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.