how do veins prevent the backflow of blood?
370378
valves inside the vein open and close with the beat of the heart that pushes the blood thru the veins. With one beat the valve opens and one it closes with the closing of the valve the blood cannot backflow.  When it does it causes things like a heart murmur
141075
they help keep the artieries and blood vessels to and from the heart from clogging and they help with your blood pressure..
972435
The Aortic valve close or prevents a back flow of blood during diastole at this same time the the mital valve is open as the at atrium is contracting.
360844
Wear sports elastic support hose sold by chemist, ( used by sportsmen for ankle and elbow injuries etc etc ) this will also help prevent DVT (deep vein thrombosis ) caused by long haul flights.
1082725
My grandma gets those and they're hereditary so, I've researched how to prevent them.  Exercising and keeping your legs elevated are the best ways.  However, once you get them, things like Vein Away Plus barely reduce the appearnce of them.  Surgery is the only way to get rid of them in a noticeable way.
1008428
Veins carry deoxygenated blood from the organs and tissues back to the heart.\nDeoxygenated blood from the body enters the right atrium through two great veins, the superior vena cava which drains the upper part of the body and the inferior vena cava that drains the lower part which drains the portal cyrculation too full with nutrients to nourish the body.
400677
pins and needles.  Its when you have been leaning on a part of the body for a long time and the circulation of blood gets cut off, it feels like your arm or legs dead but its not, a tip to get rid of the pain quickly is to wriggle your fingers and toes as fast as you can, this will help the circulation quickly be back to normal.  (They advise when you sat or standing in the same spot for a long time to occasional move about, the circulation could be cut off so much- that the blood actually starts to clot, this condition is then called deep vein thromobolis.)
42377
Larger sized veins require less blood pressure to move blood, and therefore put less strain on the heart.\n\nThey probably have healthier hearts, yes, but also their hearts are under less stress than the average person.
2373
Generally there are 2 reasons why a part of your body might lack blood, physical and chemical.  Physical reasons might be that the part of your body may be too tight to allow for good circulation.  In this case, you must stretch (eg. yoga or pilates) and exercise to loosen up that area.  Doing heat pack will also help to aid the blood flow temporarily.  One important thing to remember though is that the source of tightness might be completely unexpected.  If you have cold hands, it may be more helpful to stretch your calves or your shoulders depending on your body structure rather than the hand itself.  You must remember to treat your body as a whole.  Chemical reasons could come from your diet or the air you breathe or any other intake (eg. tobacco or drugs).  This could alter the chemical make up of your bloodstream.  In this case, what you would have to do is to remove the chemical that is causing the problem.  What part of your body is lacking sufficient blood?
663082
I will take a good guess and say your a power lifter, or some type of weight lifter.\n\nWhen you strain at lifting weights, your veins will expand, so that more oxygen can go through them, to your muscle tissues, so you dont have oxygen deprivation.  \n\nAlso you put a strain on your circulatory system when you power lift, as it makes your heart rate go up, and if  you are straining a muscle, and the blood cant go "into" the muscle, it has to back up into the vein, thus expanding it to large proportions...(especially those nearest the skin).\n\nJesse
824219
Arteries are major vessels that carry blood away from the heart.  Veins are major vessels that carry blood toward the heart.   Blood pressure is less when carried toward the heart, therefore your answer is artery=larger.  The more pressure needed , a larger part it will be  Veins are thinner and less resistant to blood flow...
584848
I've got help for you! There is a vitamin called "Horse Chestnut."  No, it's not made from horses, it comes from a plant with that name. Anyway, it been shown to help diminish varicose veins and promote circulation. Do a search online and you can read more about it what it does, and you can also order it.
880484
Drink plenty of water and don't smoke cigarettes (the worst for blood flow)or drink alcohol. Also Aerobic exercise will make your lungs better able to get oxygen into the bloodstream.
249298
All arteries carry oxygenated blood and all veins carry unoxygenated blood except for in the pulmonary circuit, where the pulmonary arteries carry unoxygenated blood from the heart to the lungs, and the pulmonary veins carry oxygenated blood from the lungs back to the heart.
968702
A cleanly severed vessel is less likely to clot, therefore less likely to stop the blood flow. A crushed or mangled vessel has more places for the clot to form, so it could potentially stop the bleeding. Think of it like a garden hose - a nice clean cut gets a lot of water thrugh it. A mangled end still lets water out, but it impedes the flow. The slower the flow, the better chance of clotting (plus a slower flow means less blood loss).
1169770
You are not getting enough blood flow to your feet.  Try working out barefoot.  The shoes protect your soles but allow you to put too much strain on your calves and thighs where the blood flows.  Bare feet will give you the feedback to cut back on the pressure to the upper legs.  Good Luck!
390085
Two veins which carry oxygenated blood from the mother to the baby and one artery which carries the deoxygenated blood away from the baby.  In between these vessels is Wharton's jelly which keeps the vessels from collapsing