The purpose of your skeleton seems simple enough. After all, if you didn’t have one, you’d be as saggy as a beanbag chair and a lot less fun. But as you’ll discover, your skeleton isn’t just a handy place to hang your body. It’s actually a hard-working team member that helps you out in several ways:
• Protection. Your bones provide rigid pieces of body armor that protect your critical squishy parts. The best examples of this defense are your skull (which wraps your brain in a non-removable helmet), your spinal column (which sheaths the central highway of your nervous system), and your breastbone and rib cage (which deflect damage away from internal organs like your heart and lungs).
• Movement. As you saw in Chapter 3, your muscles are your body’s real movers and shakers. But muscles need to act on something to produce movement, and that “something” is your bones. Your muscles pull them like the levers of an intricate machine.
• Storage. Your bones are a reservoir of minerals like calcium, which your nervous system and muscles need to function. For example, if your blood doesn’t have a bare minimum of calcium, calcium will gradually leech out of your bones and into your blood. Some bones also store a last-ditch deposit of fat, which they keep in their hollow core.
• Production. As you’ll see in the next section, bones don’t just lie there lifelessly. They house a busy factory that creates blood cells.
Men and women have subtly different skeletons. On average, women have narrower shoulders, shorter arms, and wider hips than men, so women are less suited to actions like throwing and running, but have better stability and a lower center of gravity. There are also a number of subtle differences between male and female skulls. Women’s skulls, for example, tend to be less angular, and they have a less pronounced, softer chin. In a random face-recognition test, most people can quickly separate the women from the men.
Blood cells are tiny cells that circulate in your bloodstream. They play several essential roles. Red blood cells carry life-sustaining oxygen throughout your body. White blood cells produce antibodies that battle infection. Platelets create clots that prevent your blood from leaking out of damaged skin. Without any one of these players, you’d be in serious trouble.
Source of Information : Oreilly - Your Body Missing Manual