Question #12499

1 Answer
MeneerNask
Mar 22, 2015

Because part of the liquid part (the plasma) filters through the walls of the blood vessels.

Especially the capillary veins have very thin walls, through which a lot of plasma escapes (helped by blood pressure). Most of it is reabsorbed into the blood flow further on.

But about 3 litres a day is sent back to the heart by the lymphatic system. See picture below (wikipedia).

enter image source here

Related questions
Impact of this question
262 views around the world
You can reuse this answer
Creative Commons License