1, the heart is a magical pump The heart is a pump to maintain blood circulation, it pumps blood to the brain and all organs of the body, the heart stops working for a few minutes can lead to brain damage, and irrecoverable. The venous blood in the body carries metabolic waste and carbon dioxide from all parts of the body, through many, many veins, back to the right atrium, and then pumps blood through the right ventricle to the lungs, where it exhales carbon dioxide and combines oxygen into the blood; the oxygenated blood passes through the lungs again, back to the left atrium, and pumps blood through the left ventricle to the whole body. 2. The chambers and gates of the heart and the ductal system The heart has four chambers called the right atrium, the right ventricle, the left atrium and the left ventricle. The right and left atria or left and right ventricles cannot be directly connected and are separated by the interatrial septum and ventricular septum. If the atria are connected to each other or to the ventricles, it is called a congenital atrial septal defect or ventricular septal defect. Venous blood that flows back to the heart from the brain and upper extremities returns to the right atrium through a tube called the superior vena cava; venous blood that flows back to the heart from the lower part of the body returns to the right atrium through a tube called the inferior vena cava. There are three “doors” between the right atrium and the right ventricle, called the tricuspid valve. Blood is pumped through these “gates” into the pulmonary artery and then into the lungs; in the lungs, oxygen and fresh blood are sent to the left atrium through four tubes called pulmonary veins. The two “doors” between the left atrium and the left ventricle are called mitral valves. The three “doors” through which the blood exits the left ventricle are called the aortic valves. Blood is pumped to the periphery of the body through these “doors. If these doors are narrowed or do not close properly, you will have a heart condition called mitral, aortic, and tricuspid stenosis and/or insufficiency, respectively. The human heart is about the size of a fist, weighs about 1 pound, is located a little to the left of the back of the sternum, pumps 4.7 liters of blood per minute, and pumps 6,768 liters of blood per day. Many causes can cause the heart to increase in shape, weight and pumping volume, and produce various types of cardiomyopathy and cardiac insufficiency. 4. The heart’s command and liaison system – the electrophysiological system Every beat of the heart operates on the electrical signals of the heart (see the schematic diagram of the heart’s electrical conduction pathways). The highest command is something called the sinus node, which sends out instructions that control the rhythm and number of heart beats; this instruction, through a telephone wire-like conduction system, transmits electrical signals to various locations in the heart. When the signal is sent to the atria, it causes the atria to contract, so pumping blood into the diastolic ventricles; when the signal is sent to the ventricles, the ventricles contract, causing the right ventricle to pump blood to the lungs, while the left ventricle pumps blood throughout the body. The electrical signals from the atria are transmitted to the right and left ventricles through substation-like structures called atrioventricular nodes, and then through conduction wire-like structures called right and left bundle branches. All of this makes up the heart’s command and communication system. If there is a problem with the heart’s command and communication system for any reason, a heart rhythm disorder, also called arrhythmia, will occur. The heart itself is sensitive to the internal needs of the human body, and the heart beat will be adjusted automatically according to the needs of the human body; the heart beat will be accelerated when more oxygen and various nutrients are needed for exercise; the heart beat will be accelerated when there is fever or other diseases that require more oxygen and nutrients (such as cancer). At rest or during sleep, the heart beats slower. Under normal conditions, a healthy heart beats between 60 and 140 times per minute, and it adjusts the number of beats per minute according to the needs of the body. On average, it beats 120,000 times per day. When the body exercises and needs to pump more blood, the heart can increase the pumping volume by 4 times within seconds. 6, heart function indicators – ejection fraction The amount of blood ejected by the heart to the whole body during each contraction, divided by the amount of blood in the heart chambers during diastole, is called the ejection fraction. The ejection fraction of a normal healthy heart is 55% or more. Various heart diseases may lead to reduced ejection function, that is, reduced ejection fraction, and when it is reduced to 40% or less, the blood pumped out by the heart is not enough to provide the needs of various organs throughout the body. 7. Vessels that nourish the heart – coronary arteries The heart is an organ that delivers blood and nutrients throughout the body, but it also needs nutrition itself. It gets its nutrients through the coronary arteries. The coronary arteries are divided into the left and right coronary arteries. The section of the left coronary artery from the opening to the front of the bifurcation is called the left main trunk, and its condition often varies from person to person, some are longer, some are shorter; after the bifurcation of the left coronary artery, it is mainly divided into two branches, one is called the anterior descending branch and the other is called the left rotating branch, the right coronary artery is mainly one, and at the end it is divided into the posterior descending branch and the posterior lateral branch of the left ventricle. If diseased plaque forms within these coronary arteries and causes stenosis, the blood flow delivered to the heart will be reduced, resulting in symptoms ranging from mild chest pain to cardiac arrest, which can be life-threatening in severe cases. 8, the main component of the heart – cardiomyocytes The heart is mainly composed of cardiomyocytes, and each cardiomyocyte relies on a kind of interconnected called intercalary discs to work together to contract and diastolic, thus constituting the beating of the heart. After infancy and adolescence, adult cardiomyocytes have lost their ability to proliferate in their physiological state, meaning that the number of cardiomyocytes will not increase. Mature cardiomyocytes escape from the cell cycle and become terminally transformed cells. However, there are no stem cells in the myocardium that are capable of proliferating cardiomyocytes, so the cardiomyocytes eventually become terminated tissue and become stereotyped in adulthood and cannot regenerate and grow again. Once the myocardium is damaged, the myocardial cells will undergo vitreous degeneration and fibrosis and can only be repaired by scarring, and the necrotic myocardium is inevitably replaced by fibrous tissue after a myocardial infarction. Currently, our medical drugs, catheter interventions and surgical bypass surgery cannot repair and reverse the necrotic myocardium, which will eventually develop into congestive heart failure. This means that the contractility of the myocardium is weakened, thus reducing the ejection function of the heart. This inevitably leads to insufficient blood supply to the whole body. With the flourishing of “stem cell bioengineering”, it has been discovered that bone marrow contains stem cells with multi-differentiation potential and self-replication, providing an ideal cell source for cell transplantation to reconstruct necrotic myocardium. If bone marrow stem cells are used as a cell source to increase cardiomyocytes, they can be transplanted to increase cardiomyocytes and repair myocardial cells that have been reduced due to necrosis. Studies have been conducted to select bone marrow stem cells as donor cells and apply a less invasive clinical medical intervention method to reconstruct necrotic myocardium and improve cardiac function in patients with acute myocardial infarction via coronary artery transplantation. This new treatment method has achieved certain efficacy. 9, the heart is also an endocrine organ The heart and the pancreas, thyroid and other glands are also an endocrine organ, secreting many kinds of hormones. The renin-angiotensin-aldosterone system is also present in the heart, which also secretes a variety of peptides, the earliest of which is atrial natriuretic factor, atrial natriuretic peptide, also known as cardiac natriuretic hormone or atrial natriuretic hormone. It can interact with other hormones to precisely regulate blood pressure and volume. The brain natriuretic peptide it secretes is very useful in diagnosing the presence of heart failure. These hormones are important in the treatment of heart failure, among other things.