Concept in Definition ABC

A atrium is a cavity that is part of the heartThere are two in total, the right atrium and the left atrium.

The atria are the cavities to which the blood comes from the circulation General and pulmonary, once filled they contract thus passing this fluid towards the ventricles. They are also the structures where the heart's natural pacemaker is located.

Structure and function of the atria

The atria are located behind the ventricles, they are smaller than these, they have a cubic shape with six walls formed by muscle tissue, inside are lined by a thin layer of cells called endocardium.

They are separated from each other by the interatrial septum and communicate with the ventricles through the atrioventricular valves, which are two, the right atrium communicates with the ventricle right through the tricuspid valve, while the left atrium is separated from the left ventricle by the mitral valve.

The right atrium receives blood from the body through the superior and inferior vena cava, equally receives blood from the heart muscle through a heart vein known as the sinus coronary.

The left atrium It receives blood from the pulmonary circulation through the pulmonary veins, which are four in total, two on the right and two on the left.

The electrical activity of the heart begins in the atria

The right atrium contains in its posterior wall a important structure known as node sinus, it contains highly specialized cells capable of generating repeated depolarizations that act as a pacemaker that allows a activity Automatic that determines how often the heart beats.

Starting from the sinus node, the impulse electrical travels to the wall of both atria and subsequently to the ventricles after a brief delay in driving what happens in a second node, the atrioventricular node.

The heart's pumping activity takes place in two phases, diastole in which it fills with blood and systole in which it expels blood. During diastole, blood passes from the atria to the ventricles, once full, systole begins, which closes the valves atrioventricular arteries causing blood not to return to the atria but rather to exit the heart through the aorta and arteries pulmonary. While the ventricles are contracting in systole, the atria fill with blood to start a new cycle.

Photos: iStock - Ugreen / Tigatelu