William Harvey experiment: veins and valves [ENG SUB]

1. This is a vein because a vein is in general present near the skin surface. 2. Left finger prevents blood from flowing into the blood vessel between the two fingers. The left finger pushes blood away in the blood vessel between the two fingers. 3. Valve at this point prevents blood from flowing back. 4. Absence of blood in this part causes the blood vessel to disappear.