Human Anatomy and Physiology : V. Circulatory System Part-I

• Systolic pressure:
  This is the peak pressure in your arteries when your heart beats and pumps blood into them.

• Diastolic pressure:
  This is the pressure in your arteries when your heart is at rest between beats.

• Normal blood pressure:
  For most adults, a blood pressure reading less than 120/80 mmHg is considered normal.

• Elevated blood pressure:
  A systolic pressure between 120 and 129 mmHg, with a diastolic pressure less than 80 mmHg, is considered elevated.

• Hypertension (high blood pressure):
  Hypertension is diagnosed when blood pressure consistently measures 130/80 mmHg or higher.

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 is just starting and at what pressure it is unimpeded. Manual sphygmomanometers are used in conjunction with a stethoscope.

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 is just starting and at what pressure it is unimpeded. Manual sphygmomanometers are used in conjunction with a stethoscope.

'Hg' is a symbol of Mercury, a chemical element. It is used in thermometers, barometers, sphygmomanometers and other devices. A sphygmomanometer is a device used to measure blood pressure. The person's blood pressure is measured in millimeters of mercury (mmHg). Normal blood pressure of human body is 120/80 mmHg.

The causes of high blood pressure are not known, but several factors and conditions may play a role in its development, including: Smoking, being overweight or obese, lack of physical activity, too much salt in the diet, too much alcohol consumption (more than 1 to 2 drinks per day), stress, older age, genetics, family history of high blood pressure, chronic kidney disease, adrenal and thyroid disorders etc.

The normal atmospheric pressure is 760 mm of Hg. But the normal human blood pressure is around 120/80 mmHg only. Actually when a doctor measures our blood pressure the measurement is done with respect to atmospheric pressure. This means that our blood pressure 120mm Hg more than that of atmospheric pressure of that place. On the other hand atmospheric pressure is measured with respect of vacuum, so the actual blood pressure of our body will be 760+120 = 880 mm Hg with respect to vacuum.

Karl Landsteiner was an Austrian biologist and physician. He is noted for having first distinguished the main blood groups in 1900, having developed the modern system of classification of blood groups from his identification of the presence of agglutinins in the blood and having identified with Alexander S. Wiener, the Rhesus (Rh) Factor in 1937 (which was believed to be a similar antigen found in rhesus monkey red blood cells), thus enabling physicians to transfuse blood without endangering the patient’s life.

Karl Landsteiner was an Austrian biologist and physician. He is noted for having first distinguished the main blood groups in 1900, having developed the modern system of classification of blood groups from his identification of the presence of agglutinins in the blood and having identified with Alexander S. Wiener, the Rhesus (Rh) Factor in 1937 (which was believed to be a similar antigen found in rhesus monkey red blood cells), thus enabling physicians to transfuse blood without endangering the patient’s life.

Agglutinogen is an antigen that causes the formation of agglutinins in the body and leads to agglutination, such as haemagglutination, which involves red blood cells (RBCs). The kind of agglutinogens present on the red blood cells helps determine the blood type of a person. If a person has blood type A, then the red blood cells exhibit agglutinogens A or antigens A. If the blood is of type B, the agglutinogens present are of type B. If the blood is of type AB, then both agglutinogens A and B are present. In blood type O, there are no agglutinogens on the surface of the red blood cells.