Functions of the Musculoskeletal System and Bone Structure

1. Functions of the Musculoskeletal System and Bone Structure

2. Definition • Musculoskeletal system is made up of muscles, bones, and the tissues that connect them. • It functions to provide: • Structure – gives shape and size • Protection – protects fragile tissue • Mineral Reserve - calcium and phosphorus • Blood Cell Production – bone marrow is housed in long bones which produces blood cells

3. Bone Structure • Parts of a long bone • Epiphysis - very ends; covered with articular cartilage • Metaphysis - middle; transition area • Diaphysis - shaft of a long bone

4. Bone Structure • Long bones are known as compact bones • Dense or compact outer shell of the bone • The more force placed on the bone, the thicker this layer will be • Femur – The shaft of the bone will be thicker as this is where the majority of strain will occur

5. Bone Structure • Inside the compact bone is loosely arranged bone called spongy bone • Found only in long bones, not flat bones • Fills only the ends of the bones • Created of spincules that are randomly assorted • Provides strength while making the bone light-weight

6. Bone Structure • The medullary cavity - hollow shaft of the bone • Holds the bone marrow which is the site of blood cell production

7. Bone Structure • Periosteum is a thin connective tissue that covers the bones • Blends into the tendons and ligaments binding them to the bone • Area of the bone covered in cartilage does not have periosteum covering it – Cartilage provides protection • Endosteum is a similar connective tissue that protects open spaces within the bone • Periosteum and endosteum provide the cells needed for repair of damage

8. Bone Structure Ca P • Dried bone is composed of: • 70% inorganic material • Mostly calcium and phosphorus • Provide hardness and strength • 30% organic components • Composed of collagen and cells • Provides a level of elasticity – ability to bend slightly Bone Cell

9. Now a word from our sponsors… Providing you with the terms you need to know! • Oste/o – bone • -blast – embryonic • -cyte – cell • -clast - break Break-Down Dictionary

10. Bone Structure • Three types of bone cells • Osteoblasts – (bone embryo)  young bone cells which lay down collagen matrix • Once encased in matrix  develop into osteocytes • Osteocytes – (bone cell)  maintain the bone matrix • Osteoclasts – (bone break)  allow for minerals to be released from the bone

11. Use it! • Osteoporosis? • Oste/o – bone • -porosis – passage or porous condition • When bones loose the normal density which leads to decreased bone mass • How? • Osteoclasts release minerals into the blood stream as needed, if a bone does not redeposit minerals back into the bone it becomes weak!

12. Use it! • Once a bone becomes to thin due to removal of minerals, it is easier to break! • If caused by disuse of limb (animal in cast)  reversible once the animal begins to use the limb.

13. Bone Structure • Bone is composed of a collection of microscopic units call osteons. • In the center of the osteons there is a canal that hold blood vessels, nerves, and lymphatics • Bone is laid down in circular patterns around this channel • Within this layer are osteocytes that maintain the bone matrix • Many osteons joined together form layers of bone