Flow of Blood through your Heart
The most critical detail about the cardiac (cardiovascular) system is that it operates as a closed, pressurized loop driven by a synchronized double pump. It is responsible for continuously delivering oxygen, nutrients, and hormones to tissues while carrying away metabolic waste.
The system works by splitting the heart into two distinct circuits running at the exact same time: The Right Side (Pulmonary Circuit): Receives oxygen-depleted, waste-filled blood from the body and pumps it under lower pressure to the lungs to pick up oxygen and release carbon dioxide. The Left Side (Systemic Circuit): Receives that freshly oxygenated blood from the lungs and pumps it under much higher pressure through the thick walls of the left ventricle out to the rest of the body. One-way valves prevent any backward leakage, and a built-in electrical pacemaker (the SA node) fires rhythmic shocks to ensure the chambers contract in perfect order.