Capillary vessels are best described as

Capillary vessels are best described as

• A. Fragile divisions of the arterial system that allow contact between the blood and tissue cells
• B. Large vessels that transport blood to the heart
• C. Vessels that carry blood away from the heart
• D. Lymphatic vessels that filter pathogens

Answer: (A)

Capillary vessels are the smallest, thinnest-walled blood vessels, with walls that are essentially a single layer of endothelial cells. This extreme thinness makes them fragile, but it also allows gases, nutrients, and wastes to diffuse directly between the blood and surrounding tissue cells. Because capillaries are so fine, they come into direct contact with virtually every tissue cell, enabling efficient exchange as blood passes through. They connect the smallest arteries (arterioles) to the smallest veins (venules), serving as the primary site where materials are exchanged rather than acting as large transport vessels. Lymphatic vessels belong to a separate system and are not the vessels described here.

Capillary vessels are the smallest, thinnest-walled blood vessels, with walls that are essentially a single layer of endothelial cells. This extreme thinness makes them fragile, but it also allows gases, nutrients, and wastes to diffuse directly between the blood and surrounding tissue cells. Because capillaries are so fine, they come into direct contact with virtually every tissue cell, enabling efficient exchange as blood passes through. They connect the smallest arteries (arterioles) to the smallest veins (venules), serving as the primary site where materials are exchanged rather than acting as large transport vessels. Lymphatic vessels belong to a separate system and are not the vessels described here.