Capillaries are the smallest of the blood vessels of the circulation system within the body. In fact, capillaries are so small that they cannot be seen with the naked eye. And they are SO small that red blood cells have to go through the capillaries single file. Line up, little blood cells!
Amazingly, there are about 10 billions capillaries. put them end to end and they will be about 25,000 miles long.
But, what are they? And what do they do? Well, the work of the capillaries is very important. The heart pumps blood into the main artery. This blood flows into different arteries and then into the capillary system. The blood in the capillaries deliver oxygen and nutrients to different cells in the body and take on carbon dioxide and waste material to haul away. The blood then flows into the veins which return it back to the heart. From here, the heart takes the blood, that is now loaded with carbon dioxide and other waste, and pumps it into another artery that flows into the capillaries of the lungs.
There, in the lungs, the blood releases its carbon dioxide (that you breathe out) and receives the new oxygen (that you breathe in). This oxygen rich blood is now rushed back to the heart and distributed throughout the body by the capillaries.
So, while your capillaries may be small, they play a very important role in keeping you alive and well. You are indeed, Fearfully and Wonderfully Made
-By Steven McFie