The right atrium is one of the four chambers of the heart and plays a key role in the circulatory system. Here’s a breakdown of its structure and function:
Structure:
- Location: The right atrium is located in the upper right part of the heart, above the right ventricle.
- Walls: The inner walls are smooth, except for a small portion that contains pectinate muscles, which are ridged structures.
- Key Openings:
- Superior Vena Cava: This vein brings deoxygenated blood from the upper body (head, arms, etc.) into the right atrium.
- Inferior Vena Cava: This vein carries deoxygenated blood from the lower body into the right atrium.
- Coronary Sinus: This is a vein that brings deoxygenated blood from the heart muscle itself into the right atrium.
- Tricuspid Valve: This valve separates the right atrium from the right ventricle and controls blood flow from the atrium to the ventricle.
Function:
- Receiving Deoxygenated Blood: The right atrium receives deoxygenated blood from the body via the superior and inferior vena cavae and the coronary sinus.
- Pumping Blood into the Right Ventricle: When the right atrium contracts (a phase called atrial systole), it pushes the blood through the tricuspid valve into the right ventricle.
- Regulation of Blood Flow: The tricuspid valve ensures that blood flows only in one direction—from the right atrium to the right ventricle—preventing backflow.
In summary, the right atrium acts as a receiving chamber for deoxygenated blood and a preparatory chamber for pumping that blood into the right ventricle, which then sends it to the lungs for oxygenation.