A
healthy heart pumps blood to your tissues to provide cells with
the oxygen and nutrients they need. Blood travels through your
circulatory system consisting of arteries taking blood to the
tissues and veins bringing it back to the heart. The blood is
then cycled through the lungs to get re-oxygenated before the
cycle starts again.
The
heart has two pumps, each consisting of a pair of chambers formed
of muscles. When these muscles contract, they pump blood. The
lower chamber of each part is called a ventricle while the upper
chamber is called an atrium. All four chambers are connected by
valves. Heart tissue has three layers. The exterior layer is the
thin epicardium. In the middle is the myocardium which is the
heart muscle. Inside, the endocardium lines the heart. The heart
is enclosed inside the pericardium, a fibrous sac with a smooth
lining, with a small amount of fluid between the epicardium and
the pericardium.
Blood
returning to the heart from the tissues enters the right atrium.
This atrium moves the blood through the tricuspid valve into the
right ventricle.
The
right ventricle's thicker, stronger walls pump the oxygen-poor
blood through the pulmonic valve into the lungs. The blood travels
through a series of smaller vessels to the capillaries, where
the blood cells absorb oxygen and release carbon dioxide.
The
heart's pumping action moves the blood back to the heart to the
left atrium, which gently pumps the oxygen-rich blood through
the mitral valve into the left ventricle. The left ventricle's
powerful pumping sends the blood into the aorta, the main artery
that divides into smaller vessels to deliver blood to the body
including the brain, organs, arms, and legs.
Contraction
of the ventricles to force blood out is called systole, while
the relaxation of the ventricles to allow blood in is diastole.
The right and left sides contract and relax at the same time.
The
rate at which your heart pumps depends on your activities at the
moment. When you are resting or sitting quietly, your heart pumps
more slowly. When you run or climb stairs, for example, it pumps
faster to provide your muscles and tissues the oxygen they need.
The
heart's relationship to the lungs --- what a team!
Your
heart and lungs need each other to supply your body with oxygen-rich
blood and to get rid of carbon dioxide. Your lungs inhale air
which travels through the airways down to tiny air sacs called
alveoli, which are lined with tiny blood vessels called capillaries.
At this point, oxygen is absorbed by your blood and carbon dioxide
is released into the air. This is called gas exchange, and is
your body's most basic, essential function.
Your
heart's pumping gathers this oxygen-rich blood and distributes
through a system of arteries to your brain, organs, muscles and
tissues. A system of veins collects the blood, which travels back
to the heart to be pumped to the lungs to start over again.
Risk
factors for heart disease that you can control
High
blood pressure (hypertension) can damage the arteries throughout
the body so that the artery walls become thick and stiff. This
condition is called arteriosclerosis. In persons with high concentrations
of fat in their blood, fatty deposits will further narrow the
arteries. As a result, blood flow is decreased to vital organs
such as the brain, heart and kidneys. The body responds by increasing
blood pressure to maintain an adequate flow of blood, setting
in motion a vicious cycle which takes its toll on the heart.
A
typical blood pressure reading is 120/80 millimeters mercury (mm
Hg). This means the heart is creating a maximum pressure of 120
mm Hg when it pumps, and a pressure of 80 mm Hg when it rests
between beats.
High
blood pressure has no apparent symptoms, and is usually detected
during a doctor's examination. Treatments vary, but include drugs,
quitting smoking, and other lifestyle changes. To avoid high blood
pressure, limit your use of salt and avoid weight gain by regular
physical activity. Have your blood pressure measured at least
once a year.
Smoking
not only causes lung cancer, but also doubles the risk of sudden
cardiac death. It causes your adrenal glands to secrete a hormone
that temporarily increases your blood pressure and makes your
heart work harder. It also decreases the amount of oxygen going
to your heart. Smokers also have more atherosclerosis than nonsmokers
do, probably because smoke increases the clumping of blood platelets
which is a stimulus for cholesterol to deposit in the arteries.
Cholesterol
and dietary fats in your blood has a strong influence on future
developments of atherosclerosis and its complications including
coronary artery disease and stroke. Take the precautions of having
your blood cholesterol measured regularly, following a preventive
diet, controlling your weight, and avoiding tobacco. A cholesterol
test will measure three blood fats: total cholesterol, high density
lipoprotein (HDL) cholesterol, and triglycerides. A fourth value,
low density lipoprotein (LDL), is derived from a calculation based
on the other three measurements. HDL cholesterol (the good cholesterol)
is the clean-up cholesterol that decreases the undesired cholesterol,
LDL.
Normal
total cholesterol is defined as less than 200 mg/100 mL, and if
you are in this range you should be tested every four to five
years. Borderline cholesterol is in the range of 200 to 239 mg/100
mL. If you are in this range, dietary changes and exercise are
recommended. Abnormal total cholesterol is 240 mg/100mL or above.
Some doctors advise drug therapy if this level remains despite
dietary changes.
Obesity
is defined as exceeding your ideal weight by 20 percent or more.
Obesity is a risk factor for heart disease when it is associated
with other risk factors such as high blood pressure and high blood
cholesterol. A sensible program of dietary adjustment and exercise
can help you reduce your risk.
Diabetes
is a condition caused by lack of insulin resulting in the body's
inability to process sugar. Insulin and other drugs have made
diabetes a manageable disease, but it remains a risk factor for
heart disease. Increased blood sugar level is often accompanied
by increased fat level, which can lead to atherosclerosis and
other blood vessel problems.
If
you are a diabetic, carefully manage your blood sugar level. Dietary
measures, weight control, exercise, and insulin or other anti-diabetic
drugs can help.
Sedentary
lifestyles lead to deconditioned hearts. Like any muscle,
the heart needs exercise to maintain its endurance and ability
to pump blood. Exercise can help decrease your normal heart rate,
lower blood pressure, decrease fat levels in your blood, and help
control weight. The best exercise is aerobic activity that involves
continuous movement such as running or swimming.
Heart
related links
American
Heart Association
Information and programs on heart health, disorders and research
American
Medical Association
Information about a wide range of medical issues
