What is hypertension?
A consistent blood pressure is necessary in the delivery of blood to the organs of the body. Adequate blood pressure ensures that oxygen within the blood is delivered to tissues. One’s blood pressure depends on a complex interaction of many factors:
- Kidneys: The kidneys can maintain a normal pressure by altering how much urine is excreted. Additionally, special sensors called “baroreceptors” within the kidneys can sense high or low blood pressure and release certain hormones that can increase the blood pressure by constricting the blood vessels throughout the body.
- Carotid Artery: Sensors within the carotid arteries located within the neck can sense changes in blood pressure and send information to the brain to increase or decrease the blood pressure and work done by the heart.
Blood pressure readings consists of 2 numbers, the “systolic” on top and the “diastolic” on bottom.
Normal blood pressure is defined as a systolic pressure <120 mmHg and a diastolic pressure <80 mmHg. Therefore, 120/80 (or less) has been designated what is normal for good health.
What the Numbers Mean
- Systolic pressure is the force of blood from the heart to the body, a factor of the heart’s output with each contraction and the resistance down the line this force encounters
- Diastolic blood pressure is based on the baseline resistance of the tissues to which the blood is pumped
Types of Hypertension
Hypertension refers to an elevated systolic or diastolic pressure. An individual’s blood pressure is not static. It fluctuates constantly from the daily challenges of life–stress, danger, emotion, exertions, sex, fear of doctors, etc. Such temporary elevations are normal responses, so an isolated high number at any one point in time is meaningless unless it remains consistently high over time via multiple measurements.
In primary hypertension (“essential” hypertension), the cause is unidentifiable, however typically is a combination of genetics, age, environment, obesity, race, diet, and physical inactivity.
When there is a known or definitive cause or group of causes, hypertension is termed “secondary hypertension,” that is, it is secondary to another cause. Causes include:
- Medications: estrogen, NSAIDs, antidepressants, corticosteroids, stimulants, and other substances, including illicit abuse of methamphetamines and cocaine can raise blood pressure.
- Kidney disease: Including acute and chronic kidney disease, can alter the kidney’s ability to help manage blood pressure, one of its other main functions.
- Aldosteronism: Aldosterone, a hormone from the adrenal gland, directly affects the kidney’s function to eliminate salt (sodium), which impacts blood pressure. (This is why a low-salt diet is prescribed in hypertension.) When the aldosterone overacts to increase reabsorption of salt and water, the blood pressure will rise.
- Obstructive sleep apnea (OSA): OSA prevents the 10% “dip” in blood pressure we should all experience during sleep. Missing this nightly dip affects the average blood pressure over each 24 hours.
- Endocrine disorders: Diabetes, thyroid, and parathyroid disorders all have hormones that can exaggerate the effects that increase blood pressure.
Complications of Hypertension
High blood pressure damages the blood vessels within the body.. In arteries, injury from hypertension can result in the buildup of plaque (atherosclerosis) which can obstruct blood flow. The obstruction of blood flow can impair blood being delivered to key areas of the body such as the heart, brain, kidneys or other vital organs. Hypertension can also causes the heart to enlarge, injury to the kidneys resulting in increased risk for peripheral artery disease, heart attack or stroke.