A capillary is a microscopic blood vessel that connects small arteries and veins and is a major site of exchange between blood and surrounding tissues.
Capillaries have extremely thin walls, usually consisting of a single layer of endothelial cells, allowing substances such as oxygen, carbon dioxide, nutrients, hormones, and metabolic waste products to move between blood and tissues.
Networks of capillaries are found throughout most tissues and connect the arterial and venous sides of the circulation.
QUICK FACT
Capillaries are much smaller than arteries and veins, but they are essential for delivering oxygen and nutrients to cells and removing waste products.
COMMONLY CONFUSED WITH
- Artery: carries blood away from the heart.
- Vein: carries blood toward the heart.
- Blood vessel: the broader term that includes arteries, veins, and capillaries.
SEE ALSO