FREE ESSAY ON THE HEART AND ITS DISEASES

THE HEART AND ITS DISEASES

The Heart and Its Diseases
Cardiology has intrigued me since I was a small child. It has been my goal to become a
cardiologist ever since the first grade. Cardiology is more than just studying the heart.
To define it properly would be to say that cardiology is the study of the heart, its
action, and its diseases (Clayman 52). 
The heart is located in the center of the chest, just behind the sternum, sitting in a
hollow cavity between the lungs. The heart is slightly larger than your fist. It is about
five inches long, three inches wide, and two inches thick. The heart is commonly
represented in the familiar Valentine shape, but it actually resembles a grapefruit. The
external features of the heart consist of the pericardium. The function of the
pericardium is to support and protect the heart. The inside of the pericardium is lined
with a membrane that secrets a lubrication fluid which allows the pericardium to slide
smoothly over the surface as the heart pumps. 
The internal features of the heart are quite a bit more complicated than the external
features. The main features internally are the heart's four hollow spaces, which are
referred to as the chambers (Clayman 86). The pumping part of the heart consists of two
very thin walled upper chambers, which are given the name atria. The two thick-walled
lower chambers of the heart are called ventricles. The wall that divides the right side
of the heart from the left is called the septum. The muscles in these walls of the
chambers provide the pumping action of the heart. These muscles cause the chamber to
contract forcefully when the heart beats, which pushes blood through the body. The
chambers of the heart can be divided into three layers. The most important of the three
is the myocardium, which contains the muscles of the heart. The other two are called the
endocardium and the epicardium. The heart has a left and right side, which contains these
atriums and ventricles.
There are four valves, which aid in the function of keeping blood flowing in the right
direction (Katz 75). Two of these are known as the atrio-ventricular valves. These two
are named the mitral valve and the tricuspid valve. These valves allow the blood to flow
from each atrium into the corresponding ventricle. The mitral valve connects the left
atrium to the left ventricle, while the tricuspid connects the right atrium to the right
ventricle. The other two valves in the heart allow blood to flow to the body from the
ventricles but prevent blood from flowing backward into the ventricles from the body.
These valves are known as the semilunar valves. They are named this because they are
somewhat shaped like a crescent moon. The aortic semilunar valve allows blood to exit the
left ventricle and enter the aorta. The aorta carries blood to the body tissues. The
other valve is called the pulmonary similunar valve, which allows blood to exit the right
ventricle and enter the pulmonary arteries. These arteries carry blood to the lungs to
absorb oxygen, which is essential to our existence. These valves are designed to move
blood in one direction only, unless damaged by injury or disease.
The heart can be viewed as a precisely designed two-stage pump. The first stage is the
two atria, whose function is to ensure that the ventricles are fully inflated with blood.
When this occurs, the ventricles contract to force blood out into the body. Although both
sides of the heart contract at the same time, they have very different functions. The
right side of the heart receives oxygen free blood from the body and pumps it to the
lungs. The left side receives oxygen rich blood from the lungs and pumps it to the rest
of the body (Katz 95). Each red blood cell passes through the heart twice on its way to
tissues. The venae cavae aids in this process by returning the deoxygenated blood to the
heart. The venae cavae is also the largest vein in the body. The superior venae cavae
returns blood from the upper part of the body, while the inferior venae cavae returns
blood from the lower part. The oxygenated blood travels to the heart from the lungs
through four pulmonary veins. There are two for each lung. During this process, the blood
is distributed to the rest of the body. The body's largest artery, the aorta, is then put
to work, separating the blood to go to all branches of the body. 
The heart muscle is so active, that it uses about half its own weight in blood every
minute when the body is resting and up to twice its weight in blood during exercise.
Therefore, it is safe to say that the heart requires a lot of fuel to function. 
The heart also consists of two coronary arteries in which blood enters the heart's
network of blood vessels, and leaves by means of the cardiac veins. 
The heart pumps nearly 2000 gallons of blood each day and about 680,000 gallons each
year. The contracting and pumping phase of the heart is called the systole, and the
relaxing and filling phase is called the diastole. This is the way of measuring the blood
pressure. 
Now that it is clear how the heart functions, it is easier to understand the diseases. 
According to the American Medical Association, the incidence of heart disease over the
last twenty-five years has been reduced (Clayman 120). Despite this fact, about half of
all Americans will have a health problem regarding their heart or circulation. There are
many cardiovascular diseases. All of which are not to be taken lightly. The usual
symptoms of heart or circulatory disease is dizziness, fainting, breathlessness, chest
pain, palpitations, which is thumping in your chest or neck that makes you aware of your
own heartbeat, swollen ankles, and cramps in your chest region. If any of these signs
occur, a physical from your doctor is usually the first step that should be taken,
according to the American Medical Association. 
The first disease that is fairly common is the congenital heart disease. One person in
every 140 is born with a congenital heart defect (Clayman 88). This term congenital
means, "present from birth." This disease of the heart forms during the fetal stage. They
are considered to be anatomical abnormalities of the heart during the stage in which the
heart is developing. There are two divisions of this disease. There is the type in which
too much blood passes from the heart to the lungs, and not enough to the body. The other
is not enough blood passes to the lungs, causing the blood that is pumped to the body to
contain extremely low amounts of oxygen. The heart is formed in the early weeks of
pregnancy, which often women are not aware that they are pregnant. If a pregnant woman
contracts a viral infection at this time, it can lead to this disease in the unborn
child. Poorly controlled diabetes during pregnancy is another contributing factor to this
disease. There is also an increase of this disease in twins. In most cases, there is no
cause to be found though. So it is not necessarily the parent's fault. This disease is
not a hereditary disease. In fact, this disease is rarely found more than once in the
same family. If a newborn, or small child with symptoms of this disease is not treated
promptly, it will prove to be a fatal disease without question. Surgery could be an
option. This disease can be treated effectively, and monitored by a cardiologist. 
The next disease of the heart is called the coronary heart disease (Cheitlin 156). This
term is used to describe different disorders of the heart muscle that are caused by
restriction or blockage of its blood supply. This disease is the result of narrowing of
the coronary arteries. Angina is a pain, which is a symptom of this disease. The pain is
caused by exercise. It usually consists of a pressure discomfort behind the sternum.
Angina is brought on by the overexertion of the body. 
The most common of all coronary diseases is the term heart attack. This is potentially
very serious. It causes many deaths. It can easily be summarized by saying that a heart
attack is the formation of a blood clot on top of a plaque in an artery, causing the
blood supply to be cut off to a part of the heart. It occurs when this area is so
deprived of blood, it cannot function. This is called a myocardial infarction in medical
terms. Heart attacks tend to occur with little or no warning at all. In some cases,
patients who have had heart attacks have claimed to have a wave of fatigue rush over them
before the heart attack. The rate of survival of heart attack victims is climbing. In
1989, according to the American Medical Association, only 8 to 15 percent of heart attack
victims, who got to the hospital, died within three weeks. There is treatment for this.
An enzyme called streptokinase is put into the coronary by way of a catheter, and over 80
percent of cases with blocked arteries were opened again. 
Heart valve disorders are commonly diagnosed as the failure of the valves to open or
close properly. These disorders fall into two groups. The first disorder is when a valve
fails to open correctly. This obstructs the forward flow of the blood, and is called
stenosis. The second is when the valves fail to close properly. This causes a leakage of
blood. These valves are referred to as incompetent. The aortic and mitral valves are more
commonly affected by this valve disorder. Aortic stenosis is the most common heart valve
disorder in the United States. It affects men more often than women. Aortic insufficiency
is less common valve disorder. 
Heart muscle disease is when the pericardium is affected. This disease is referred to as
cardiomyopathy and myocarditis. In some cases the heart may be affected by a tumor. The
primary disorder affecting the pericardium is an inflammatory condition called
pericarditis. Viruses, bacteria, autoimmune disorders, and heart attacks can cause
pericarditis. In this case, a heart transplant might be the answer. 
Heart rate and rhythm disorders are another type of disease affecting the heart. A
healthy heart beats regularly at a rate of 60 to 100 beats per minute during rest. It is
normal for this rate to speed up during exercise or stress. Arrhythmias have two
classified groups. The first group is tachycardias, in which the heart rate is faster
than 100 beats per minute during rest. The bradycardias is when the heart rate falls
below 60 beats per minute during rest. Both are equally dangerous. The most common cause
of an arrhythmia is coronary heart disease. Treatment of an arrhythmia can consist of
prescription drugs, or insertion of a pacemaker. 
Heart failure seems like it would mean that the heart stopped beating. This idea is
wrong. Heart failure consists of the heart not keeping up with the task of pumping blood
to the lungs and body tissues. This condition is often serious. The person who has had
heart failure is in great danger of dying. Heart failure affects one in every one hundred
people. The causes of heart failure are coronary heart disease, and the continued strain
on the heart from high blood pressure. It can also occur when a normal heart is called
upon to beat fast or hard all of the time. This case sometimes occurs when someone has
the condition of thyroid overactivity. There are prescription drugs to help treat this,
and also diuretics are another option. In certain circumstances, mechanical aids are also
available. 
The heart is a necessity for existence. Without it functioning properly, the risks of
these diseases overcoming you are great. If you eat properly, exercise regularly, and
practice good health habits, the chances of you getting these diseases are dramatically
reduced. So, take care of your heart. You need it to survive. 
Bibliography
Cheitlin, Melvin D. MD. Dilemmas in Clinical Cardiology. Philadelphia: F.A. Davis
Company. 1990.
Cheitlin, Melvin D. MD; et al. McIlroy, Malcom B. MD. ; Sokolow, Maurice MD. Clinical
Cardiology. Sixth edition. Connecticut: Appleton & Lange. 1993.
Clayman, Charles B. MD. Your Heart. New York: The Reader's Digest Association, Inc.
1989.
DeBakey, Michael E. MD; et al. Gotto, Antonio MD. The Living Heart. New York 
David McKay Company, Inc. 1977.
Katz, Arnold M. Physiology of the Heart. New York: Raven Press. 1977.