How does blood circulate in a closed circulatory system?

In a closed circulatory system, blood circulates through a network of blood vessels, driven by the heart's pumping action.

In more detail, a closed circulatory system is one in which blood is confined to vessels and is distinct from the interstitial fluid. This system is found in humans and other vertebrates. The heart, the main organ of this system, acts as a pump that propels the blood throughout the body. The blood vessels, which include arteries, veins, and capillaries, serve as the pathways for the blood to travel.

The process begins when the heart contracts, pushing oxygen-rich blood into the arteries. These arteries then branch out into smaller arterioles and further into tiny capillaries. It is in these capillaries where the exchange of oxygen, nutrients, and waste products occurs between the blood and the body's cells.

Once the oxygen is delivered and waste products are picked up, the blood, now oxygen-poor, returns to the heart through the venules, which merge to form veins. The veins carry the blood back to the heart, where it is pumped to the lungs to be oxygenated again. This entire process is known as systemic circulation.

In addition to systemic circulation, there's also pulmonary circulation, which is the part of the circulatory system that carries deoxygenated blood away from the heart, to the lungs, and returns oxygenated blood back to the heart.

The closed circulatory system is a highly efficient method of transporting nutrients and oxygen to cells and removing waste products. It allows for faster blood flow and higher blood pressure, which enables the blood to reach all parts of the body, even those farthest from the heart.