What is the right atrium?
The right atrium is one of the four chambers of the heart. It is located in the upper right corner of the heart, superior to the right ventricle. The right atrium receives deoxygenated blood from the body through the inferior and superior vena cava and communicates with the right ventricle to help transport it through the tricuspid valve to the lungs to be oxygenated.
The heart is an organ that is divided into several parts, which help perform its main function: to carry oxygen-rich blood to the rest of the body (cells, tissues and organs) in order to feed them, and receive carbon dioxide enriched blood to be sent to the lungs, where the oxygen exchange takes place.
It is comprised of two atria and two ventricles. The atria are the two upper chambers of the heart, separated from the atrial septum. As an infant, a small hole in the atrial septum is known as the foramen ovale and it allows blood to flow straight through to the left atrium, bypassing the nonfunctional lungs of fetus, since the baby receives oxygen and nutrients directly from the mother through the placenta. At birth, a thin fibrous tissue moves to cover the foramen ovale and prevent the flow of blood between the atria. This is known as the fossa ovalis. Once born, lungs become necessary and the connection between the two atria closes.
The left and right atria are not symmetrical and differ in location, size and shape. They communicate with the corresponding ventricles, and differ from them in a sense that blood from the ventricles is pushed out of the heart rather than entered into it.
What function does the right atrium serve?
The right atrium is responsible for receiving deoxygenated blood from the body through the vena cava and pumping it into the right ventricle, to be sent to the lungs, where it becomes oxygenated. Oxygenated blood (arterial blood) travels towards organs and tissues in the body through the aorta, the artery that carries nourishment to the whole body and further splits into smaller and smaller branches and capillaries. Carbon dioxide enriched blood returns to the heart through the veins, which transform it to oxygen. Thus, the right atrium is known as the first “station” of arrival of deoxygenated blood.
Apart from being the first structure to receive blood returning from the body, it is also contains the sinoatrial node (SA) which acts as a natural pacemaker of the heart. It triggers electrical impulses that coordinate the heartbeat and control its rhythm as well as motivates other cardiac muscle cells to contract. The AV node takes signals from the sinoatrial node (SA), slow the signal down, regulate it, and finally send electrical impulses from the atria to the ventricles. This in turn helps sustain a normal heart rate in order to maintain blood pressure, oxygen and carbon dioxide levels.
Not only is the right atrium the foundation of primary cardiac rhythm, it is also an important feature in the field of abnormal rhythms. A majority of cardiac electrophysiology procedures in one way or another are likely to involve the right atrium.
