More facts about capillaries (600X)

If you were to lay out all the capillaries in your body end to end, they would stretch for about 60,000 miles! Capillaries play a crucial role in regulating body temperature. When you're hot, they dilate to allow more blood to flow to the skin's surface, where heat can be lost. When you're cold, they constrict to reduce blood flow and conserve heat. The smallest capillaries in the body are called microcapillaries, and they can be as small as one micron in diameter. That's about 1/100th the width of a human hair! Capillaries also play an important role in the immune system, allowing white blood cells to move in and out of the bloodstream to fight infection and inflammation. Capillaries are essential for wound healing, as they bring oxygen and nutrients to the site of an injury, and carry away waste products and debris. Some diseases, such as diabetes, can damage the walls of capillaries, leading to poor circulation and a variety of health problems.