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What is a normal blood pressure?

Normal blood pressure is of vital importance to life. No oxygen or nutrients would be distributed to the tissues and organs through our arteries without the pressure that causes our blood to circulate around the circulatory system.

Blood pressure can get dangerously high, though, and it can get too low too.

We will discuss what blood pressure is, how it is measured, and what the measurements mean for our health in this article.

What is blood pressure?

Blood pressure is the driving power of the blood from our circulatory system.

It is an important force because no blood pressure would push oxygen and nutrients around our circulatory system to nourish tissues and organs.

Blood pressure is also vital since it provides immunity for white blood cells and antibodies, and hormones such as insulin.

Just as important as supplying oxygen and nutrients, the fresh blood that is supplied is capable of storing metabolism toxic waste products including the carbon dioxide that we exhale with every breath, and the toxins that we flush through our liver and kidneys.

Just as important as supplying oxygen and nutrients, the fresh blood that is supplied is capable of storing metabolism toxic waste products including the carbon dioxide that we exhale with every breath, and the toxins that we flush from our liver and kidneys.

Blood itself has several other properties including temperature. It also carries one of our defenses against damage to the tissue, the clotting platelets which prevent blood loss after injury.

But what exactly does blood cause our arteries to exert a pressure? Part of the answer is simple-by forcing blood out when it contracts with every heartbeat, the heart creates blood pressure. But blood pressure cannot be created solely by the pumping heart.


Our circulation is similar to a highly sophisticated form of plumbing-blood has’ flow’ and arteries are’ pipes.’ A fundamental law of physics gives rise to our blood flow and this law also applies in a garden hose pipe.

Blood flows through our body because of a difference in pressure.

At the beginning of its journey our blood pressure is highest from our heart-when it reaches the aorta-and it is lowest at the end of its path through progressively smaller branches of arteries. The disparity in pressure is what allows blood to flow across our bodies.

Arteries have a similar effect on blood friction to the physical properties of a garden hose pipe which affects water pressure. Constricting the pipe at the point of constriction increases the pressure.

For example, without the elastic ity of the artery walls, blood pressure can drop faster as it’s pumped from the heart.

While the heart produces the maximum pressure, it is just as important to maintain the properties of the arteries and to allow blood to flow through the whole body.

Artery condition affects blood pressure and flow, and artery narrowing will ultimately obstruct the supply entirely, leading to hazardous conditions like stroke and heart attack.


The device used to measure blood pressure is a sphygmomanometer, it consists of a rubber bracelet-the manual or machine pump-inflated cuff.

Once the cuff is sufficiently inflated to interrupt the pulse, a reading is taken either electronically, or on an analog dial.

The reading is measured by the pressure required to move mercury round a tube against gravity. This is the reason the unit millimeters of mercury, abbreviated to mm Hg, are used to measure pressure.


A stethoscope detects the exact point when the pulse sound returns, and gradually removes the cuff strain. Using the stethoscope allows the person monitoring the blood pressure to listen for two particular points.

Blood pressure readings are composed of two figures-first the systolic pressure and second the diastolic pressure. The reading is given as 140 over 90 mm Hg for example.

The systolic pressure is the higher figure caused by the contraction of the heart, while the diastolic number is the lower pressure in the arteries during the short heartbeat’ rest’ period.


The National Institutes of Health report normal blood pressure to be below systolic Hg 120 mm and diastolic Hg 80 mm.

Naturally, however, blood pressure varies, a fact that cardiologists discussed in March 2013 when writing about the increase of blood pressure of Nature:

Blood pressure is distinguished by significant short-term variations occurring within a 24-hour cycle (beat-to-beat, minute-to-minute, hour-to-hour and day-to-night changes) and also by longer-term fluctuations occurring over longer periods of time (days, weeks, months, seasons and even years).

The Guidelines state that every 20/10 mm Hg rise doubles the risk of cardiovascular disease for blood pressure above a level of 115/75 mm Hg.

Of November 2017 an update was received to the general guidelines for high blood pressure. They permit earlier interference.

The American Heart Association (AHA) has been advising since 2017 that people with high blood pressure should be treated at 130/80 mm Hg, rather than 140/90 mm Hg.

Also, they removed the category “prehypertension” between 120-139/80-89 mm Hg. A level of 140/90 mm Hg of blood pressure currently counts as stage II hypertension and not stage I, as it used to be.

This category now forms two separate ranges:

  • elevated blood pressure, from 120-129/less than 80 mm Hg
  • stage I hypertension, from 130-139/80-89 mm Hg

The AHA also recommends in these new guidelines that physicians should only prescribe medicine in cases of an previous heart attack or stroke, or in the presence of risk factors for such conditions, such as age, diabetes mellitus, or chronic kidney disease.

Instead, counseling at the earlier stages may come primarily from lifestyle changes.


The guidelines for doctors list the following measures patients can take to help keep a healthy blood pressure:

  • Keep a healthy body weight.
  • Eat a diet rich in fruits, vegetables, and low-fat dairy products.
  • Cut down on sodium, or salt, in the diet.
  • Take regular aerobic exercise, such as brisk walking, for at least 30 minutes a day, most days of the week.
  • Moderate alcohol intake. Men should drink fewer than two alcoholic beverages a day for men. Women and men with a lower body weight should consume a maximum of one alcohol drink a day.

Taking these steps can reduce the risk of health problems further down the line.

Chukwuebuka Martins

Chukwuebuka MartinsĀ is a writer, researcher, and health enthusiast who specializes in human physiology. He takes great pleasure in penning informative articles on many aspects of physical wellness, which he then thoroughly enjoys sharing to the general public.

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