Blood vessels are the primary structures that play a crucial role in the circulating of blood, nutrients, and oxygen. The major blood vessels are the arteries, veins, and capillaries.
The arteries deliver oxygen-rich blood to different parts of the body, with some other nutrients. Veins are thicker blood vessels that deliver deoxygenated blood from different parts of the body to the heart.
The vessels when narrow the diameter for the exchange of materials are termed as capillaries.
The capillaries are extremely thin and minute vessels, where the exchange of gases and nutrients takes place at the cellular level. The pressure in the capillaries is low and has thin walls.
On the other hand, arteries and veins have high pressure and thick walls, which makes them unsuitable to exchange materials.
Thus, the capillaries are the site where the exchange of materials occurs.
To know more about blood vessels, refer to the following link:
https://brainly.com/question/14617611
