Does blood only run through veins and arteries or is it all over our bodies?

Question

If blood is only in veins and arteries, how come you bleed when you cut yourself?

Answer 1

because it obviousely doesnt just run in our vains and arteries

Answer 2

You forgot capilliaries, the really tiny blood vessels that connect arteries and veins. there are more capillaries (based on length) than arteries or veins.  A capillary is generally only as large as a single red blood cell.  Ther are ALL OVER our bodies.

And you DON'T always bleed when you cut yourself.  Ever had a paper cut??  You DO have to cut a vessel (usually a capillary -- in fact MANY of them) before you start to bleed.

So far as blood cells go, the system is "closed". That means that the blood (in general) always stays in the arteries, veins, and capalliaries.

But there are other parts of the blood, like plasma and antibodies.  This stuff, alogn with white blood cells, can get out of the arteries and veins.  So we ALSO have the Lymphatic system, which is kind like the drain pipe of our system.  It serves to collect these extra fluids and dead cells and dead germs and stuff like that, and cycle them back through the liver (I think . . .)

Maybe you've heard of the Lymph Nodes in you armpits and groin?  Sometimes bacteria and/or viruses get into the lymph system and collect in the lymph nodes.  When this happens it is very painful.