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.
The body is made up from millions of tiny cells. Different parts of the body, such as organs, bones, muscles, skin, and blood, are made up from different specialised cells. All cells have a centre called a nucleus. The nucleus in each cell contains thousands of genes which are made up from a chemical called DNA.