Blood carries oxygen, food, and water to living tissues; it carries waste to the kidneys, liver, and lungs; it maintains the police presence of the immune system and carries vital hormonal signals all throughout the body; it even has pressurized hydraulics and helps regulate body temperature, all within a narrow range of pH values (a tenth of a point, between 7.35 & 7.45). Your body is basically a sac for your blood, the universal fluid that ties every part and function together. They Might Be Giants explain it in broad strokes and easy language in The Bloodmobile:
Blood's very ubiquity made this an unusually research-intensive entry, and there's so much interesting stuff that I want to take it by parts. This weekend - and since I'm not spending all my time reading about blood, I'll actually have time to write about it, so it will actually be this weekend - I'll write about blood's role in respiration and homeostasis, ferrying oxygen and carbon dioxide hither & yon, and regulating pH levels & body temperature. Next Wednesday, I'll write about the immune system, which I would normally give its very own entry except for the fact that it all kind of takes place within the blood. And the following weekend, I'll talk about blood technologies and diseases, because they are also fascinating. Stay tuned!