Hypertension (Blood pressure) is the force exerted by the blood against the walls of blood vessels,and the force depends on the cardiac out put.
The blood flowing inside vessels exerts a force against the walls - this is hypertension (blood pressure).
More information on the biology and physics of normal blood pressure is available, along with details of how blood pressure is measured, what normal measurements look like, and how they change with age and exercise.
Hypertension(Blood pressure) is defined as having a blood pressure higher than 140 over 90 mmHg, with a consensus across medical guidelines.1,5
This means the systolic reading (the pressure as the heart pumps blood around the body) is over 140 mmHg (millimeters of mercury) and/or the diastolic reading (as the heart relaxes and refills with blood) is over 90 mmHg.
This threshold has been set to define hypertension (blood pressure) for clinical convenience as patients experience benefits once they bring their blood pressure below this level.
However, medical experts consider hypertension (blood pressure) as having a continuous relationship to cardiovascular health.1,6 They believe that, to a point, the lower the blood pressure the better (down to levels of 115-110 mmHg systolic, and 75-70 mmHg diastolic).
This view has led the American Heart Association (AHA), for example, to define the following ranges of hypertension (blood pressure) (in mmHg):
Normal blood pressure is below 120 systolic and below 80 diastolic
Prehypertension is 120-139 systolic or 80-89 diastolic
Stage 1 high hypertension (blood pressure) is 140-159 systolic or 90-99 diastolic
Stage 2 highhypertension (blood pressure) is 160 or higher systolic or 100 or higher diastolic
Hypertensive crisis (a medical emergency) is whenhypertension( blood pressure) is above 180 systolic or above 110 diastolic.
Causes of hypertension
As acute stress, intense exercise and other factors can briefly elevate blood pressure even in people whose blood pressure is normal, a diagnosis of hypertension requires several readings showing high blood pressure over time.
Having high blood pressure for a short amount of time is a normal physiological response to many situations. However, a systolic reading of 180 mmHg or higher OR a diastolic reading of 110 mmHG or higher could be a sign of a hypertensive crisis that warrants immediate medical attention.
Anyone who gets such a reading when testing their own blood pressure should wait a couple of minutes and repeat the test. If the reading remains at that level or increases, seek emergency medical treatment (call an ambulance or have someone drive you to the hospital immediately.
Blood pressure does vary throughout the day, lowering during sleep and rising on awakening. It also rises in response to excitement, anxiety and physical activity.
Blood pressure also increases steadily with age as arteries become stiffer and narrower due to plaque build-up. Vascular and heart disease also contribute to rising blood pressure in older adults, and a high systolic reading is a major risk factor for cardiovascular disease in adults over 50 years old.
The disease burden of high blood pressure is a growing problem worldwide, in part because of a rapidly aging population. Other key contributors include lifestyle factors, such as, Physical inactivity, A salt-rich diet associated with processed and fatty foods, Alcohol and tobacco use.
Certain diseases and medications (as described below) can cause high blood pressure, and there are a number of general risk factors for hypertension, including:[abdominal obesity]
Obesity is a risk factor for high blood pressure and other cardiovascular conditions.
Age - everyone is at greater risk of high blood pressure as they get older. Prevalence of hypertension is higher in people over 60 years of age
Race - African-American adults are at higher risk than white or Hispanic American adults
Size - being overweight or obese is a key risk factor for hypertension
Sex - males and females have different risk profiles. While lifetime risk is the same for everybody, men are more prone to hypertension at a younger age and women have a higher rate of hypertension at older ages
Lifestyle - greater intake of dietary salt, excessive alcohol, low dietary potassium, and physical inactivity all contribute to an increased risk of hypertension.
Other risk factors include a family history of the disease, and chronic, poorly managed stress.
Specific causes of hypertension
High blood pressure that is not caused by another condition or disease is termed primary hypertension (or essential hypertension). This is more common than secondary hypertension, which has an identified cause such as chronic kidney disease.
Primary hypertension is unlikely to have a specific cause but is instead usually a result of multiple factors, including blood plasma volume and activity of the renin-angiotensin system, the hormonal regulator of blood volume and pressure. Primary hypertension is also influenced by environmental factors, including lifestyle-related issues as outlined above.
Specific causes of hypertension (Blood Pressure)
Secondary hypertension(blood pressure) has specific causes - that is, it is secondary to another problem. One example, now thought to be one of the most common causes of treatment-resistant hypertension, is primary aldosteronism, a hormone disorder causing an imbalance between potassium and sodium levels, thus leading to high blood pressure.
Primary aldosteronism may account for some 5-15% of cases of hypertension. It is important that physicians determine if the condition is caused by hyperplasia of the adrenal gland(s) or an adrenal gland tumor as treatments differ between the two.
Common reversible causes are excessive intake of alcohol and use of oral contraceptives, which can cause a slight rise in blood pressure; hormone therapy for menopause is also a culprit. Secondary hypertension(blood pressure) can also result from:
Diabetes (both due to kidney problems and nerve damage), Kidney disease, Pheochromocytoma (a cancer), Cushing syndrome (which can be caused by use of corticosteroid drugs), Congenital adrenal hyperplasia (disorder of the adrenal glands, which secrete the hormone cortisol), Hyperthyroidism (overactive thyroid gland), Hyperparathyroidism (which affects calcium and phosphorous levels), Pregnancy, Sleep apnea, Obesity.
Symptoms of hypertension
High blood pressure itself is usually asymptomatic, meaning that patients do not experience any direct symptoms of the condition. This is why hypertension is often referred to as "the silent killer," as it can quietly causes damage to the cardiovascular system.
Hypertension can also lead to problems in the organs affected by high blood pressure. Long-term hypertension can cause complications through arteriosclerosis, where the formation of plaques results in narrowing of blood vessels.
The complications associated with hypertension-related arteriosclerosis can include:
An enlarged or weakened heart, to a point where it may fail to pump enough blood (heart failure)
Aneurysm - an abnormal bulge in the wall of an artery (which can burst, causing severe bleeding and, in some cases, death)
Blood vessel narrowing - in the kidneys this can lead to possible kidney failure; in the heart, brain and legs, this can lead to heart attack, stroke or the need for amputation, respectively
Blood vessels in the eyes my rupture or bleed, leading to vision problems or blindness (hypertensive retinopathies - classified by worsening grades one through four).