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Aside from the human brain the human heart has to be one of the most amazing powerhouses of the human body. From around twenty one days after conception the human heart begins beating and continues to beat until that human being’s dying day which is occasionally over one hundred years later! So what is it that makes this humongous machine so amazing? Why is it such a powerhouse? Let’s discover the human heart and find out!…
The Human Heart is the “Battery” of Living Beings
The human heart is composed of muscle, in fact the heart is found in all animals that posses a circulatory system due to the fact that the heart is the battery of that system. The human heart begins beating twenty one days after conception and beats on average seventy two times every minute, meaning that within a sixty six year lifespan the human heart will beat two and a half billion times! While this may seem amazing, even more amazing is the fact that the human embryonic heart rate peaks at one hundred and sixty five to one hundred and eighty five beats per minute! This rapid rate occurs around the seventh week of beating and then the embryonic heart rate tends to slow to an average rate of one hundred and fifty two beats per minute. The average normal human heart differs in weight between males and females with the male human heart weighing between three hundred to three hundred and fifty grams and the female heart weighing between two hundred and fifty to three hundred grams.
What is the Structure of the Human Heart?
The structure of the heart differs among species; however the human heart is a four chambered heart with two superior atria and two inferior ventricles. About the size of a fist the human heart is encased in a sac called the pericardium which protects the heart as well as serves to anchor the heart in position. The human heart is located behind the sternum and in front of the vertebral column. The pericardium also serves to prevent the heart from over filling with blood. The outer wall of the human heart has three layers: the epicardium, the myocardium and the endocardium. Each of these three layers is different from the previous layer. The epicardium is the very outer layer of the outer wall of the human heart and also serves as the inner wall of the pericardium. The myocardium is the middle layer of the outer wall of the human heart and is made from muscle, this muscle contracts as the heart beats. The endocardium is the inner layer of the outer wall of the human heart and covers the heart valves; it also combines with the inner lining of blood vessels as well as contacts the blood which the heart pumps.
Functioning of the Human Heart
The Human Heart has Four Chambers
Within the human heart are four chambers, two atria and two ventricles. The two atria receive the blood and the two ventricles send out the blood to the lungs in order that it may be oxygenated and send the blood to the rest of the body. It is the job of the right ventricle of the human heart to send blood to the lungs to be oxygenated and it is the job of the left ventricle of the human heart to send the blood to the rest of the body. Blood passes through the human heart in one direction and utilizes four valves which regulate the direction of blood flow. These four valves are the tricuspid valve, the mitral valve, the aortic valve and the pulmonary valve.
The Left and Right Sides of the Human Heart
The right side of the human heart is designated as the section of the heart which collects deoxygenated blood. This deoxygenated blood collects in the right atrium and travels through the tricuspid valve through the right ventricle where it travels to the lungs. In the lungs the blood picks up oxygen and releases carbon dioxide so that fully oxygenated blood can be passed through the body. This circuit within the body is called pulmonary circulation. The left side of the human heart is responsible for collecting the fully oxygenated blood from the lungs; this blood travels to the left atrium. This blood then moved through the left ventricle passing through the bicuspid valve which is responsible for delivering the oxygenated blood throughout the body through the aorta. This circuit within the body is called systemic circulation.
The lower ventricles of the human heart must be stronger than the atria due to the fact that the ventricles are utilized to push blood through the body rather than collect the blood. The left ventricle wall is also thicker than the right ventricle wall because of the fact that it takes more force to pass blood through the systemic system than it does to pass through the pulmonary system.
The Path Blood Takes Through the Human Heart
The actual path of blood through the human heart follows a distinct path beginning with the right atrium. From the right atrium the blood moves through the tricuspid valve in to the right ventricle. The tricuspid valve has three leaflets and three papillary muscles. Pathology in the tricuspid valve can result from illness or defect and causes blood to flow back in to the right atrium of the heart, referred to as regurgitation. Back flow of blood in to the heart is a common cause of endocarditis (infection of the heart tissue.) From the right ventricle, blood then moves through the pulmonary semilunar valve and travels to the lungs through the pulmonary artery. The pulmonary valve opens to allow the blood to pass through when the blood pressure in the right ventricle becomes higher than the blood pressure in the pulmonary artery. The blood pressure in the pulmonary artery is what causes the pulmonary valve to close following the movement of blood from the right ventricle in to the pulmonary artery. Through the pulmonary artery the blood moves to the lungs. In the lungs the blood is fully oxygenated in a process of diffusion where the carbon dioxide is exchanged for oxygen.
After oxygenation the blood travels through the pulmonary vein in to the left atrium of the heart. From the left atrium blood passes through the mitral valve in to the left ventricle. The mitral valve is also referred to as the bicuspid valve and serves to allow blood to flow from the left atrium to the left ventricle. The mitral valve serves as something of a one way doggy door which is triggered by the pressure of blood building up in the left atrium. Once the left atrium fills it pushes the flap (valve) and allows the blood to move through to the left ventricle. After the blood has moved through a normally functioning valve will close, preventing blood from flowing back in to the atrium. Certain diseases such as Mitral Valve Prolapse result in a thickening of the mitral valve and result in various problems such as mitral regurgitation, endocarditis, congestive heart failure and even cardiac arrest. Once the oxygenated blood has moved through a healthy mitral valve in to the left ventricle it is then sent through the aortic semilunar valve to the aorta. The aortic valve can become diseased as a result of illness and disease can result in two situations occurring. The first result of a diseased aortic valve can be aortic stenosis in which the aortic valve does not open sufficiently resulting in not all of the blood flowing out of the heart. The second result of a diseased aortic valve results in aortic regurgitation where blood flows back in to the heart against the one way flow system. Frequently individuals can experience both of these situations at once. Aortic valves have been known to be replaced through open heart surgery. Replacements involve an artificial heart valve or a heart valve created from animal tissue. Through the healthy aortic valve, however, the blood is sent to the aorta and is then sent out to major arteries through a fork to pump blood through the body and feed the cells throughout the body with oxygenated blood. After oxygen has been depleted from the blood it passes through venules which run in to veins and then in to the inferior and superior venae cavae which bring the deoxygenated blood back in to the right atrium where the blood begins its cycle all over again.
Tools Used by Cardiologists When Examining the Human Heart
Cardiac Ultrasounds are used to Pinpoint Heart Troubles
The functioning of the cardiac system is often observed through the use of cardiac ultrasound which allows cardiologists to view the heart in action. A cardiac ultrasound also referred to as an echocardiography or simply an “echo” utilizes sound waves to create an image of the functioning heart. While most cardiac ultrasounds utilize two dimensional images of the heart, more recent cardiac ultrasound equipment is able to put out three dimensional images of the heart as well. By utilizing cardiac ultrasounds cardiologists are able to see the heart functioning and pinpoint any obvious defects in the heart. The most common defects seen through cardiac ultrasounds are malfunctioning heart valves or abnormally sized heart structures. The cardiac ultrasound also enables cardiologists to assess the flow of blood through the heart to ensure that all is well. The cardiac ultrasound is the most commonly used tool by cardiologists to diagnose cardiovascular disease due to the fact that it can provide valuable information about the diseased heart quickly including: the hearts size, the hearts shape, the pumping capacity of the heart, any visible damage to heart tissue and the physiological state of all heart valves. The cardiac ultrasound not only gives a physical picture of the heart, but it also gives a snapshot of the heart in action, which allows cardiologists to see the blood moving through the heart and distinguish any abnormal blood flow patterns. Most cardiologists utilize the cardiac ultrasound because it is a noninvasive procedure that provides a wealth of information about the heart.
Electrocardiograms Are Used to Analyze Your Heart’s Rhythm
Another tool utilized by cardiologists to view information related to the hearts functioning is an electrocardiogram, also referred to as an ECG or EKG. An electrocardiogram is also a non-invasive procedure, however, it does not provide as much detailed information on the heart as the cardiac sonogram, it is also not able to detail information about any abnormalities in the physical structure of the heart. The electrocardiogram is employed by attaching small electrodes to the skin which record small electrical changes detected on the skin that occur each time the heart muscle reduces its electrical charge. The electrocardiogram notes these changes in electrical charge by recording on paper the rise and fall in electrical charge using a black line. The electrocardiogram is used to determine the rhythm of the heart and can point out weaknesses in various parts of the hearts muscle through the overall picture that develops on the electrocardiogram after testing. The electrocardiogram is best utilized when diagnosing abnormal heart rhythms as it provides a definitive picture of the hearts rhythm that changes depending on the arrhythmia of the heart.
Understanding the Human Heart Enables us to Live Longer
Throughout history human kind has learned a lot about the human heart and developed unique and ingenious ways to visualize this powerhouse without invasively observing it. These discoveries in terms of medicine provide humans with a much better chance at survival based on the fact that heart arrhythmias can quickly be detected and pinpointed without even opening the chest wall or guessing as to which area of the heart is malfunctioning by using a stethoscope. While the noninvasive discoveries made in terms of advancing cardiac care are certainly big steps there are also the invasive cardiological discoveries that have made such strides in terms of rehabilitating patients. Before open heart surgery, before valve replacements and bypasses an individual with “heart trouble” had no other option but to accept medication and the fact that their life was soon to be over. Now, with the discovery of so much more information about the human heart doctors are able to rebuild a weak heart and transplant newer valves in to replace the weaker and sickened valves. Such giant leaps forward in medical discovery have enabled so much more knowledge to be attained in relation to the human hearts function as well as enabled many thousands of people a second chance at life!
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