Answer:
Capillaries
Brief explanation:
These thin blood vessels that connect the arteries and the veins are called capillaries. Their thin walls allow oxygen, carbon dioxide, nutrients and waste products to pass to and from the tissue cells.
Step-by-step explanation:
There are capillaries in the lungs and in every organ and tissue in the body. As mentioned above, they act as the body's exchange vessels. Gases, nutrients, water, and wastes pass back and forth between body cells and the bloodstream across the thin walls of capillaries. The walls of capillaries are made up of very thin, flat cells. The capillary walls contain large structures such as red blood cells inside the capillary. Other substances including as oxygen, carbon dioxide, glucose (sugar), and water can pass through