Skeletal System PDF

CHAPTER 4 BONE AND SKELETAL SYSTEM OBJECTIVES:  Define functions of the skeletal system  Recognize how to classify types of bones and their structure  Identify types of fractures: bone repair  Identify the balance between exercise, nutrition, hormones and bone tissue SKELET...

CHAPTER 4 BONE AND SKELETAL SYSTEM OBJECTIVES:  Define functions of the skeletal system  Recognize how to classify types of bones and their structure  Identify types of fractures: bone repair  Identify the balance between exercise, nutrition, hormones and bone tissue SKELETAL SYSTEM  Four components: 1. Bones 2. Cartilage 3. Tendons 4. Ligaments FUNCTIONS OF THE SKELETAL SYSTEM  Supports the body  Protects internal organs  Facilitates movement  Stores and releases minerals and fats  Produces blood cells BONE CLASSIFICATION  BONE –osseous tissue - hard, dense connective tissue - consists of extracellular bone matrix and bone cells 1. Long bones 2. Short bones 3. Flat bones 4. Irregular bones 5. Sesamoid bones GROSS ANATOMY OF THE BONE  Bone Matrix - 35% organic + 65% inorganic material.  Organic – collagen (flexible strength)  Inorganic – hydroxyapatite (weight-bearing strength)  Parts of a Long Bone 1. Diaphysis - the tubular shaft that runs between the proximal and distal ends of the bone.  Medullary cavity - hollow region in the diaphysis which is filled with yellow marrow. 2. Epiphysis - wider section at each end of the bone, filled with spongy bone.  Epiphyseal plate (growth plate)  Endosteum - delicate membranous lining where bone growth, repair, and remodeling occur.  Periosteum – fibrous membrane that covers the outer surface of bone - contains blood vessels, nerves, and lymphatic vessels that nourish compact bone  Two layers of compact bone and the interior spongy bone work together to protect the internal organs. BONE MARKINGS  Articulation - where two bone surfaces come together  Projection - an area of a bone that projects above the surface of the bone  Hole - an opening or groove in the bone that allows blood vessels and nerves to enter the bone. BONE CELLS  Osteoblasts - bone cell responsible for forming new bone and is found in the growing portions of bone  Osteocytes - primary cell of mature bone  Osteogenic Cells - undifferentiated with high mitotic activity and they are the only bone cells that divide.  Osteoclasts - responsible for bone resorption, or breakdown BONE TISSUES  COMPACT BONE – denser, stronger type to withstand compressive forces - found under the periosteum and in the diaphysis of long bones  SPONGY BONE - contains trabeculae which forms along lines of stress to provide strength and makes bones lighter, contains red marrow (site of hematopoiesis).  BONE ANATOMY  Structure of a Long Bone 1. The diaphysis is the shaft of a long bone, and the epiphyses are distinct from the diaphysis and house the epiphyseal plate. 2. The epiphyseal plate is the site of lengthwise bone growth. 3. The medullary cavity is a space within the diaphysis. 4. Red marrow is the site of blood cell production, and yellow marrow consists of fat.  BONE ANATOMY 5. The periosteum covers the outer surface of bone. The outer layer contains blood vessels and nerves. The inner layer contains osteoblasts, osteoclasts, and osteochondral progenitor cells. Perforating fibers hold the periosteum, ligaments, and tendons in place. 6. The endosteum lines cavities inside bone and contains osteoblasts, osteoclasts, and osteochondral progenitor cells. BONE GROWTH - LENGTH  Epiphyseal plate -area of growth in a long bone  On the epiphyseal side of the epiphyseal plate, cartilage is formed.  On the diaphyseal side, cartilage is ossified, and the diaphysis grows in length.  Four zones of cell in the epiphyseal plate: 1. Reserve zone 2. Proliferative zone 3. Zone of maturation and hypertrophy 4. Zone of calcified matrix BONE GROWTH - DIAMETER  Appositional growth - growth in diameter continue even after longitudinal growth ceases  Osteoclasts resorb old bone that lines the medullary cavity  Osteoblasts, via intramembranous ossification, produce new bone tissue beneath the periosteum  Modeling - erosion of old bone along the medullary cavity and the deposition of new bone beneath the periosteum. BONE REMODELING  Remodeling - resorption of old or damaged bone takes place on the same surface where osteoblasts lay new bone to replace that which is resorbed.  Even without injury or exercise, about 5 to 10 percent of the skeleton is remodeled annually just by destroying old bone and renewing it with fresh bone. FRACTURE  Fracture - broken bone  Types of Fracture 1. Transverse -Occurs straight across the long axis of the bone 2. Oblique -Occurs at an angle that is not 90 degrees 3. Spiral -Bone segments are pulled apart as a result of a twisting motion 4. Comminuted -Several breaks result in many small pieces between two large segments FRACTURE  Types of Fracture 5. Impacted -One fragment is driven into the other, usually as a result of compression 6. Greenstick -A partial fracture in which only one side of the bone is broken 7. Open (or compound) -A fracture in which at least one end of the broken bone tears through the skin; carries a high risk of infection 8. Closed (or simple) -A fracture in which the skin remains intact BONE REPAIR SKELETAL SYSTEM  Skeletal system -all the bones, cartilages, and ligaments of the body that support and give shape to the body and body structures.  206 bones in adults  Two major divisions: 1. Axial Skeleton 2. Appendicular Skeleton