Skeletal Tissue & System Bone “osteo”

Divisions of Skeletal System How many can you name?

Cancellous (Spongy) Bone Bone Cells Bone Marrow Calcium Regulation Types of bones Parts of long bones Bone Tissue Bone Matrix Inorganic Salts Osteoporosis Organic Matrix Compact Bone Cancellous (Spongy) Bone Bone Cells Bone Marrow Calcium Regulation Bone Development The Skeleton The Skull The Vertebral Column

A. Functions of Bone Support shape, alignment & body position supports soft tissues Protection Skull-brain, ribs-heart & lungs Movement Muscles & tendons are anchored to bones which act as levers Ligaments hold bone to bone Mineral Storage & Homeostasis Reservoir for calcium, phosphorus and other minerals Calcium moves into or out of bones to keep blood levels steady Fat Storage Hematopoiesis Blood cell formation, occurs primarily in red marrow 1st x-ray ever – 1986 Roentgen's wife’s hand 1st Nobel Prize in Physics

B. Types of bones 1. Long Bones 2. Short Bones 3. Flat Bones Long axis with unique shaped articular ends ex: femur (thigh), humerus (arm) 2. Short Bones Cube or box shaped ex: wrist(carpals) or ankle(tarsals) bones 3. Flat Bones Broad and thin with often curved surfaces Surface for muscle attachment Red marrow is found in some flat bone like the sternum ex: shoulder blades(scapula), breatbone(sternum) and ribs 4. Irregular Bones Come in clusters and come in various shapes and sizes Sesamoid bones are irregular bones that are found alone, kneecap(patella)- lot of stress ex: vertebral bones, facial bones

Long Bones Flat Bones Irregular Bones Short Bones

C. Parts of a long bone 1. Diaphysis Main shaft portion of bone Cylindrical and hollow Very strong yet light 2. Epiphyses Bulbous shape at end of bones Site of muscle attachments Made of spongy, cancellous tissue filled with red marrow 3. Epiphyseal plate/line layer of cartilage seen in early development (age determination) separates epiphyses from Diaphysis. In mature bone is referred to as the metaphysis 4. Articular Cartilage Thin layer of hyaline cartilage that covers epiphysis Cushions jolts and blows

Parts of a long bone 5. Periosteum 6. Medullary (marrow) cavity Dense white fibrous tissue, covers bone and joint surfaces Periosteum fibers penetrate underlying bone Muscle tendon fibers interlace with periosteum fibers anchoring them into place Contains bone forming and destroying cells (osteoblasts & osteoclasts) Contains blood vessels that aid in bone formation and repair of bone 6. Medullary (marrow) cavity Hollow space of diaphysis Filled with fatty yellow marrow 7. Endosteum Thin membrane that lines medullary cavity

D. Bone (osseous) Tissue Made of cells, fibers and extracellular fluid = connective tissue Extracellular material predominates and is hard and calcified Contains collagen fiber(proteins) =stength/flexibility Tensile strength equal to iron with 1/3 the weight. Structure = function allows bone to carry out its supportive and protective function Collagen Fibers

Bone Matrix A) Inorganic Salts Hydroxyapatite (HAP)- specialized crystals of calcium and phosphate Hardness of bone & enamel on teeth Other minerals found in bone are magnesium, sodium, sulfate, and fluoride.

Osteoporosis Disease Age related disease which results on loss of bone mineral density Causes bone fragility and susceptibility to fractures White women during the first 10 years of menopause are most susceptible Treatment hormone replacement therapy(HRT) Non-hormonal drugs, Fosamax Calcium supplements Weight bearing exercise healthy osteoporosis

Bone Matrix B) Organic Matrix collagen fibers and ground substance Gel like substance Made of protein and polysaccharides Provides support and adhesion Aids in growth, repair, and remodeling Adds to overall strength and resistance of bone As the marrow tissue invades the cell columns, spicules of cartilage will be left. The cartilage matrix is calcified (purple), and one small area of bone deposition, has begun on it (the red color at the upper right). The small cells caught in the red matrix are osteocytes.

Compact Bone Osteons AKA: Haversian systems functional units of compact bone Main function is to provide nutrients and remove wastes from osteocytes that are “trapped” in the bone

Compact Bone 4 Main components Lamelle- concentric cylindrical layers of calcified matrix Lacunae- “little lake”small spaces where cells are imprisoned Canaliculi- small canals radiated from lacunae that connect cells to larger canal Haversian canals- lengthwise canals that contain blood and lymph vessels, and nerves. Volkmanns Canals- horizontal canals that connect Haversian canals

Cancellous (Spongy) Bone Made of needle like spicules call trabeculae Lack Haversian systems but do contain canaliculi for nutrient & waste removal Trabeculae are oriented along stress lines to enhance bones strength Stores red marrow Found in between flat bones and epiphysis of long bones

Major Bones of the Skull

Hyoid Bone Single U shaped bone just above the larynx Tongue muscles attached Only bone to articulate on its own. Part of the axial skeleton

The Spine

Bone Cells h Osteoblasts Osteoclasts Osteocytes Osteoclasts Osteocyte Bone building cells Secrete ground substance Allows for deposition of Ca and phosphate Osteoclasts Bone destroyer cells Giant multinucleated cells Contain large number of lysosomes Osteocytes Mature bone cells Are walled into lacunae in matrix Osteoclasts Osteocyte

Bone Marrow Also called myeloid tissue Found in medullary cavities of long bones and spaces of spongy bone Red Marrow Makes up almost all marrow in infants Produces red blood cells Gradually changes to yellow marrow Found in ribs, pelvis, sternum, humerus & femur Yellow marrow Made up of adipose tissue During time of low blood level it can convert back to red marrow

Regulation of Blood Calcium levels Functions of Ca Bone formation Nerve impulse transmission Skeletal and Cardiac muscle contraction Parathyroid hormones When blood Ca is LOW the parathyroid will release PTH PTH is the most critical factor in Ca homeostasis This stimulates osteoclasts to breakdown bone Increases renal absorption of Ca Increases synthesis if Vitamin D with increase Ca absorption When blood Ca is HIGH osteoclast activity is suppressed The thyroid will release Calcitonin Calcitonin stimulates osteoblast activity, depositing Ca

Bone Development- Ossification Osteogenisis- process in which cartilage is converted into hard bone by the work of osteoblasts and osteoclasts *Fontanels- soft spot in infants, remain until bones in skull fuse.

Bone Development- Ossification Intramembranous Ossification when connective tissue in replaced by bone Spongy bone is created first and then covered by compact bone Results in Appositional growth, bone growth on the outer surface(wider/bigger) https://www.youtube.com/watch?v=xXgZap0AvL0&list=PL4HNUeJFBKN2_mdG6dvGIYVtcj6vtCfJJ&index=5

Bone Development- Ossification Endochondrial Ossification Progresses from diaphysis to epiphysis Increases bone length Epiphyseal plate remains as cartilage until one growth is complete Young children and pre teens are susceptible to epiphyseal fractures

Rickets Vitamin D is essential to bone calcification If children are deficient in Vitamin D their epiphyseal plate with length but fail to calcify The bone bends and deforms under weight-bearing

Fractures and Breaks

Fractures and Breaks

Male vs. Female Skeleton