What is it?
High blood pressure, or hypertension, is a medical condition in which blood pressure is elevated for a long period of time. Hypertension causes rarely symptoms in itself, but in the long term it can have serious consequences including coronary artery disease, stroke, and heart failure.
Blood pressure is measured during both the “rest” and the “pumping” periods of the heart. These are called diastole and systole respectively, and this is why the measurements always show a smaller and a larger number. Blood pressure is classified as high, when its values persist over 90/140.
Around 26% of the world’s adult population have hypertension. These numbers vary a lot globally, though: in rural India the number is around 5%, while in Poland it is around 70%. It is believed that in 2010, hypertension was a factor in 18% of all deaths.
What causes it?
Although genes have some effect, most cases of hypertension are the result of environmental factors. Blood pressure rises naturally as we age, so older people are more susceptible for hypertension. Other important factors include eating a lot of salt, not exercising, being obese. drinking lots of alcohol, smoking, and not getting enough sleep.
In around 5% of cases, hypertension is the result of an underlying condition, such as kidney disease or diabetes.
What happens during it?
Blood pressure depends both on the rate of blood flow and the resistance of the arteries. Most cases of hypertension occur because of an increased resistance. The arteries exert more force on the blood, and the heart needs to compensate by pumping more blood so that the forces balance each other out and blood gets delivered everywhere.
Life is hard. Even on the cellular level. This is why our bodies need to make sure that the concentration of our blood, for example, remains the same. When we eat too much salt, or when we have kidney disease or diabetes, we have an abnormally large amount of ions and small molecules in our blood. Our bodies try to compensate this rise in concentration by keeping more water in. (This is why you feel puffy the morning after you’ve eaten a salty pizza for dinner.) This is not all, however: when our arteries notice that the blood pushes them with a bigger force than before, they grow bigger and stronger. This increases the resistance, which increases the output, which increases the resistance… A vicious circle has soon formed.
The other lifestyle factors causing hypertension are similar to this process. Obesity, for example, makes it harder for the blood to circulate around the body, and the heart must make an increased effort. Smoking, on the other hand, makes arteries stiff by causing the heart pump more blood and by directly affecting the artery walls.
How can it be treated?
Hypertension can most often be effectively prevented and treated by minimizing exposure to the mentioned risk factors. If the person has, however, a high risk for having a stroke or a heart attack, medication can be used. These drugs usually make the arteries relax or widen.
Sources: https://en.wikipedia.org/wiki/Hypertension, https://en.wikipedia.org/wiki/Pathophysiology_of_hypertension, http://www.nhs.uk/Conditions/Blood-pressure-(high)/Pages/Treatment.aspx, http://www.bloodpressureuk.org/microsites/salt/Home/Whysaltisbad/Saltseffects, https://www.sharecare.com/health/high-blood-pressure/why-cause-high-blood-pressure