What is Blood Pressure?
Blood pressure is the pressure of the circulating blood against the walls of the blood vessels. Blood pressure is measured using two values, the systolic pressure and the diastolic value. Your heart pushes blood through your arteries by contracting and relaxing. When your heart contracts, it pumps blood through your body. This is the systolic pressure. When your heart relaxes between beats, your blood pressure is at its lowest. This is the diastolic pressure. A blood pressure reading consists of two numbers. The first number is the systolic pressure and the second value is the diastolic pressure. Blood pressure is measured in millimeters of mercury. A healthy blood pressure is 120/80, read as 120 over 80, 120 being the systolic pressure and 80 the diastolic value.
Your blood pressure is not the same all over the body, it varies from place to place. Both the systolic and diastolic pressures vary along the different arteries of your body. The pressure in the brachial artery of the forearm serves as the standard. When measuring the blood pressure with a cuff, the cuff must be placed at heart level. This is important since the blood pressure will be greater below heart level and lower above the heart level. Blood pressure at head height is roughly 35 mm Hg less than at heart level. At ground level the blood pressure can be 100 mm Hg higher than at heart level.
Blood pressure fluctuates during the day, changes of 25% is normal. A lot of things can affect your blood pressure. Anger and stress are well known for increasing blood pressure. Just a short walk will increase your blood pressure. But how much your blood pressure will increase depends on a lot of things and varies from person to person. Despite a lot of research, no one has been able to pinpoint the factors that increase or decrease blood pressure. A number of likely causes of hypertension (high blood pressure) have been identified though, such as stress and overweight.
While high blood pressure has defined values, low blood pressure has never been clearly defined. To some extent this is because low blood pressure is in most cases not a major health issue. Some research indicates that chronic low blood pressure can be an indication of other health problems so a medical check-up can be a good idea. What is dangerous, is sudden swings between high and low blood pressure. They can cause interruptions in the blood supply to the heart, the kidneys and the brain.
Note that blood circulation and blood pressure are two different things. High blood pressure does not automatically imply poor blood circulation. It is quite possible to have low blood pressure and poor blood circulation, or for that matter high blood pressure and poor blood circulation.
