What, exactly, do you know about your body? Do you know how your immune system works? Or what your pancreas does? Or the myriad -- and often simple -- ways you can improve the way your body functions?

This full-color, visually rich guide answers these questions and more. Matthew MacDonald, noted author of Your Brain: The Missing Manual, takes you on a fascinating tour of your body from the outside in, beginning with your skin and progressing to your vital organs. You'll look at the quirks, curiosities, and shortcomings we've all learned to live with, and pick up just enough biology to understand how your body works. You'll learn:

That you shed skin more frequently than snakes do
Why the number of fat cells you have rarely changes, no matter how much you diet or exercise -- they simply get bigger or smaller
How you can measure and control fat
That your hair is made from the same stuff as horses' hooves
That you use only a small amount of the oxygen you inhale
Why blood pressure is a more important health measure than heart rate -- with four ways to lower dangerously high blood pressure
Why our bodies crave foods that make us fat
How to use heart rate to shape an optimal workout session -- one that's neither too easy nor too strenuous
Why a tongue with just half a dozen taste buds can identify thousands of flavors
Why bacteria in your gut outnumbers cells in your body -- and what function they serve
Why we age, and why we can't turn back the clock