Anatomy
Summary
The heart is a muscular organ located between the lungs in the middle of the thorax responsible for pumping blood throughout the circulatory system. It consists of four chambers: the left and right atria and the left and right ventricles. The left atrium is the most posterior chamber of the heart and lies in front of the esophagus. Oxygenated blood flows from the left atrium into the left ventricle. The left ventricle is the left lateral portion of the heart and its thick walls ensure that blood is pumped to peripheral tissues.
The right atrium is the chamber where the superior and inferior vena cava return deoxygenated blood. The SA node is located near the opening of the superior vena cava in the right atrium. The AV node is located near the septal leaflet of the tricuspid valve. The right ventricle is the most anterior chamber of the heart. Pulmonary circulation begins from the right ventricle with blood entering the pulmonary trunk, which splits into the right and left pulmonary arteries carrying oxygen-depleted blood to the lungs. Oxygen-rich blood is returned to the left atrium via the four pulmonary veins, completing the pulmonary circuit. The pericardium is a double-walled sac that encloses the heart.
Lesson Outline
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FAQs
The heart is divided into four chambers: the left atrium, right atrium, left ventricle, and right ventricle. Anatomically, the atria are located at the upper part of the heart and receive blood, while the ventricles are the lower chambers that pump blood out of the heart.
Pulmonary circulation is a vital part of the circulatory system. Deoxygenated blood from the body enters the right atrium of the heart and is then pumped into the right ventricle. From there, blood is pumped to the lungs via the pulmonary arteries. Within the lungs, oxygen is added to, and carbon dioxide removed from the blood in a process known as gas exchange. The now-oxygenated blood returns to the heart, entering the left atrium before being pumped by the left ventricle into the systemic circulation.
The sinoatrial (SA) node is located in the right atrium near the opening of the superior vena cava. The atrioventricular (AV) node is located near the septal leaflet of the tricuspid valve and opening of the coronary sinus in the right atrium.
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