How come when you get blood taken out of your arm since the needle pierces the vein in your arm, you dont bleed internally?
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Anonymous
ANSWERS: 3
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Your arteries and veins are somewhat elastic, and contain things called platelets (not sure on spelling). When the needle pierces your skin, it siphons off some of the blood travelling through the artery/vein and puts it into a bag. The body detects this and your immune system starts to respond to the invasion. When the needle is removed, platelets travel to the skin to form a scab by clotting the blood. Some oozes out to clean the area naturally. Your vein (because of it's elasticity) then closes the gap most of the way, and repairs itself with the help of platelets and its cell wall reproducing. Keep in mind that if you're a hemopheliac then that needle could be your death sentence, but that's for another question. Hope that covers it.
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Sometimes you do. It will cause a terrible bruise when this happens. It happens to me almost everytime I have blood taken.
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G'day Sweetpeah, Thank you for your question. The blood generally clots stopping further bleeding. The donor is normally given a bandage. People whose blood doesn't clot such as haemophiliacs aren't allowed to donate blood. Bleeding does occasionally occur and you are advised to raise pressure, apply a coldpack and contact the Red Cross or blood bank. I have attached sources for your reference. Regards References Wikipedia Blood donation http://en.wikipedia.org/wiki/Blood_donation American Red Cross http://www.givelife2.org/donor/tips.asp
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