CHAPTER FIFTEEN

1. CHAPTER FIFTEEN LESSON EIGHT SKIN, BONES, MUSCLES

2. OBJECTIVES • DESCRIBE WHY YOUR SKIN, BONES, AND MUSCLES ARE IMPORTANT. • DESCRIBE DISEASES OF THE SKIN, BONES, AND MUSCLES.

3. BELLRINGER • IMAGINE WHAT A HUMAN BODY WOULD BE LIKE WITHOUT SKIN, BONES, OR MUSCLES. WRITE A PARAGRAPH ABOUT THE PROBLEMS A PERSON WOULD HAVE—BESIDES JUST AN UNPLEASANT APPEARANCE—WITHOUT SKIN, BONES, OR MUSCLES.

4. ESSENTIAL QUESTION WHY ARE BONES CONSIDERED LIVING TISSUE?

5. DEFINITIONS • SKIN YOUR SKIN IS A PROTECTIVE COVERING FOR YOUR BODY. IT RECEIVES SIGNALS FROM THE ENVIRONMENT, SUCH AS TOUCH OR PAIN. • BONES BONES ARE SOLID STRUCTURES MADE OF PROTEINS, MINERALS, AND CONNECTIVE TISSUE. YOUR BONES GIVE YOU STABILITY. THEY ALSO PROTECT IMPORTANT ORGANS, SUCH AS THE BRAIN AND THE SPINAL CORD. • MUSCLES YOUR MUSCLES ARE TISSUE THAT MAKE IT POSSIBLE FOR YOUR BODY TO MOVE. • BLOOD VESSELS INSIDE YOUR BONES DELIVER NUTRIENTS TO THE LIVING BONE CELLS. BONE MARROW, LOCATED IN THE CENTER OF THE BONE, IS WHERE BLOOD CELLS ARE FORMED. • SKIN SOME SKIN DISEASES, SUCH AS SKIN CANCERS, ARE CAUSED BY EXPOSURE TO SUNLIGHT. OTHER SKIN DISEASES, SUCH AS PSORIASIS, HAVE NO KNOWN CAUSE. • BONES OSTEOPOROSIS IS A BONE DISEASE THAT CAUSES LOSS OF BONE DENSITY, SO BONES BECOME BRITTLE. RICKETS RESULTS FROM A LACK OF VITAMIN D, AND CAN BE TREATED WITH A PROPER DIET. • MUSCLES MUSCULAR DYSTROPHY IS A GROUP OF SEVERAL INHERITED MUSCLE DISEASES THAT CAUSE MUSCLES GRADUALLY TO BECOME WEAK AND DISABLED.