1
00:00:01,920 --> 00:00:06,520
Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hey

2
00:00:06,559 --> 00:00:09,440
Speaker 1: brain Stuff. Lauren bog Obam here with another classic episode

3
00:00:09,440 --> 00:00:13,440
Speaker 1: from erstwhile host Christian Sagar. I admit we originally wanted

4
00:00:13,480 --> 00:00:16,680
Speaker 1: to do this episode Hey because it's interesting, but be

5
00:00:16,680 --> 00:00:19,599
Speaker 1: because we are fans of horror and we wanted to

6
00:00:19,640 --> 00:00:22,200
Speaker 1: demonstrate the episode on YouTube by dumping a bucket of

7
00:00:22,200 --> 00:00:25,919
Speaker 1: fake blood over my head Carry style if you happen

8
00:00:25,960 --> 00:00:27,720
Speaker 1: to look it up. I apologize in advance for what

9
00:00:27,840 --> 00:00:30,200
Speaker 1: counted as my acting ability at the time, but the

10
00:00:30,240 --> 00:00:35,040
Speaker 1: subject remains fascinating. Our blood is always read, even in

11
00:00:35,080 --> 00:00:40,880
Speaker 1: our veins when it looks blue. Here's why, Hey brain Stuff,

12
00:00:40,880 --> 00:00:43,680
Speaker 1: it's Christian Sager. Do you remember in the movie Carry

13
00:00:43,760 --> 00:00:47,760
Speaker 1: where they dumped pig blood on that girl at her prom? Well.

14
00:00:47,800 --> 00:00:51,199
Speaker 1: The Annals of Human Biology actually published an article in

15
00:00:51,240 --> 00:00:55,560
Speaker 1: two thousand twelve showing that humans are excellent detectors of

16
00:00:55,680 --> 00:00:59,120
Speaker 1: pig blood, but we are far less developed at detecting

17
00:00:59,480 --> 00:01:03,440
Speaker 1: human blood. They concluded that human blood has no specific

18
00:01:03,560 --> 00:01:09,080
Speaker 1: smell or appearance that triggers immediate recognition. So blood is

19
00:01:09,120 --> 00:01:12,160
Speaker 1: always red, right, But why does it have to be read?

20
00:01:12,600 --> 00:01:16,440
Speaker 1: Contrary to popular belief, it's not blue when it's in

21
00:01:16,480 --> 00:01:21,120
Speaker 1: our bodies, even when it's deoxygenated. But oxygen is part

22
00:01:21,240 --> 00:01:25,160
Speaker 1: of the color, along with the protein molecule hemoglobin that

23
00:01:25,200 --> 00:01:29,560
Speaker 1: attaches to oxygen it carries from the lungs two muscles

24
00:01:29,600 --> 00:01:33,080
Speaker 1: as blood gets pumped through the human body. And while

25
00:01:33,120 --> 00:01:35,680
Speaker 1: blood is always red, its shade depends on how much

26
00:01:35,680 --> 00:01:39,399
Speaker 1: oxygen it's carrying. For instance, when you cut a person's

27
00:01:39,480 --> 00:01:43,240
Speaker 1: arteries open, they bleed this really bright red blood because

28
00:01:43,240 --> 00:01:48,919
Speaker 1: of the complex formed between hemoglobin, iron, and lots of oxygen.

29
00:01:49,200 --> 00:01:52,240
Speaker 1: But if you look deeper into the circulatory system and

30
00:01:52,320 --> 00:01:55,680
Speaker 1: peered into a vein that was delivering all of its oxygen,

31
00:01:56,040 --> 00:01:59,800
Speaker 1: you would see that the blood is a deeper maroon color.

32
00:02:00,280 --> 00:02:04,640
Speaker 1: So veins they look blue or green mainly because of

33
00:02:04,800 --> 00:02:09,400
Speaker 1: skin and skin pigmentation plays a big role. Since everyone's

34
00:02:09,440 --> 00:02:13,000
Speaker 1: skin is a different color, our veins look different, especially

35
00:02:13,080 --> 00:02:16,799
Speaker 1: because the tissue above our veins scatters red light, but

36
00:02:17,000 --> 00:02:20,880
Speaker 1: let's blue light right on through. Even though veins are

37
00:02:20,919 --> 00:02:24,919
Speaker 1: a reddish brown, they appear to be blue from the outside.

38
00:02:25,400 --> 00:02:28,600
Speaker 1: So is the way human beings perceive color and other

39
00:02:28,680 --> 00:02:32,320
Speaker 1: factor here as well. Yes, researchers have shown that it

40
00:02:32,440 --> 00:02:37,280
Speaker 1: is partially an optical illusion. So light colored skin reflects

41
00:02:37,360 --> 00:02:43,200
Speaker 1: most light and blood absorbs most light, particularly dark deoxygenated blood.

42
00:02:43,480 --> 00:02:46,640
Speaker 1: It reflects a little blue and some red, But since

43
00:02:46,639 --> 00:02:49,600
Speaker 1: the skin surrounding the veins scatters and reflects a lot

44
00:02:49,639 --> 00:02:53,400
Speaker 1: of red light, the veins look way bluer in comparison.

45
00:02:53,680 --> 00:02:57,280
Speaker 1: The ratio is so skewed that it tricks the eye.

46
00:02:57,320 --> 00:03:02,480
Speaker 1: In fact, some animals actually need other colors, like slugs

47
00:03:02,480 --> 00:03:11,080
Speaker 1: and molluscs they believe blue. Today's episode was written by

48
00:03:11,160 --> 00:03:13,640
Speaker 1: Christian and produced by Tyler Clang. For more on this

49
00:03:13,680 --> 00:03:16,160
Speaker 1: and lots of other topics, visit how stuffworks dot com.

50
00:03:16,240 --> 00:03:18,400
Speaker 1: Brain Stuff is a production of iHeart Radio. For more

51
00:03:18,440 --> 00:03:21,800
Speaker 1: podcasts my heart Radio, visit the iHeart Radio app, Apple Podcasts,

52
00:03:21,880 --> 00:03:23,639
Speaker 1: or wherever you listen to your favorite shows.