Introduction
At your next checkup, you'll likely get your blood pressure measured. This is for good reason, as blood pressure is widely regarded as one of the most important vital signs in medicine. Elevated values are very common in the United States, and can have major implications on a person's health, harming organs, overall function, and substantially increasing risks to develop future conditions. For this reason, being able to interpret values and staying informed about the risks and causes of blood pressure will continue to play a crucial rule in health in the coming decades.
The Physical Mechanism
Let's consider an example, specifically, inflating the tire of a bike. While you push and pull on the handle, air flows from the pump, through the tubing, and into the tire. In order for the system to work, the air exerts a certain pressure upon the tubing while it's moving through it, dependent upon how much force you're applying.
The key lies in the efficiency of the bike pump, or in our case, the heart. The stronger and healthier a heart is, the more blood it can pump with less effort, reducing the amount of pumps needed and thereby lowering blood pressure within the arteries (in our bike tire example, the tubing).
This explains why world-class athletes have such low resting heart rates, like Usain Bolt, who's resting heart rate is 30 bpm! His heart is so trained from exercise, that it can supply oxygenated blood to his whole body with utter ease. As a result, his arteries are put under very little strain, and remain flexible, undamaged, and healthy.
Systolic and Diastolic Blood Pressure
Blood pressure is reported as a set of 2 measurements, one on top of the other. Although they measure different things, they are both valuable for assessment and are therefore always given together.
The top number measures blood pressure while the heart is in systole, or when it contracts and pushes blood out to the arteries. Thankfully, it's quite appropriately named the systolic blood pressure.
The bottom number, called the diastolic blood pressure, measures your blood pressure while the heart is in diastole, or the phase in which it relaxes, allowing blood to fill the ventricles.
An easy way to differentiate the two is to look at the magnitudes. The systolic blood pressure will always be higher, which makes sense, considering it's being measured while heart is pushing more blood into the arteries.
Diagnosis
There are no obvious symptoms that can indicate if someone has high blood pressure (called hypertension), so the most reliable method is to measure and compare against the guidelines released by the American Heart Association. Here is what you need to know:
Blood Pressure Level | Systolic Blood Pressure | Diastolic Blood Pressure |
Normal | Less than 120 | Less than 80 |
Elevated | 120 - 129 | Less than 80 |
Hypertension Stage 1 | 130 - 139 | 80 - 89 |
Hypertension Stage 2 | Higher than 140 | Higher than 90 |
Hypertensive Crisis Emergency | Higher than 180 | Higher than 120 |
Ongoing Research
The links found between blood pressure and other aspects of heath give us insight into how connected and interdependent our body systems are. Factors like sleep quality, hydration, pain, obesity, diet, and alcohol consumption have all been shown to have significant increasing effects on blood pressure. A 2010 study at the University of Chicago found that loneliness turned out to be an excellent predictor for future hypertension.
Conversely, the effects that a high blood pressure has upon other body systems is equally wide-spanning. Aside from damaging the cardiovascular system (in the form of aneurysms, coronary artery disease, and heart failure), high blood pressure has been proven to cause blindness, sexual dysfunction, kidney failure, and stroke. A 2021 meta-analysis even indicated that prolonged hypertension is closely associated with cognitive impairment.
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