When you have your
blood pressure taken, your health care provider is measuring the
pressure, or tension, that
blood exerts on the walls of the
blood vessels as it travels around the
body. In a healthy
person, this
pressure is just enough for the
blood to reach all the cells of the
body, but not so much that it strains
blood vessel walls.
Blood
pressure is measured in millimeters of mercury (mm Hg).
· A typical normal
blood pressure is 120/80 mm Hg, or “120 over 80.”
· The first number represents the
pressure when the
heart contracts.
· The second number represents the
pressure when the
heart relaxes.
· Blood
pressure greater than 140/90 mm Hg is considered high.
Generally,
blood pressure will go up at certain times – for instance, if you smoke a cigarette, win the lottery, or witness a car crash – and will return to normal when the stressful or exciting event has passed.
But when
blood pressure is high all the
time, the continuous increased force on
blood vessel walls can damage
blood vessels and organs, including the
heart, kidneys, eyes, and brain.
The medical term for high
blood pressure is hyper tension.
Need to Know:
Systolic and Diastolic Blood Pressure
Blood travels through
blood vessels much like
water through a garden hose. The
blood in the vessels is under
pressure just like the
water in a hose when the tap is turned on.
With each heartbeat more
blood is pumped into the vessels – like turning up the tap – so the
pressure rises. This is the systolic
blood pressure, the first number in the
blood pressure measurement, which is normally around 120.
Between heartbeats, while the
heart is resting, the
pressure in the arteries is lower. This is the diastolic
pressure, second number in the
blood pressure measurement, which is normally around 80.
Indication of high
blood pressure
You can increase the
pressure in a hose either by turning up the tap or by putting a crimp in the hose (that is, by narrowing the hose). In this same way, the
blood pressure in
blood vessels will rise if fluid flows more forcefully or if the arteries are narrowed.
Pressure in a hose can be regulated either by controlling the rate at which fluid passes through it or by widening it. Likewise, the
pressure in the
blood vessels can be controlled, with medications that act on the
heart or
blood vessels and with certain lifestyle modifications.
Need to Know:
Although high
blood pressure can be extremely dangerous, it usually causes no symptoms – so many people don’t even realize they have it. High
blood pressure can only be detected with accurate and repeated measurements of a
person‘s
blood pressure. That’s
one reason why it’s so important to have regular medical checkups.
Even though high
blood pressure can be treated safely and effectively, only about
one-quarter of people who have high
blood pressure take the necessary steps to keep their
blood pressure within a normal range.
There are three types of hypertension:
Primary hypertension (essential hypertension). This is high
blood pressure for which no cause can be found. Most people with high
blood pressure (90 to 95
percent) have this type of hypertension. Doctors suspect that a combination of lifestyle, diet, heredity, age, gender, race/ethnicity, hormone levels, and other factors all contribute to high
blood pressure.
Secondary hypertension (non-essential hypertension). This is high
blood pressure for which a definite cause can be found. This type of high
blood pressure accounts for only 5 to 10
percent of all cases of hypertension. Some of these causes are temporary or controllable – for instance, pregnancy or the use of certain medications – while others are chronic conditions like hormonal diseases, kidney disease, or head injuries.
Isolated systolic hypertension (ISH). Older people are sometimes susceptible to another form of high
blood pressure, called isolated systolic hypertension. In people with this condition,
blood pressure is higher than normal when the
heart beats, but returns to normal in between beats of the
heart. The large difference in
pressure can place additional strain on artery walls.
Nice To Know:
Q. If I do not feel any symptoms, is there still a problem?
A. Most people with high
blood pressure do not experience any symptoms. The presence of symptoms, such as headache or blurry vision, usually indicates severe or long-standing hypertension. However, over
time, uncontrolled high
blood pressure causes significant damage to important organs including the
heart, kidneys, brain, and eyes. In a number of cases, this damage can lead to death. This is why high
blood pressure is sometimes referred to as “the silent killer.”
Facts about high
blood pressure
High
blood pressure is a condition in which the
pressure, or tension, that
blood exerts on the walls of
blood vessels goes up and stays high, which can damage the
blood vessels, the
heart, and other organs.
It is estimated that more than 50 million Americans have high
blood pressure.
High
blood pressure is
one of the most serious health problems in the
United States; yet, because high
blood pressure has no symptoms, millions of people do not even know they have it.
As many as
one in four adults in the
United States has high
blood pressure.
High
blood pressure affects people of all ages, racial and ethnic groups, and walks of
life.
Doctors do not know what causes high
blood pressure in 90 to 95
percent of people who have it.
High
blood pressure is
one of the most important risk factors for coronary
heart disease.
High
blood pressure is the most important risk factor for stroke, which is the third leading cause of death in the
United States.
High
blood pressure is a
common cause of
heart failure, the leading cause of death in the
United States
High
blood pressure is a
common cause of kidney disease.
What Factors Affect Blood Pressure?
Blood pumped through
blood vessels is always under
pressure, much like
water that is pumped through a garden hose. This
pressure is highest in the arteries closest to the
heart and gradually decreases as the
blood travels around the
body.
Blood keeps moving around the
body because there are differences in
pressure in the
blood vessels. Blood flows from higher-
pressure areas to lower-
pressure areas until it eventually returns to the
heart.
Hypertension is much strain on your
heart
Blood
pressure is controlled by three things:
1 – How fast the
heart beats (
heart rate). The pace at which the
heart beats, or
heart rate, is counted in heartbeats per
minute. Generally, when
heart rate increases,
blood pressure rises. When
heart rate decreases,
blood pressure drops.
2 – A number of things affect
heart rate, including the
body‘s nervous system; chemical messengers called hormones,
body temperature, medications, and diseases.
3 – How much
blood the
heart pumps with each beat (stroke volume). The amount of
blood pumped out of a ventricle with each heartbeat is called stroke volume. When you’re resting, stroke volume is about the same as the amount of
blood that veins carry back to the
heart. But under stressful conditions, the nervous system can increase stroke volume by making the
heart pump harder.
Stroke volume can also be affected by certain hormones, drugs, and diseases, as well as increases or decreases in the amount of
blood in the
body, called
blood volume.
Nice To Know:
You might also hear the term “cardiac output” used to describe the amount of
blood that’s pumped through the
body. Cardiac output is simply the amount of
blood pumped out of a ventricle in
one minute:
Cardiac output = Heart rate x Stroke volume (amount of
blood pumped with each beat)
As cardiac output increases, so does
blood pressure. This is why
heart rate and stroke volume are important ways for the
body to control
blood pressure.
How difficult it is for
blood to travel around the
body (peripheral resistance). The third major component that affects the
blood pressure is the caliber or width of the arteries. Blood traveling in narrower vessels encounters more resistance than
blood traveling through a wider vessel (its harder for
water to pass through a narrow pipe than a wide pipe).
Depending on what a
person is doing, the amount of
blood the
heart pumps varies enormously. Yet the
blood pressure normally remains pretty stable. That’s mainly because the
body adjusts the resistance of the arteries, either widening or narrowing the
m as appropriate, to prevent the
blood pressure from swinging wildly.
This ability to regulate the width of the
blood vessels is called the peripheral resistance. Most of the resistance to
blood flow in the circulation occurs in the small-diameter arteries called arterioles.
These arterioles are especially important in the immediate regulation of
blood pressure. That’s because they contain specialized smooth muscle in their walls that can relax or contract, allowing the
blood vessel to get wider or narrower.
