Answer: ensure blood flows toward your heart
Explanation:
These valves are what ensure blood flows toward your heart. Vein valves work hard, against gravity, to bring the blood that flowed down via arteries back up to your heart. When your vein valves are open and healthy, they are able to do their job properly, as the blood is easily able to flow up.
The food chain will mess up.
True Dna is a specialized carbohydrate contained within cells.
