Systolic Blood Pressure
What is the systolic blood pressure number that`s displayed on your monitor? Listen to your heart beat!
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The heart rests just for a split second, then it contracts and a surging, high volume of blood gushes into the arteries. This causes the pressure in your arteries to increase which is measured as millimeters of mercury (mmHg) and is the top number.
Immediately after this the heart goes into rest mode again while the blood flows from the atria into the ventricles. At this point the pressure is at it`s lowest. The Diastolic blood pressure.
SBP when it is over 120 mmHg is classed as pre-hypertensive. When it is 140 mmHg and above it comes into the hypertensive categories stage 1 and 2. This is the number your doctor will be watching in general because blood pressure that is persistently too high causes damage to the arteries in the heart and elsewhere in the cardiovascular system.
The Hearts Natural Pacemaker
But what is it that causes the lower ventricle chambers to contract? It is the work of a pacemaker, a natural one.
This pacemaker (the Sinoatrial Node) is located in the upper right corner of the right atrium and inside it contains the trigger, special self-powered cells that send waves of electricity to make the heart muscle contract.
In the first, split second phase it causes the atria muscles to contract and pressure the valves to open, letting the blood into the ventricles. Then in the next split second the wave triggers another node (the atrioventricular node) on the opposite wall in the same right atrium to send a charge to the muscles down the sides of the ventricles to contract and push the blood into the arteries at high pressure.
Yes, the heart is a wonderful pump indeed! In fact the speed in which the heart performs each cycle or beat nearly caused William Harvey, the English physician who discovered that the heart circulated the blood around the body, to believe that the movement of the heart was only to be comprehended by God. For he could neither rightly perceive at first when the systole and when the diastole took place by reason of the rapidity of the movement.
Isolated Systolic Hypertension
You may have a high systolic blood pressure even although the diastolic remains normal. It usually occurs in older people with HBP and is quite common.
Systolic Heart Failure
This condition is caused by several underlying cardiovascular problems. But the commonest causes are high blood pressure and coronary artery disease.
What happens is that the muscles in the ventricles become weak or damaged. They can`t manage to to contract enough to pump the blood around the body.