Atrium

Atrium

The atrium is a vital anatomical structure in the human heart, playing a crucial role in the circulatory system. The heart consists of four chambers: two atria and two ventricles. The atria are the upper chambers of the heart, with the right atrium and left atrium each serving distinct functions in the cardiac cycle.

Anatomy

Right Atrium

The right atrium is located on the right side of the heart. It receives deoxygenated blood from the body through the superior vena cava and inferior vena cava. The right atrium also receives blood from the coronary sinus, which drains blood from the heart muscle itself. The blood then flows from the right atrium into the right ventricle through the tricuspid valve.

Left Atrium

The left atrium is situated on the left side of the heart. It receives oxygenated blood from the lungs via the pulmonary veins. The blood then passes from the left atrium into the left ventricle through the mitral valve.

Function

The primary function of the atria is to act as receiving chambers for blood returning to the heart. They play a critical role in maintaining efficient blood flow and ensuring that the ventricles are filled adequately before contraction. The atria contract slightly before the ventricles, a process known as atrial systole, which helps to "top off" the ventricles with blood.

Clinical Significance

Atrial Fibrillation

Atrial fibrillation is a common cardiac arrhythmia characterized by rapid and irregular beating of the atria. This condition can lead to blood clots, stroke, heart failure, and other heart-related complications. Management of atrial fibrillation may include medications, lifestyle changes, and procedures such as cardioversion or catheter ablation.

Atrial Septal Defect

An atrial septal defect (ASD) is a congenital heart defect characterized by an opening in the atrial septum, the wall that separates the right and left atria. This defect allows blood to flow between the atria, which can lead to increased blood flow to the lungs and overloading of the right side of the heart. Treatment may involve surgical repair or catheter-based interventions.

See Also

• Heart
• Cardiac cycle
• Ventricle (heart)

References

• Guyton, A. C., & Hall, J. E. (2016). Textbook of Medical Physiology. Elsevier.
• Lilly, L. S. (2016). Pathophysiology of Heart Disease: A Collaborative Project of Medical Students and Faculty. Wolters Kluwer.