Final answer:
The right atrium receives deoxygenated blood from the body and pumps it to the right ventricle, while the left atrium receives oxygenated blood from the lungs and sends it to the left ventricle.
Step-by-step explanation:
The right atrium and left atrium play crucial roles in the blood circulation within the heart. The right atrium receives deoxygenated blood from the body via the superior and inferior vena cava and pumps it to the right ventricle through the tricuspid valve. Conversely, the left atrium receives oxygenated blood from the lungs through the pulmonary veins and sends it to the left ventricle through the mitral valve (bicuspid valve). Valve function is vital in preventing backflow and ensuring unidirectional blood flow, which is critical for efficient circulation.
The atria play a significant role in blood pressure regulation as well. During the cardiac cycle, the atria contract (atrial systole) to push blood into the ventricles; this is followed by the ventricles contracting (ventricular systole) to distribute blood to the lungs and body, respectively. Proper synchronization of atrial and ventricular contractions is essential for maintaining consistent blood pressure. However, the atria do not directly secrete hormones that affect blood pressure; this is the role of the endocrine system.