What is Blood Pressure?
Blood pressure is the force created by the heart as it pushes blood into the
arteries and the circulatory system. When the heart pumps, it causes blood to
flow through the arteries and into the arterioles. As the blood goes through
the arterioles, the arterioles either contract or expand altering both the
amount of blood flow and the resistance to blood flow. If the arterioles remain
in a contracted form, they create high blood pressure. The heart must then
pump harder because the arterioles are exerting a greater resistance to blood
flow.
High blood pressure is often called the "silent killer". High blood pressure is
called this because there are usually no symptoms. Very high blood pressure can
also cause arteries to bulge (aneurysm) or burst (hemorrhage).
Blood Pressure and Heart Disease
High blood pressure is a risk for both heart disease and stroke.
Unfortunately, high blood pressure usually has no specific symptoms and no
early warning signs. It directly increases the risk of heart disease. High
blood pressure is a risk for heart disease because the heart is working harder
than normal thus putting the heart and the arteries under a greater strain.
When the heart is forced to work harder for long periods of time, the heart
becomes enlarged. A heart that is slightly enlarged may function okay but a
severely enlarged heart has a hard time pumping a sufficient amount of blood.
High blood pressure is also a risk for strokes.
It is estimated that over 60 million Americans have high blood pressure. Of
this 60 million, about 35 percent don't know they have it.
Blood pressure and Kidney disease
High blood pressure and kidney disease are closely related. High blood pressure
is a common cause of kidney failure in Australia . One mechanism for this is
the production of a hormone called 'renin' by the kidneys. If the kidneys
aren't functioning properly, renin can be produced inappropriately, raising the
blood pressure.
If high blood pressure is left unchecked, it can cause blood vessels in the
kidneys to become thickened and narrowed, possibly leading to reduced blood
supply and reduced kidney function.
Blood Pressure as a Tool
Blood pressure is an important diagnostic index, especially of circulatory
function. It is an important diagnostic index for many reasons. Firstly, any
condition that dilates or contracts the blood vessels or affects their
elasticity, affects the blood pressure. Secondly, any disease of the heart
that interferes with its pumping power, affects the blood pressure. In a
healthy animal, the blood pressure normal for its species is maintained within
a certain range with great constancy. Thus if blood pressure is abnormally low
or high, it usually indicates that greater health problems are present.
How is Blood pressure Measured?
Blood pressure is measured at two points, a high point and a low point. The
high point is the point at which the heart contracts to empty its blood into
the circulation, called systole. The low point is the point at which the heart
relaxes to fill with blood returned by the circulation, called diastole.
Pressure is measured in millimeters (mm) of mercury by an instrument called a
sphygmomanometer.
In humans, blood pressure doesn't vary greatly. In healthy persons, blood
pressure increases from about 80/45 in infants, to about 120/80 at age 30, to
about 140/85 at age 40 and over. Blood pressure increases with age because the
arteries loose elasticity.
Abnormally high blood pressure (hypertension) is considered a contributory
cause of arteriosclerosis. Abnormally low blood pressure (hypotension) is
observed in infectious and wasting diseases, hemorrhage, and persons who have
collapsed.
Causes of High Blood Pressure?
In about 10 percent of patients, the disease can be traced to specific causes:
heredity, kidney abnormalities, adrenal gland tumors, diabetes, chronic kidney
disease, hormone abnormalities, use of birth control pills, pregnancy or a
congenital narrowing of the aorta. This is called secondary hypertension. In
the other 90 percent of patients, the cause is unknown and is referred to
essential hypertension.
Does Blood Pressure stay the same?
No. Your blood pressure varies all the time to meet your body's needs. The
pressure will be different when you get up in the morning, to when you are
relaxing, exercising or sleeping. Blood pressure is usually at its highest when
we exercise, and lowest when we sleep. Blood pressure can also rise due to
anxiety, excitement, activity or nervousness. In general, blood pressure
remains fairly constant throughout the day.
How to Decrease Blood Pressure
There are many ways to decrease blood pressure. Blood pressure can be
decreased if a person exercises, doesn't smoke, limits salt intake, limits
alcohol intake and if obese, loses weight. Individuals who are very active
have a lower risk of getting high blood pressure (20 to 50 percent) than people
who are not active.
Medications for Blood pressure
Please note: Medications for blood pressure should be prescribed by and taken
under the direction of a doctor.
Diuretics: Commonly called "water pills," they lower blood pressure by reducing
the body's sodium and water volume
Vasodilators: These drugs relax the muscles in the blood vessel walls, causing
them to dilate, or widen
How is Blood pressure controlled?
Blood pressure is regulated largely by the nervous system. Hemoglobin, the
iron-protein compound that gives blood its red color, also plays a role in
regulating blood pressure. However, hemoblobin's affect is usually localized
and is not very useful when trying to control blood pressure on a large scale.
Hemoglobin contains nitric oxide, a gas that relaxes the blood vessel walls,
thus increasing blood flow. It controls the expansion and contraction of blood
vessels, and thus blood pressure, by regulating the amount of nitric oxide to
which the vessels are exposed.
Individuals with high blood pressure can be given medication to lower their
blood pressure. Mild cases of blood pressure can be treated through behavior
modification like changing diet and increasing exercise. More severe cases of
hypertension require medications like diuretics and beta blockers. Diuretics
rid the body of excess fluids and salt. Beta blockers reduce the heart rate and
the heart's output of blood.
Blood Pressure Statistics
As many as 50 million Americans aged 6 and older have high blood pressure.
One in five Americans (and one in four adults) has high blood pressure.
Of those people with high blood pressure, 31.6 percent don't know they have it.
People with lower educational and income levels also tend to have higher levels
of blood pressure.
Non-Hispanic blacks and Mexican Americans are more likely to suffer from high
blood pressure than are non-Hispanic whites.
Who is at risk for High Blood Pressure?
In the early and middle adult years, men have high blood pressure more often
than women. But as men and women age, the reverse is true. Unfortunately, more
than half of all Americans over age 65 have high blood pressure.
