How blood passes through the capillaries?

The capillaries are the smallest blood vessels in the body, and they play a vital role in the exchange of oxygen and carbon dioxide between the blood and the tissues. The walls of the capillaries are very thin, and they allow the oxygen and carbon dioxide to diffuse across them easily.

Blood enters the capillaries from the arterioles, which are the small arteries that branch off from the larger arteries. The blood pressure in the arterioles is higher than the blood pressure in the capillaries, so the blood is forced through the capillaries.

As the blood flows through the capillaries, the oxygen diffuses from the blood into the tissues, and the carbon dioxide diffuses from the tissues into the blood. The oxygen is carried by the hemoglobin in the red blood cells, while the carbon dioxide is carried by the plasma in the blood.

Once the blood has passed through the capillaries, it enters the venules, which are the small veins that branch off from the capillaries. The blood pressure in the venules is lower than the blood pressure in the capillaries, so the blood flows slowly through the venules.

The venules eventually merge together to form larger veins, which carry the blood back to the heart.

The exchange of oxygen and carbon dioxide between the blood and the tissues is essential for life. The capillaries play a vital role in this exchange, and they are essential for maintaining homeostasis in the body.