What Is Normal Blood Pressure?

Normal blood pressure is vital to life. Without the pressure that forces our blood to flow around the circulatory system, no oxygen or nutrients would be delivered through our arteries to the tissues and organs.

However, blood pressure can become dangerously high, and it can also get too low.

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

What is blood pressure?

Blood pressure is the force that moves blood thru our circulatory system. It is an important force because oxygen and nutrients would not be pushed around our circulatory system to nourish tissues and organs without blood pressure.

Blood pressure is also important because it transports white blood cells and antibodies, as well as hormones like insulin, for immunity.

Fresh blood can pick up harmful waste products of metabolism, such as the carbon dioxide we exhale with every breath and the toxins we clear through our liver and kidneys, which is just as crucial as supplying oxygen and nutrition.

Blood has a number of other characteristics, including temperature. It also contains clotting platelets, which limit blood loss after an accident and are one of our defenses against tissue damage.

What exactly causes blood to exert pressure in our arteries, though? Part of the answer is straightforward: the heart raises blood pressure by forcing blood out when it contracts.

Blood pressure, however, cannot be created solely by the pumping heart.

Ranges

The National Institutes of Health cites normal blood pressure as being below 120 mm Hg systolic and 80 mm Hg diastolic.

However, blood pressure changes naturally, a fact that cardiologists explored while writing about blood pressure variability in NatureTrusted Source in March 2013:

“Blood pressure is characterized by significant short-term fluctuations (beat-to-beat, minute-to-minute, hour-to-hour, and day-to-night changes) that occur within a 24-hour period, as well as long-term fluctuations that occur over longer periods of time (days, weeks, months, seasons, and even years).”

The rules of thumb According to every 20 mm Hg increase in blood pressure above 115/75 mm Hg doubles the risk of cardiovascular disease.

In November 2017, Trusted Source updated the overall guidelines for high blood pressure. They make it possible to intervene earlier.

The American Heart Association (AHA) has recommended that persons with high blood pressure be treated at 130/80 mm Hg instead of 140/90 mm Hg since 2017.

They also removed the “prehypertension” category between 120-139 and 80-89 mm Hg. A blood pressure reading of 140/90 mm Hg now qualifies 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

In these new guidelines, the AHA also advises that doctors should only prescribe medication in cases of a previous heart attack or stroke, or in the presence of risk factors for these conditions, such as age, a diabetes mellitus diagnosis, or chronic kidney disease.

Treatment at the earlier stages should instead come mainly through lifestyle changes.

Function

Blood has a ‘flow,’ and arteries are ‘pipes,’ analogous to a very sophisticated sort of plumbing. Our blood flow is caused by a fundamental physics law, which also applies to a garden hose pipe.

A difference in pressure causes blood to circulate through our bodies.

Our blood pressure is highest as it leaves our heart and enters the aorta, and it is lowest when it reaches the end of its journey through progressively smaller branches of arteries. Blood circulates around our body because of the pressure differential.

Blood pressure is affected by arteries in the same way as the physical qualities of a garden hose pipe affect water pressure. The pressure at the spot grows as the pipe is constricted.

Without the elastic nature of the artery walls, for example, the pressure of the blood would fall away more quickly as it is pumped from the heart.

While the heart creates the maximum pressure, the properties of the arteries are just as important to maintaining it and allowing blood to flow throughout the body.

The condition of the arteries affects blood pressure and flow, and narrowing of the arteries can eventually block the supply altogether, leading to dangerous conditions including stroke and heart attack.

Measurement

The device used to measure blood pressure is a sphygmomanometer, it consists of a rubber armband – the cuff that is inflated by hand or machine pump.

Once the cuff is inflated enough to stop the pulse, a reading is taken from a trusted source, either electronically or on an analog dial.

Readings

A stethoscope identifies the precise point when the pulse sound returns and the pressure of the cuff is slowly released. Using the stethoscope enables the person measuring the blood pressure to listen out for two specific points.

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

The systolic pressure is the higher figure caused by the heart’s contraction, while the diastolic number is the lower pressure in the arteries during the brief “resting” period between heartbeats.

Tips

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 alcoholic drink a day.

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

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