GK
GENERAL SCIENCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Veins in the brain swell.
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Veins in the lower extremity shrink.
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Valves of veins in the legs fail to function properly.
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Valves of veins in the heart fail to function properly.
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Detailed explanation-1: -Weakened valves, also called incompetent valves, within the veins might cause varicose veins. The weakened valves let blood pool in the veins instead of traveling to the heart.
Detailed explanation-2: -Varicose veins are twisted, swollen veins near the surface of the skin and occur when weak or defective valves allow blood to flow backward or stagnate within the vein. Chronic obstruction of the veins can also cause varicose veins, but in most cases no underlying abnormality can be identified.
Detailed explanation-3: -The blood is prevented from flowing backwards by a series of tiny valves that open and close to let blood through. If the valves weaken or are damaged, the blood can flow backwards and collect in the vein, eventually causing it to be swollen and enlarged (varicose).