Functions of the Musculoskeletal System and Bone Structure

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 5/18/2021 2

Bone Structure n n Parts of a long bone Epiphysis - very ends; covered with articular cartilage Metaphysis - middle; transition area Diaphysis - shaft of a long bone 5/18/2021 3

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 5/18/2021 4

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 5/18/2021 5

Bone Structure The medullary cavity - hollow shaft of the bone Holds the bone marrow which is the site of blood cell production 5/18/2021 6

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 5/18/2021 7

Bone Structure a P C 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 5/18/2021 l l e C e n Bo 8

Now a word from our sponsors… Break-Down Dictionary Providing you with the terms you need to know! Oste/o – bone -blast – embryonic -cyte – cell -clast - break 5/18/2021 9

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 5/18/2021 10

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! 5/18/2021 11

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. 5/18/2021 12

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 5/18/2021 13