Gr 5--8--Greeting young "gastronauts" riding in on a lump of mashed potatoes, E, a genial microbe, conducts a detailed tour of the digestive system's anatomical and chemical wonders from the "booming microbial metropolis" of the mouth down to the rectal sphincters. Whether explaining what triglycerides, the uvula, or the liver do or nattering on about the causes and mechanisms of vomiting, flatulence, and constipation, E makes a coherent and informative guide…despite turning out to belong to the not-always-so-benign Escherichia coli clan. Ristaino's cartoon-style mix of fanciful and realistically detailed images offer informative inside views of individual cells, molecules, taste buds, and other tiny locales to go along with all the digestive organs, broad tunnels, and other macrostructures. He also packages fluids like saliva and feces in recognizably shaped squeeze bottles (readers will never look at ketchup the same way again) and by putting faces on the diverse populations of bacteria and archaea that add over four pounds to our weight and outnumber our own cells underscores the fact that we are not individuals but communities. Human figures in rare glimpses of the outside world show some variation in skin color. Like our bodies, this fantastic voyage also has an appendix--with schematic views of the digestive systems of six common animals from cats to cockroaches added on. VERDICT Serious middle school voyagers who go with the densely informational flow will wind up not intellectually constipated but, like E, ultimately, flushed with wonder.--John Peters, Children's Literature Consultant, NY

An illustrated adventure through the human digestive system. The subtitle says it all--no organ or, seemingly, molecule goes unexplored, from the oral cavity all the way to the rectum. The protagonist is a bacterium in the oral cavity named E who accidentally leaves the comfort of its natural habitat (where some 50 billion to 100 billion other bacteria reside) when it's swallowed along with a bolus (or blob of chewed food--one of many vocabulary words defined in context and in a closing glossary). E meets new bacteria, enzymes, and sentient organs along the way who explain their roles in the digestive tract. "My dominion," explains H. pylori, "is the thick gastric mucosa, or mucous membrane." As E moves through the digestive system, a diagram that appears periodically continues to grow. Viola's text clarifies the concepts with the help of Ristaino's illustrations, which also provide humor, and much of what is introduced is reiterated at other points in the graphic novel, aiding retention. While Viola works hard to break down information, he still packs a lot in: "Saliva contains an enzyme called amylase. Amylase breaks down starch, a complex carbohydrate, into simple sugars….And some saliva carries an enzyme called lipase that starts breaking down triglycerides." Magic School Bus graduates ready for a busy, heavy informational load will find this just the ticket. The backmatter also includes brief introductions to the digestive systems of cats, dogs, whales, cows, birds, and cockroaches. A fun and challenging introduction. (Graphic nonfiction. 9-14) Copyright (c) Kirkus Reviews, used with permission.