What type of blood vessel is primarily involved in gas exchange in tissues?

Capillaries are the primary type of blood vessel involved in gas exchange within tissues. They are the smallest blood vessels in the body, with a very thin wall that allows for efficient diffusion of gases, nutrients, and waste products between the blood and surrounding tissues. The walls of capillaries are only one cell thick, facilitating the exchange of oxygen and carbon dioxide directly with the tissue cells.

This process of gas exchange occurs as oxygen diffuses from the blood within the capillaries into the tissues, while carbon dioxide moves from the tissues back into the blood. The extensive network of capillaries throughout all tissues ensures that every cell can receive the oxygen it needs for metabolism and dispose of carbon dioxide efficiently. Other blood vessels, such as arteries and veins, play different roles in circulation; arteries carry blood away from the heart under high pressure, and veins return blood to the heart, but they are not directly involved in the exchange processes at the tissue level.