Human heart anatomy | human heart chambers
The human heart
The human heart is a four-chambered muscular organ that is responsible for pumping blood throughout the body. The heart is located in the mediastinum, the central compartment of the thorax. The heart is enclosed in a double-layered sac called the pericardium. The heart has four valves that prevent the backflow of blood.
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Location of the heart
The human heart is situated in the middle mediastinum, at the level of thoracic vertebrae T5-T8. A double-membraned sac called the pericardium surrounds the heart and attaches to the diaphragm. The heart rests on the diaphragm with the larger, flattened bottom notched area of the heart, called the base, directed downwards.
Structure of the heart
The heart is a hollow, cone-shaped muscle that lies slightly to the left of the center of the chest. It weighs about 10.5 ounces (300 grams) and measures about 5 inches (12.7 centimeters) in length. The heart is divided into four chambers: the right and left atria above, and the right and left ventricles below. A double-layered membrane called the pericardium encloses and protects the heart.
The four chambers of the heart
The human heart is a four-chambered muscle that pumps blood throughout the body. The four chambers are the left and right atria, and the left and right ventricles. The atria are the upper chambers of the heart, and the ventricles are the lower chambers. The left atrium and left ventricle are on the left side of the heart, and the right atrium and right ventricle are on the right side.
The right atrium
The right atrium is one of the four chambers of the heart. It receives deoxygenated blood from the body and pumps it to the right ventricle. The right atrium is separated from the left atrium by the interatrial septum. The right atrium is a thin-walled muscular chamber that collects deoxygenated blood from the body's veins. It is located on the right side of the heart and pumps blood into the right ventricle.
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The right ventricle
The right ventricle is one of four chambers in the human heart. It is located on the right side of the heart and receives deoxygenated blood from the right atrium. The right ventricle pumps the blood into the pulmonary artery, which takes it to the lungs for oxygenation. The walls of the right ventricle are thin, compared to those of the left ventricle, because it doesn't have to pump the blood as far or as forcefully.
The left atrium
The left atrium is one of the four chambers of the heart, located on the left upper side of the heart. The left atrium receives oxygen-rich blood from the lungs and pumps it into the left ventricle. The left atrium is a thin-walled chamber that enlarges when it fills with blood. The walls of the left atrium are composed of three layers: an inner layer of endothelium, a middle layer of smooth muscle, and an outer layer of fibrous tissue. The smooth muscle layer contracts to push blood into the ventricle, and the fibrous tissue helps support the heart and keep it in place. The left atrium is smaller than the right atrium, but its walls are thicker because they have to pump blood against a higher pressure in the ventricle. The inner surface of the left atrium is lined with microscopic projections called cilia that help move blood into the ventricle. There are also several openings in the atrium that allow blood to flow into different parts of the heart.
The left ventricle
The left ventricle is one of four chambers in the human heart. The others are the right ventricle, the left atrium, and the right atrium. The left ventricle is the largest and strongest chamber. Its job is to pump oxygen-rich blood to all parts of the body. The left ventricle is about the size of a fist. It is cone-shaped, with a small opening at the top and a large opening at the bottom. The bottom opening is called the aortic valve. The aortic valve opens and closes with each heartbeat. It keeps blood from flowing back into the left ventricle when it contracts. The walls of the left ventricle are much thicker than those of the right ventricle. This is because they have to pump blood all over the body, against gravity. The thicker walls also help keep blood from leaking backward through the aortic valve when the ventricle relaxes between beats.
The four valves of the heart
The four valves of the heart are the aortic valve, pulmonary valve, tricuspid valve, and mitral valve. These valves are open and closed to control the flow of blood through the heart. The aortic valve opens to allow blood to flow from the left ventricle into the aorta. The pulmonary valve opens to allow blood to flow from the right ventricle into the pulmonary artery. The tricuspid valve opens to allow blood to flow from the right atrium into the right ventricle. The mitral valve opens to allow blood to flow from the left atrium into the left ventricle.
The tricuspid valve
The tricuspid valve is one of the four valves of the heart and is responsible for regulating blood flow between the right atrium and right ventricle. It is composed of three leaflets (tricuspid means three-lobed), and it is located on the right side of the heart. The tricuspid valve opens when blood flows from the right atrium into the right ventricle, and it closes when blood flows from the right ventricle into the pulmonary trunk.
The pulmonary valve
The pulmonary valve is a valve in the heart that separates the right ventricle from the pulmonary artery. It prevents the backflow of blood from the pulmonary artery into the right ventricle during ventricular diastole. The valve has three cusps or leaflets: the anterior, posterior, and septal cusps.
The mitral valve
The mitral valve is a heart valve that sits between the left atrium and the left ventricle. It is also known as the bicuspid valve because it has two cusps or flaps. The mitral valve opens to allow blood to flow from the left atrium into the left ventricle, and then closes to prevent blood from flowing back into the left atrium.
The aortic valve
The aortic valve is located between the left ventricle and the aorta. The aorta is the large artery that carries blood from the heart to the rest of the body. The aortic valve has three cusps or leaflets that open and close with each heartbeat. Blood flows through the cusps from the ventricle into the aorta. When the heart relaxes, blood flows back into the ventricle through the aortic valve. If one or more of the cusps are not shaped correctly, it can cause problems with blood flow.
The coronary arteries
The coronary arteries are the arteries that supply oxygenated blood to the heart muscle. They arise from the left main coronary artery, which branches off from the aorta. The coronary arteries supply nutrients and oxygen to the heart muscle (myocardium) and help to remove waste products.
The right coronary artery
The right coronary artery (RCA) is one of the two major arteries that supply oxygenated blood to the heart muscle. The other is the left main coronary artery (LMCA). The RCA branches off from the LMCA and travels down the right side of the heart. It supplies blood to the right atrium, right ventricle, and a small portion of the left ventricle. A blockage or an obstruction in the RCA can lead to a heart attack.
The left anterior descending artery
The left anterior descending artery (LAD) is one of the two arteries that supply the anterior (front) portion of the left ventricle of the heart. The LAD is also known as "the widow-maker" because a blockage in this artery is often fatal.
The left circumflex artery
The left circumflex artery (LCX) is a branch of the left main coronary artery. It runs in a clockwise direction around the heart, posterior to the left atrium and anterior to the left ventricle. The LCX gives off branches that supply blood to both the left atrium and ventricle. It also supplies blood to parts of the heart muscle itself.
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