Skeletal%20Tissue%20

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Skeletal Tissue System

• Bone osteo

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1. Types of bones
2. Parts of long bones
3. Bone Tissue
4. Bone Matrix
5. Inorganic Salts
6. Osteoporosis
7. Organic Matrix
8. Compact Bone
9. Cancellous (Spongy) Bone
10. Bone Cells
11. Bone Marrow
12. Calcium Regulation
13. Bone Development
14. The Skeleton
15. The Skull
16. The Vertebral Column

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Functions of Bone

• Support
• Contribute to shape, alignment and position of
  body
• Protection
• Skull-brain, ribs-heart, lungs
• Movement
• Muscles are anchored to bones which act as levers
• Mineral Storage
• Reservoir for calcium, phosphorus and other
  minerals
• Calcium moves into or out of bones to keep blood
  levels steady
• Hematopoiesis
• Blood cell formation, occurs primarily in red
  marrow

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Types of bones

• Long Bones
• Long axis with unique shaped articular ends
• ex femur (thigh), humerus (arm)
• Short Bones
• Cube or box shaped
• ex wrist(carpals) or ankle(tarsals) bones
• Flat Bones
• Broad and thin with often curved surfaces
• Red marrow is found in some flat bone like the
  sternum
• ex shoulder blades(scapula), breatbone(sternum)
  and ribs
• Irregular Bones
• Come in clusters and come in various shapes and
  sizes
• Sesamoid bones are irregular bones that are found
  alone, kneecap(patella)
• ex vertebral bones, facial bones

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Long Bones
Flat Bones
Irregular Bones
Short Bones
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Parts of a long bone

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

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Parts of a long bone

• Periosteum
• Dense white fibrous tissue, covers bone and joint
  surfaces
• Periosteum fibers penetrate underlying bone
• Muscle tendon fibers interlace with periosteal
  fibers anchoring them into place
• Contains bone forming and destroying cells
• Contains blood vessels that aid in born formation
  and repair of bone
• Medullary (marrow) cavity
• Hollow space of diaphysis
• Filled with fatty yellow marrow
• Endosteum
• Thin membrane that lines medullary cavity

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Bone (osseous) Tissue

• Made of cells, fibers and extracellular fluid
• Extracellular material predominates and is hard
  and calcified
• Contains many collagen fibers
• Tensile strength equal to iron with 1/3 the
  weight.
• Structure allows bone to carry out its supportive
  and protective function

Collagen Fibers
Cross section of rib
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Bone Matrix

• Inorganic Salts
• Hydroxyapatite- specialized crystals of Calcium
  and phosphate
• Hardness of bone results from the deposition of
  hydroxyapatite
• Other minerals found in bone are magnesium,
  sodium, sulfate, and fluoride.

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Osteoporosis

• 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
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Bone Matrix

• Organic Matrix
• Composite of collagenous fibers and ground
  substance
• 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.
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Compact Bone

• Haverisan systems or Osteons
• functional units of compact bone
• Main function is to provide nutrients and remove
  wastes from osteocytes that are trapped in the
  Bone

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Compact Bone

• 4 Main components
• Lamelle- concentric cylindrical layers of
  calcified matrix
• Lacunae- little lakesmall 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

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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 ephiysis of long
  bones

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Divisions of Skeletal System
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Major Bones of the Skull
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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

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The Spine
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Bone Cells

• Osteoblasts
• 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
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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

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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

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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.

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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)

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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

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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

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Fractures and Breaks
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Fractures and Breaks
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Male vs. Female Skeleton