Enceladus: Hello dear friends! Welcome to our podcast. I'm Enceladus, and with me today is Erinome. Today, we’re going to talk about a super interesting question: Why is donating 400ml of blood totally safe, but losing 400ml of blood in an accident can be really dangerous? Erinome, have you ever thought about this?  

Erinome: Oh, yes! I saw this question online last week, and I was so confused. Like, 400ml is 400ml—why the big difference?  

Enceladus: Let’s start with blood donation first. Do you know what happens before someone donates blood?  

Erinome: Um… I think they check if you’re healthy, right? Like, your body must be okay to donate.  

Enceladus: Exactly! The news says before donating, doctors check your blood pressure and blood tests. They make sure you’re a healthy person—no big illnesses. Only healthy people can donate, you know?  

Erinome: That makes sense. And how do they take the blood? Fast or slow?  

Enceladus: Slow! It’s a “slow operation” in the hospital or a blood donation car. The 400ml is taken slowly, so your body has time to adjust. For example, your blood vessels can get smaller, and body fluids can fill the space. So your heart and brain still get enough blood.  

Erinome: Oh! So 400ml is about 8% of an adult’s total blood. That’s not too much, and the slow process helps the body adjust.  

Enceladus: Yes! And after donating, they even give you snacks—like bread, ham, milk. Some people get a纪念包 (jinian bao)—a gift bag! I read a story: a person was very poor when young. They had only 10 yuan for a week, eating馒头 (mantou) and pickles. Then their friend donated blood and got a pink bag, bread, and milk. They wanted the bag, so they donated too!  

Erinome: Oh wow! That’s a sad but cute story. Did they donate a lot?  

Enceladus: Yes! They donated 2000ml in total, but in small parts—like 200ml, then 200ml, then 400ml each time. They were young, so after donating, they could even go shopping! No problem at all.  

Erinome: That’s amazing. And they’re still friends now, right? The story said the friend bought them螃蟹 (pangxie) this year!  

Enceladus: Aww, yes! Hard times make good friends. Now, let’s talk about losing blood in an accident. Why is that different?  

Erinome: I think it’s sudden! Like, if you get a big cut, the blood comes out fast, not slow.  

Enceladus: Exactly! The news calls it “uncontrollable”. For example, if you have a wound from an accident, 400ml might be lost in just a few minutes. Your body can’t adjust that fast.  

Erinome: Oh no! So your blood pressure drops suddenly. What happens then?  

Enceladus: Your brain and heart need blood to work. If they don’t get enough, you’ll feel dizzy, maybe pass out. If you don’t get help quickly, it could be dangerous.  

Erinome: That sounds scary. Are there other reasons? Like, does the accident bring more problems?  

Enceladus: Yes! When you lose blood in an accident, there’s usually a wound. The wound might get infected, or you might hurt your organs. It’s like “snow adding to frost”—making the danger worse.  

Erinome: Oh right! So donating blood is just losing blood, but losing blood in an accident has other injuries. That makes it more dangerous.  

Enceladus: Exactly! And another thing: people who donate are healthy—no other illnesses. But people who lose blood in accidents might have other health problems, so their bodies can’t handle it as well.  

Erinome: I remember another story: a student tried to donate 300ml, but fainted at 220ml. Why?  

Enceladus: Oh, maybe because everyone’s body is different. The news says young people can donate, but they should “know their limits”. Like, if you’re too thin or not feeling well that day, you might not handle it.  

Erinome: So even with donation, we need to be careful. But overall, donation is safe for healthy people.  

Enceladus: Yes! Because it’s controllable: healthy, slow, with doctors watching. But losing blood is uncontrollable: sudden, fast, with wounds. That’s the big difference.  

Erinome: So to sum up: donating 400ml is safe because it’s planned, slow, and for healthy people. Losing 400ml is dangerous because it’s sudden, fast, and often with other injuries.  

Enceladus: That’s right! So next time someone asks, you can say: “Controllable vs Uncontrollable!”  

Erinome: Haha, easy to remember! And donating blood helps others—it’s a good thing. Just follow the doctors’ advice.  

Enceladus: Exactly! Okay, dear friends, that’s all for today. We hope you learned something new. Remember: donate blood safely, and stay safe from sudden blood loss. Thanks for listening, and we’ll talk again next time! Bye!  

Erinome: Bye!