The second statement best explains the type of blood vessel and the function of these vessels' valves - <span>These are veins, which prevent the backflow of blood because the walls have little muscle to pump blood back to the heart.
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Veins are large blood vessels which carry blood back to the heart. <span>Veins have a system of valves to prevent back-flow.</span>
Answer:
I do not think it is possible. You can loose weight by not consuming anything (not receiving proper nutrition) and it can be damaging to the body. Also without the proper nutrients is would be hard to maintain fitness because you would lack energy. If you don't have nutrition your hair,nails,bones and skin with become weak and you will feel drained and tired all the time. Yes you could lose weight but your body wouldn't be healthy.
Explanation:
Stretching exercises will help:build strength,build endurance and prevent injury
not enough info to answer