The body’s transit system
The bloodstream, in Isaac Asimov’s words, is the indefatigable transit system of the body, with special tricks for carrying oxygen from lungs to cells and carbon dioxide from cells to lungs; for carrying nitrogen wastes to the kidneys and the products of digestion to the liver; for carrying sugars, lipids, and proteins to all cells; or carrying ions, hormones and vitamins wherever needed; for distributing heat where necessary; for bringing the battle reserves to the point of the outside invasion dangers. And to top it all off, it is self-sealing and plugs its own leaks.
It is difficult to imagine a fluid so versatile and so useful—one that has so many widely diverse duties to perform and performs them so well. In The Bloodstream, Dr. Asimov details step by step the manifold activities of blood and the marvels it performs.
This is an odd little book.
Like Asimov’s fiction, his non-fiction tends to belong to well-defined series: the F&SF essay collections, the Houghton-Mifflin histories, the Abelard-Schuman science juveniles, the "Guide" books, and so on. This is among the exceptions, and is focused on an unusually narrow topic, besides.
Actually, being a book by Asimov, it manages to cover a fair amount of ground regarding basic physiology and biochemistry, despite being (in theory) about blood alone. As one would expect, it covers the ground thoroughly and well. Indeed, its main drawback is that, unlike some other of Asimov’s books, it doesn’t really stand out for good or ill, or for any particular reason.