What is Blood Pressure and how it is measured?
We all know that blood is a red colour pigment which circulates in our body. It is red in colour because it contains red pigment haemoglobin. It consists of plasma, red blood cells, white blood cells and platelets. Blood helps in transportation of substances like oxygen, carbon dioxide, digested food etc. from one part of the body to the other. It also protects us from diseases and also regulates blood temperature.
When heart beats, it pumps blood round the body to give energy and oxygen. As, blood moves in the body, it pushes against the sides of the blood vessels. Strength of pushing blood vessels generates pressure which is known as blood pressure. So, we can define that Blood Pressure is the pressure at which blood is pumped around the body by the heart. If blood pressure is high that is extra strain is produced on the arteries or heart and may lead to heart attack. So, to maintain blood pressure normal is very necessary.
What is normal blood pressure?
In the form of two values the blood pressure is always expressed i.e. systolic pressure and diastolic pressure.
Now question is what is systole and diastole?
Heart pumps blood and during this process it contracts and expand. The phase of the heart beat when heart contracts and pumps the blood into arteries is called systole and the phase of heart beat when heart expands or relax and allows the chambers to fill with blood is called diastole.
During contraction phase, the maximum pressure at which blood leaves the heart through the main artery is called systolic pressure. During the relaxation or expansion phase of the heart the minimum pressure of the arteries is called diastolic pressure.
Systolic pressure is 120 mm Hg
Diastolic Pressure is 80 mm Hg
Therefore, Normal Blood pressure is 120/80 but this varies from person to person and from time to time.
Do you know what is high blood pressure?
High blood pressure is known as hypertension. It is caused by the constriction of arteries or arterioles which results in increased resistance to blood flow. It may lead to the rupturing of arteries and internal bleeding. It also leads to various health problems.
How Blood Pressure is measured?
Blood Pressure is measured by an instrument known as sphygmomanometer. There are some steps for measuring blood pressure :
- Firstly, a rubber cuff is wrapped around the person’s arm whose blood pressure is to be measured. Then, rubber cuff is inflated by pumping air at a pressure of about 200 mm Hg to the brachial artery. This pressure you can see it in the instrument sphygmomanometer. No sound is heard when stethoscope is placed on the artery of the arm.
- Now, the rubber cuff pressure is reduced by deflating it and stethoscope is still placed on the artery. The cuff pressure when heart beat is first heard as a soft tapping sound through the stethoscope gives us the systolic pressure.
- When the rubber cuff pressure is further reduced by deflating it more and more. The cuff pressure when the tapping sound in stethoscope just disappears and gives the diastolic pressure.
In this way blood pressure is measured. It can also be explained: When high pressure of 200 mm Hg is applied to the arm by the rubber cuff, brachial artery gets closed and no blood flows in it. As, a result no tapping sound is heard in the stethoscope placed on the artery because blood is not flowing. But when rubber cuff pressure is reduced and becomes equal to the systolic pressure, blood slightly starts flowing through arteries and the first sound heard on the stethoscope. Further, when rubber cuff pressure is reduced and becomes equal to diastolic pressure, artery opens up fully, blood flows and the sound finally disappears.