New Delhi, October 25, 2023: Blood pressure is the force that moves blood through the circulatory system. It is an important force because oxygen and nutrients would not be pushed around the circulatory system to nourish tissues and organs without blood pressure.
Blood pressure is also vital because it delivers white blood cells and antibodies for immunity and hormones such as insulin.
Just as important as providing oxygen and nutrients, the fresh blood that gets delivered is able to pick up the toxic waste products of metabolism, including the carbon dioxide we exhale with every breath and the toxins we clear through the liver and kidneys.
Blood itself carries a number of other properties, including its temperature. It also carries one of the defenses against tissue damage, the clotting platelets that prevent blood loss following injury.
But what exactly causes blood to exert pressure in the arteries? Part of the answer is simple — the heart creates blood pressure by forcing out blood when it contracts with every heartbeat. Blood pressure, however, cannot be created solely by a pumping heart.
Both numbers in a blood pressure reading are essential for diagnosing and treating high blood pressure, doctors primarily focus on the top number, also known as systolic pressure.
Systolic pressure reflects the force produced by the heart when it pumps blood out to the body, while diastolic blood pressure (the bottom number) is the pressure in your blood vessels when the heart is at rest.
Over the years, research has found that both numbers are equally important in monitoring heart health. However, most studies show a greater risk of stroke and heart disease related to higher systolic pressures compared with elevated diastolic pressures. That’s especially true in people ages 50 and older, which is why doctors tend to monitor the top number more closely. The reason for the difference in risk may be related to the force put on the arteries when blood rushes out of the heart.
The American Heart Association now defines high blood pressure as 130/80 mm Hg or higher. The new guidelines recommend you check your blood pressure often, ideally with a home monitor, to help your doctor determine if you need to make lifestyle changes, begin medication, or alter your current therapy.
High blood pressure chart
| Category | Systolic | and/or | Diastolic |
|---|---|---|---|
| Normal | < 120 mm Hg | and | < 80 mm Hg |
| Elevated (at risk, or prehypertension) | 120-129 mm Hg | and | < 80 mm Hg |
| Hypertension stage 1 | 130-139 mm Hg | or | 80-89 mm Hg |
| Hypertension stage 2 | > 140 mm Hg | or | > 90 mm Hg |
| Hypertensive crisis (emergency situation) | > 180 mm Hg | and/or | > 120 mm Hg |
The function of blood pressure in the body
Circulation is similar to a highly sophisticated form of plumbing — blood has “flow,” and arteries are “pipes.” A basic law of physics gives rise to blood flow, and this law also applies in a garden hose pipe.
Blood flows through the body because of a difference in pressure.
Blood pressure is highest at the start of its journey from the heart — when it enters the aorta — and it is lowest at the end of its journey along progressively smaller branches of arteries. That pressure difference is what causes blood to flow.
Arteries affect blood pressure in a similar way to the physical properties of a garden hose pipe affecting water pressure. Constricting the pipe increases pressure at the point of constriction.
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.
Blood pressure 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 either electronically or on an analog dial.
The reading is expressed in terms of the pressure it takes to move mercury around a tube against gravity. This is the reason for pressure being measured using the unit millimeters of mercury, abbreviated to mm Hg.
Measuring blood pressure typically does not cause any pain or discomfort. However, it can temporarily feel tight around the arm.
Blood pressure 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 for preventing high blood pressure
- Maintain a healthy body weight based on a doctor’s recommendation.
- Eat a balanced diet rich in fruits and vegetables.
- Cut down on sodium, or salt, in the diet.
- Regularly engage in physical activity, such as brisk walking, for at least 30 minutes a day, most days of the week, if possible.
- Manage stress.
- Moderate alcohol intake. Men should drink fewer than two alcoholic beverages a day. Women and men with a lower body weight should consume a maximum of one alcoholic drink a day.
- Quit smoking.
- Work with a doctor to manage all prescriptions properly.
Low blood pressure concerns
Low blood pressure, or hypotension, is not typically as worrisome as high blood pressure. However, it can still indicate health issues.
A person with a blood pressure reading of less than 90/60 mm HgTrusted Source is considered to have low blood pressure. The AHATrusted Source has stated that doctors do not usually consider this a problem unless other symptoms exist alongside it.
These underlying issues could include internal bleeding, heart disease, pregnancy, some medications, among other situations.
If a person experiences other symptoms, they should speak with their doctor to address any underlying conditions.
Takeaway
Blood pressure is essential to the body. However, it can become too high or too low. A blood pressure reading that is too high is called hypertension, or high blood pressure. This can cause a number of health issues and should be monitored with a doctor.
High blood pressure can be managed, especially with early intervention and some lifestyle adjustments.
