Final answer:
The heart's blood flow sequence starts in the right atrium, goes to the right ventricle, then to the lungs, back to the left atrium, into the left ventricle, and finally out to the body. This process is controlled by the cardiac cycle of electrical impulses causing contraction and relaxation of the heart muscles.
Step-by-step explanation:
The human heart consists of four chambers through which the blood flows in a precise sequence. The pathway begins with the right atrium receiving deoxygenated blood from the body. As the atrium contracts, this blood flows through the tricuspid valve into the right ventricle.
Once filled, the right ventricle contracts, sending blood through the pulmonary valve into the pulmonary arteries and on to the lungs for oxygenation.
Oxygenated blood returns to the heart via the pulmonary veins into the left atrium. Upon contraction of the left atrium, the blood flows through the mitral valve into the left ventricle. Finally, the left ventricle contracts, propelling the blood through the aortic valve and into the aorta for distribution throughout the body.
The cardiac cycle is regulated by a series of electrical impulses that cause the heart muscles to contract (depolarization) and relax (repolarization), maintaining a synchronized rhythm that ensures steady blood flow and proper cardiac function, which can be observed in an ECG (electrocardiogram).