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.
Endocrine System. The endocrine system is made up of a group of glands that produce the body's long-distance messengers, or hormones. Hormones are chemicals that control body functions, such as metabolism, growth, and sexual development.he muscular system is made up of tissues that work with the skeletal system to control movement of the body. Some musclesâlike the ones in your arms and legsâare voluntary, meaning that you decide when to move them. Other muscles, like the ones in your stomach, heart, intestines and other organs, are involuntary.