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The Sound of Science - 'Coagulation'


Newt: You're listening to The Sound of Science on WNIJ. I'm Newt with NIU STEAM.

Becky: And I'm Becky continuing our investigation of blood, we're going to talk about how long blood lasts outside the body. Once you give blood, what's the shelf life of your donation?

Newt: The first thing to consider is what happens to blood when your body detects an injury. If you've ever gotten a cut, which I'm assuming is most everyone, then you know, you don't usually just bleed forever. Most people bleed for a short time and then their blood hardens over the injury and forms a scab. This process is called coagulation.

Becky: Basically, your body is very interested in keeping itself alive and when a foreign tissue enters the bloodstream, your body knows that something has gone wrong, that foreign tissue triggers a series of chemical reactions that activate platelets that stick to your blood cells to form a sort of dam at that place of injury.

Newt: So when a needle enters your vein to collect a donation, what's stopping your blood from trying to make a protective scab out of itself, the vials or bags that your blood is deposited into for a donation contain a very special substance with a very specific purpose of making sure your platelets don't activate.

Becky: Under normal circumstances red blood cells can survive around 115 days, but there's no way of only taking brand new cells during donation, that would be wild. But one of the major reasons donated blood doesn't last that long is because of the substance use to stop coagulation. Different kinds of anticoagulants impact how long donated blood last, but the accepted rage is around 35 to 42 days.

Newt: Which is why blood donation is an ongoing process. If there's a natural disaster, blood supplies can get depleted incredibly fast. You'll likely see more calls to donate blood during those times since it's not like we have an enormous supply of blood at all times.

Becky: Plasma lasts much longer. But that's a different episode.

Newt: You've been listening to The Sound of Science on WNIJ, where you learn something new every day.

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