Orthopedic surgeons receive 5 or more extra years of training after school. 1  They specialize in the care of disorders of the bones, muscles, tendons, and ligaments. They are trained to manage joint problems with both operative and non-operative techniques.
What the Immune System Does. The immune (pronounced: ih-MYOON) system, which is made up of special cells, proteins, tissues, and organs, defends people against germs and microorganisms every day. In most cases, the immune system does a great job of keeping people healthy and preventing infections.
Introduction. 1  What is your body made of? Your first thought might be that it is made up of different organsâsuch as your heart, lungs, and stomachâthat work together to keep your body going. 2  Atoms and molecules follow the rules of chemistry and physics, even when they're part of a complex, living, breathing being.