Human Heart
The Human Heart is a fist-sized muscular organ functioning as the body’s circulatory system. It receives deoxygenated blood through the veins and transports it to the lungs to be oxygenated, which is pumped into the arteries. The arteries supply the body’s tissues with oxygen and nutrients, transporting blood throughout the body.
Location of heart, Size of heart
The human heart is located in the thoracic cavity, median to the lungs and just behind and slightly left of the breastbone.
The human heart is located precisely on the left side of the chest. It is about the Size of a fist. It is located between the left and right lungs. located behind the sternum and is slightly tilted to the left.
If you hold your right hand in the centre of your chest and move it slightly to the left, you can reach the heart’s exact location. The spine is behind the heart, and the lungs are on either side.
Anatomy of the Heart (Heart Structure)
Our heart comprises several layers of tough muscular wall called the myocardium. A thin layer of tissue (the pericardium) lines the outside. Another layer, called the endocardium, lines the inside. The cavity of the heart is divided into four chambers. The upper chamber is called the atrium, and the lower chamber is called the ventricle. The two atria serve as chambers for receiving blood, and the two ventricles push it out.
Chambers of the heart
The heart has four chambers, as debated herein.
- Right atrium: Receives plasma from the veins and pumps it into the right ventricle.
- Right ventricle: Receives blood from the correct atrium and pumps it into the lungs.
- Left atrium: Receives oxygenated blood from the lungs and pumps it into the left ventricle.
- Left ventricle: This is the most powerful chamber of the heart. It pumps oxygenated blood throughout the body.
The atria are smaller than the ventricles. They are also thinner and have less muscular walls than the ventricles.
The atria function as blood-receiving chambers connected to the veins that transmit blood to the heart. The ventricles are larger, thicker, and stronger because they must pump blood from the heart to the entire body. The ventricles are coupled to the arteries that carry blood from the heart to the rest of the body.
Pericardium
The heart is located in a fluid-filled cavity called the pericardium. The walls and lining of the pericardium are formed by a special membrane called the pericardium.
The pericardium produces serous fluid, which lubricates the heart and prevents friction between the constantly working heart and the surrounding organs. Pericardium also holds the heart in the right position and maintains the cavity, allowing it to expand when filled. The pericardium consists of two coatings: the visceral layer, which covers the outer area of the heart, and the parietal layer, which forms a sac around the pericardial cavity.
Heart wall
Epicardium: The epicardium is the surface layer of the heart wall. It is also called the visceral pericardium. It is a thin layer of serous membrane that lubricates and protects the heart.
Myocardium: The myocardium is the middle brawny layer of the heart wall that covers cardiac muscle tissue. The myocardium makes up most of the thickness and mass of the heart wall. It is responsible for pumping blood.
Endocardium: The endocardium is a single-layer flat endothelium that lines the inside of the heart. The endocardium prevents blood from sticking to the inside of the heart and causing life-threatening blood clots.
Thickness of the heart wall
The thickness of the heart wall varies depending on its section. For example, the atria have a very thin myocardium because they do not need to heart blood over long distances. They only need to pump it to the neighbouring ventricles. On the other pointer, the ventricles are responsible for pumping blood to the break of the body’s tissues. Therefore, the ventricles have a thick myocardium to pump blood to the lungs or through the body.
The right side of your heart has fewer myocardium in its ramparts than the left side because the left side has to pump blood finished the entire body, while the correct side only has to pump blood to the lungs.
Valves of the Heart
The heart pumps plasma to the lungs and tissues of the body. It is equipped with a system of one-way valves that prevent backflowing of blood.
There are two types of heart valves:
- Atrioventricular valves: The auriculoventricular (AV) valves are located in the heart’s centre, between the atria and ventricles. They allow blood to flow from the atria to the ventricles.
- Semilunar valves: The valves are located amongst the ventricles and the highways that carry blood away after the heart. The crescent valve on the correct side of the heart is called the pulmonary valve because it prevents blood from flowing back from the pulmonary artery into the right ventricle. The semilunar valves get their name from the sickle-shaped shape of the valves.
Function of the Heart
The right atrium obtains blood from the head, chest, and arms via the larger vena cava and the abdomen, pelvic area, and legs via the inferior vena cava. The blood passes finished the tricuspid valve into the right ventricle. The blood is then transported through the pulmonary artery to the lungs.
In the lungs, venous blood comes into contact with air, mixes with oxygen, and releases carbon dioxide. The oxygenated blood returns to the left entrance via the pulmonary veins. As mentioned above, the heart’s valve system allows blood to flow in only one direction and prevents backflow. This helps maintain the pressure needed to pump blood.
The Cardiac Cycle
The cardiac cycle includes events that take home during one heartbeat. There are three stages in a cardiac cycle:
- atrial systole
- ventricular systole
- relaxation
Atrial systole: During the atrial systole stage of the cardiac cycle, the atria contracts and pushes blood into the ventricles. The atrioventricular (AV) valves remain open and the semilunar valves remain closed, preventing backflow of arterial blood into the heart. The atria are much smaller than the ventricles, filling only about 25% of the ventricles during this phase. During this phase, the ventricles are in diastole.
Ventricular systole: During this cardiac cycle phase, the ventricles contract, assertive blood into the aorta and pulmonary artery. The pressure in the ventricles causes the semilunar valves to open and the atrioventricular valves to close. This allows blood to flow from the ventricles into the arteries. During this phase, the cardiac muscles of the atria repolarise and enter diastole.
Relaxation phase: During this phase, all four heart chambers are in diastole as blood flows into the heart from the veins. During this phase, the ventricles fill to about three-quarters of their capacity. The cardiac muscle cells of the ventricles repolarise during this phase, preparing for the next round of depolarisation and contraction. The atrioventricular valves open, allowing blood into the ventricles, while the semilunar valves remain closed.
Blood Flow through the Heart: Healthy heart blood flow patterns
Deoxygenated blood from the body enters the heart finished the superior and inferior vena cava. It then enters the right atrium and is pumped into the right ventricle. The blood is drove through the pulmonary semilunar valve into the pulmonary trunk.
The pulmonary trunk transports blood to the lungs. Here, carbon dioxide is free and oxygen is absorbed. The blood returns to the heart finished the pulmonary veins.
The left atrium contracts, pumping blood through the mitral valve into the left-hand ventricle. The left ventricle pumps blood finished the aortic crescent valve into the aorta. The blood enters the systemic circulation through all the tissues of the body. It then returns to the heart through the semilunar vein, and the cycle repeats similarly.
Common diseases and conditions of the heart
Coronary artery disease (CAD):
Cholesterol plaques narrow the arteries that supply blood to the heart. The narrowed arteries in coronary thrombosis artery disease are at increased risk of becoming blocked by a sudden blood clot. This blockage is called a myocardial infarction.
Angina:
Narrowing the coronary arteries causes sharp chest pain or discomfort during physical activity. This is called angina. Symptoms usually improve with rest.
Myocardial infarction (heart attack):
A heart attack ensues when a coronary artery is suddenly blocked. Part of the heart power dies due to a lack of oxygen.
Arrhythmia:
Arrhythmia is an abnormal heart rhythm caused by changes in how electrical impulses travel through the heart. It can be life-threatening.
Congestive heart failure (or just heart failure):
Doctors call it heart failure when the heart is too weak or too stiff to heart blood around the body effectively. Common symptoms include shortness of breath and swelling in the legs.
Cardiomyopathy (enlarged heart):
Cardiomyopathy is when the heart becomes abnormally large. The heart’s ability to heart blood is reduced. It can be life-threatening.
Myocarditis:
Myocarditis is an crossness of the heart muscle, usually caused by a viral infection. However, there can be other causes of inflammation.
Pericarditis:
Pericarditis is an inflammation of the heart’s lining (pericardium). Viral infections, kidney failure, and autoimmune diseases can cause it.
Signature Arrhythmia:
Atrial fibrillation is a type of arrhythmia. It is characterised by abnormal electrical impulses in the atria, which cause the heart to beat irregularly.
Heart Murmur:
A heart murmur is an abnormal complete that can be heard with a stethoscope. Some heart murmurs are benign, while others indicate heart disease.
Endocarditis:
Endocarditis is an redness of the heart’s inner lining or the heart valves. An infection of the heart valves usually causes endocarditis.
Mitral Valve Prolapse:
In mitral valve prolapse, the valve shifts slightly backwards after blood passes through it.
Cardiac Arrest:
Cardiac arrest is the hasty loss of heart function.
Sudden Cardiac Death:
Death caused by the sudden loss of heart function (cardiac arrest) is called sudden cardiac death.
Hypertension:
Hypertension is also recognized as high blood pressure. In hypertension, blood pressure is usually higher than usual.
Venous Thromboembolism (VTE):
Venous thromboembolism is a disorder that combines two other conditions: deep vein thrombosis (DVT) and pulmonic embolism (PE).
Peripheral Arterial Disease:
Peripheral arterial illness is a circulatory disorder in which the peripheral arteries become narrowed and stop supplying oxygen.
Ventricular septal defect (VSD):
A ventricular septal defect is a congenital heart defect in which a hole forms in the divider (septum) of the heart.
Hypotension:
Hypotension is a disorder in which the weight of the blood flowing in the arteries is lower than usual.
Pulmonary embolism:
In a pulmonary embolism, a blood clot travels complete the heart to the lungs.
Heart valve disease:
The heart has four valves, and any one of them can cause problems. In severe cases, valve disease can lead to congestive heart failure.
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