood pressure goes up, and it means that your heart has to work too hard. Other things that can increase the blood pressure include deposits in the pipes and a loss of elasticity as the blood vessels age. High blood pressure can cause the heart to fail from working too hard, or it can cause kidney failure from too much pressure.


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