Osseous Tissue and Bone Structure

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Osseous Tissue and Bone Structure
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2010-10-03 01:46:17
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IBHS exam Dr Munson
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Osseous Tissue and Bone Structure (IBHS, Dr. Munon Exam 3 lecture 5)
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  1. Skeletal System Functions:
    • Support and Attachement for connective tissue
    • Protection of vitale orangs
    • Leverage function as levers to move loads
    • Blood Cell Production Hematopoiesis in red bone marrow
    • Mineral and Lipid Storage Body's reseves for calcium (99%) and phosphate (88%) and Storage of lipids in YELLOW bone marrow
  2. Gross Anatomy of Bones:

    Classified by Shape
    • Long:(skinny and long) Upper arm, forearm, legs, hands, feet, fingers, toes
    • Short: Carpals (wrist), tarsal (ankle)
    • Flat: Facial, skull, sterum, jaw, ribs, scapula
    • Sutural : (tiny like a grain of sand and upto a quater)- between sutures in skull
    • Irregular: Vertebrae, Pelvis
    • Sesamoid: Patella
  3. Facial, skull?
    A. Irregular
    B. Flat
    C. Sutural
    D. Short
    E. Long
    F. Sesamoid
    B. Flat
    (this multiple choice question has been scrambled)
  4. Carpals, tarsal?
    A. Sutural
    B. Flat
    C. Sesamoid
    D. Long
    E. Irregular
    F. Short
    F. Short
    (this multiple choice question has been scrambled)
  5. Hands, feet, fingers?
    A. Sutural
    B. Long
    C. Short
    D. Flat
    E. Irregular
    F. Sesamoid
    B. Long
    (this multiple choice question has been scrambled)
  6. Vertebrae?
    A. Short
    B. Sutural
    C. Long
    D. Sesamoid
    E. Flat
    F. Irregular
    F. Irregular
    (this multiple choice question has been scrambled)
  7. Bone Types:
    • Compact Bone
    • Spongy Bone
  8. Bone Types:

    Compact Bone
    • Hard, outer portion
    • 80% bone mass
    • 20% surface area
    • Parallel stress, NOT perpendicular
    • Appendicular skeleton (in appendages)
  9. Bone Types:

    Spongy Bone
    • Lighter, inner portion and bone ends
    • 20% bone mass
    • 80% surface area
    • Multidirectional stress
    • Axial skeleton (ribcage, spinal cord, etc)
  10. Spongy or Compact? 80% bone mass and 20% surface area?
    Compact
  11. Bone Coverings:

    Periosteum
    Endosteum
  12. Bone Coverings:

    Perioosteum
    Outside compact bone, except in joints
  13. Bone Coverings:

    Endosteum
    Medullary cavity and central canal
  14. Bone Cytology and Anatomy:

    CELL TYPES
    • Osteoprogenitor: Bone Stem Cell
    • Osteoblasts: Bone Builders
    • Osteocytes: Bone Maintanance
    • Osteoclasts: Bone Demolition
  15. Bone Gross Anatomy:

    Epiphysis- ends
    Diaphysis- shaft (middle)
    Metaphysis- beween/middle of Epiphysis and Diaphysis
  16. Bone Anatomy : Matrix

    Layers of matrix
    Lamellae
  17. Bone Anatomy: Matrix

    Inorganic component
    • 67% of bone weight
    • Calcium Phosphate + Calcium Hydroxide= Hydroxyapatite
    • During formation of these crystals, CaCO3, Na+, Mg++, & F- are incorporated
    • Hard & inflexible, Brittle
    • Resists to compression(will shatter when exposed to bending twisting, or suddent impacts)
  18. Bone Anatomy: Matrix

    Organic Component
    • 33% of bone weight
    • Collagen Fibers (very small amount of cells)
    • Tough BUT flexible (stronger than steel)
    • Tolerates twisting & bending
    • Scaffolding for crystal formation
  19. What is the Bone Matrix composed of?
    • INorganic component (67%)
    • Orgnaic component (33%)
    • Very Little Ground Substance
  20. Functions of the Periosteum:

    *Superficial Layer of compact bone that covers All bones(NOT within joint cavities)
    • Isolates the bone from the surrounding tissues
    • Provides a route for the circulatory and nervous supply
    • Actively participates in bone growth, remodeling and repair
    • Anchors bones to tendons & ligaments
  21. BONE CYTOLOGY:

    PERIOSTEUM (not found in joints)
    • Isolates bone from surround tissue
    • Provides route for vessels and nerves
    • Anchors bone to tendons and ligaments
    • Active in growth, repair, and remodeling


    (NOTE: osteocytes are the only ones NOT found in periosteum)
  22. Bone Cytology

    Endosteum
    • Lines marrow Cavity and Central Cannal
    • Active in growth, repair and remodeling.

    <incomplete CELLULAR layer)

    (NOTE: osteocytes are the only ones NOT found in endosteum)
  23. Bone Cell Physioogy:

    Osteoprogenitors
    • Origin: mesenchymal cells
    • Location: Cellular layer of the persiosteum, endosteum and linings of canals
    • Function: stem cells of bone, differentiate into osteoblast.
  24. Which of the following is NOT found in both the periosteum and endosteum:

    A. Osteoprogenitors
    B. Osteoblasts
    C. Osteoclasts
    D. Osteocytes
    D. Osteocytes (remember they are osteoblasts that get stuck in the MATRIX)
    (this multiple choice question has been scrambled)
  25. Bone Cell Physiology:

    Osteoblasts
    • Origin: Osteoprogenitor Cells
    • Location: Periosteum and Endosteum
    • Functions: Osteogenesis: Production of bone matrix (fibers and ground substance)
    • Process: Initially, matrix is primarily organic (collagen)- OSTEOID (aka before calcium is deposited)
    • Calcium Phosphate is then deposited (which converts Osteoid to bone)
  26. What is the organic matrix called before salts are deposited?
    Osteoid
  27. OSTEOCYTES develop from osteoblasts that have become completely surrounded by bone matrix
  28. Which of the following is very important for repairing a fracture?
    A. Osteoprogenitors
    B. Osteoblasts
    C. Osteocytes
    D. Osteoclasts
    A. Osteoprogenitors (remember: its a stem cell)
    (this multiple choice question has been scrambled)
  29. Which of bone cells elevate the concentration of calcium phosphate above its solubility limit triggering the deposit of calcium salts in the organic matrix... which converts osteoid to bone?
    Osteoblasts (remember blast-precursor aka a producer)
  30. Bone Development:

    Bone skeleton starts to form 6 weeks after fertilization
    Before this+ Cartilage
    Portions do not stop growing until ~25 years
    "Remodled" for lifetime
  31. Process of replacing tissue with bone
    Ossification
  32. 2 Types of Ossification:

    1. Endochondral Ossification : Most Bones (long bones), Bone replaces existing cartilage
    2. Intramembranous Ossification: Flat Bones, Develops from fibrous connective tissue or meschyme
  33. Calcification:The deposition of calcium-salts occurs during ossification, but it can also occur in other tissues.
  34. Fibrodysplasia Ossificans Progressive (FOP)
    Rare Genetic disease that from form normal bone in the wrong places after minor injury and provide the most dramatic demonstartions of heterotopic bone formation
  35. Supporting Connective Tissue: Cartilage
    • Matrix: Ground Substance: Chondroitin Sulfate (firm gel)
    • Fibers: Collagen, elastic reticular
    • Cells: Chondrocyte (in lacunae)
    • Avascular: Chondrocytes produce anti-angiogenic factor'
    • Reparability: limited
  36. Supporting Connective Tissue: BONE
    • Matrix: Ground Substance (2/3): Calcium phosphate and calcium carbonate
    • Fibers: (1/3) Collagen
    • Cells: Osteocytes (in lacunae)
    • Vascular: Higher energy demands than cartilage
    • Reparability: extensive
  37. Avascular? Cartilage or Bone?
    Cartilage
  38. Cartilage or Bone? Chondrocytes in lacunae
    Cartilage
  39. Cartilage or Bone? Limited Reparability
    Cartilage
  40. 3 Types of Cartilage
    • 1. Elastic Cartilage
    • 2. Hyaline Cartilage
    • 3. Fibrous Cartilage
  41. Elastic Cartilage
    • Matrix: elastic fibers
    • Resilient and flexible
    • External ear, epiglottis, larynx, auditory tube
  42. Hyaline Cartilage
    • Most common
    • Matrix: densely packed collagen fibers
    • Tough, somewhat flexible
    • Ribs to sternum , nasal septum, joints, airways
  43. Fibrous Cartilage
    • Matrix: dense, interwoven collagen, little ground substances
    • Very tough and durable
    • Resists compression, absorbs shock
    • Between vertebrae, pubic symphysis, knees

    ***in large weight baring joints
  44. Which type of cartilage is the most common?
    Hyaline cartilage
  45. 2 types of Cartilage Growth?
    Appositional and Interstitial Growth
  46. Cartilage Growth; Appositional
    • Cartilage added just benath the surface of the perichondrium
    • Stem Cells in the inner layer of perichondrium divide and differeint into immature chondroblasts
    • Secrete new cartilage matrix
    • Chondroblasts mature into chondrocytes
    • mostly occurs in utero
  47. Cartilage Growth- Interstitial
    • Condrocytes in matrix divide
    • New matrix secreted
    • In utero development thorugh adolescnece
  48. Endochondral Ossification

    As we age we have a 2nd round of ossification occurs at epiphyses by osteoblast

    FYI: Ends of phalanges dont finish process until early adulthood
    • More remodeling by osteoclast
    • Epiphysis fill with spongy bone
    • Cartilage growth oupaces bone growth until puberty
    • Cartilage remains at ends (articular) and prevents bone to bone damage
  49. How do bones get longer?
    • Continued cartilage growth at the epiphyseal plate (growth plate)
    • cartilage keeps expanding and keeps being converted to bone
  50. How do bones get thicker?
    • Bone diameter increases via appositional growth
    • Cell of inner layer of periosteum differentiate into osteoblasts and deposit bone matrix
  51. Endochondral Ossification:


    Puberty
    • Rapid bone growth via:
    • Sex Hormones
    • Growth Hormones
    • Thyroid Hormones
    • Result is that osteoblasts outpace cartilage growth and epihphyseal cartilage diminshes
  52. In childhood cartilage growth rate is equal to bone deposition rate

    But as you age the bone desposition rate is greater than cartillage growth rate
  53. Intramembranous Ossification (formation of flat bones)

    Bones are fomred in the deep dermis (aka dermal ossification)

    *** cartilage IS NOT the template
    • 1. Messenchymal cells cluster and secret organic matrix
    • osteoid becomes mineralized via alkaline phosphatase
    • Mesenchymal cells --> osteoblasts--> osteocytes (due to calcification)
    • Ossification center spreads outward into spicules
    • Blood Vessels invade
    • Osteoblasts become trapped in matrix--> osteocytes
    • 2. Spicules interconnect, trapping blood vessels
    • 3. Remodelling resuling in periostum and medullary cavities.
  54. Structure of Compact Bone

    Concentric Lamallae
    • Osteocytes in lacunae arranged in concentric layers of matrix (lamellae) around a central (Haversian) canal
    • Osteon=central canal + concentric llamallae
    • Perforating Canals (Canals of Volkmann) connect osteons
  55. Structure of Compact Bone

    Interstitial Lamallae
    • Between Osteons no central canals
    • Osteocytes in lacunae
  56. Circumferential Lamallae
    • Outer and Inner Surfaces: covered by periosteum or endosteum
    • Osteocytes in lacunae
    • No central Canals
  57. Structure of Spongy Bone
    • Lamellae aren't arranged as osteons instead arraned as TRABECULAE (struts)
    • Osteocytes in lacunae in the lamallae
    • No capillaries in matrix
    • Nutrients/waste diffuse via canaliculi
  58. Structure of Spongy Bone:

    Bone Marrow (between the trabeculae)
    • Red (epihpyses and flat bones)- Hematopoiesis (RBC, WBC, platelets)
    • All our bone marrow is RED at Birth
    • As adults about 50% Red and 50% Yellow
    • Yellow (medullary cavity of long bones)
    • Adipose tissue
    • Lipid and fat storage
    • None at birth
    • adults About 50%
  59. Bone Remodeling
    • Remodeling occurs for lifetime
    • Renewal of organic and inorganic componeents
    • High Turnover rate:
    • Young adults: 20% of the skeleton is "turned over" each year
    • Not all parts of the bone affected equally
    • Spongy bone replaced in femur- 2-3X/year
    • Compact bone of femur unchanged

    All Cell types are involved
  60. Which cell is involved in maintaining bone?
    Osteocytes
  61. Which cell of the bone is involved in recycling?
    Osteoclasts
  62. Which of bone cells are involved in deposting?
    Osteoblasts
  63. Bone Remodeling:

    Remodeling Varies

    Age of the Individual
    • Childhood: deposition faster than resorption
    • Maturity: deposition and resorption balanced
    • Aging: resorpton outpaces deposition
  64. Bone Remodeling:

    Remodeling Varies

    Physical Activity and Exercise
    • Stressed bones become thicker and stronger
    • Stonger attachement sites for tendons
  65. Bone Remodeling:

    Remodeling Varies

    Circulating Hormone Levels
    • Altering the rate of deposition (ESTROGEN) and resorption
    • Endocrine disorders often affect the skeletal system
  66. Bone Remodeling:

    Remodeling Varies

    Rate of Calcium and Phosphate Absorption/ Excretion
    • For bone mass to remain constant, this must be balanced
    • Renal problems can impact skeletal system
  67. Bone Remodeling:

    Remodeling Varies
    • Age of the Individual
    • Physical Activity and Exercise
    • Circulating Hormone Levels
    • Rate of Calcium and Phosphate Absorption/Excretion
    • Genetic mutation or environmental factors
  68. Metabolic Bone Disorders

    Osteomalacia:
    Softening of the bones due to a lack of or inability to utilize vitamin D/ Cholcalciferol

    Rickets: osteomalacia in children (breastfed baby are more likely to get it)
  69. Metabolic Bone Disorders:

    Osteopenia:
    Mild reduction in bone density

    • begins in 30-40s
    • Osteoblasts slow down, osteoclasts do not
    • Women lose 8% per decade, Men lose 3% per decade
    • May progress osteoporosis
  70. Osteoporosis: Severe reduction in bone denisity: effects function

    ***Most common Metabolic Bone Disorder***
    • Literally means "Porous Bone"
    • Normal Mineralization but bone density decreased
    • Loss can be generalized or localized
    • ~10 million Americans (majority women) &34 mil more at risk
    • Annual Costs: ~$17 bil/year
  71. Osteoporosis:

    Pathophysiology
    • Bone resorption outpaces bone depositon
    • Loss of bone density: possible poor quality of "new" bone
    • Leads to bone fragility---> risk of pathologic fracture
  72. Osteoporosis Risk Factors

    Non-Modifiable
    • Gender (females)
    • Race and Genetics: Asians/Caucasions> Hispanics> African Americans
    • Family History
    • Advancing Ages
    • Post-Menopausal
    • Small Frame
  73. Osteoporosis Risk Factor

    Modifiable
    • Inadequate Diet (plenty of Calcium)
    • Alcohol, smoking, caffieine
    • Inadequate physical activity
    • Meds (glucocorticoids, Warfarin, H+ pump inhibitors)
  74. Osteroporosis Basic Types
    • Type 1 (post-menopausal)- Low Hormone Levels, 50-70 yrs (women 3-6X) Bone affected are the Spongy> Compact
    • Type 2 (age-related)- Age, 70+years (women 2X) Bone affected spongy= compact
    • Type 3 (secondary)- Medications, Disease States are causes. Incidence and Bone Affected are variable.
  75. Osteoporosis Treatment:
    • Greater Calcium/Vit D in Diet or Enviroment
    • More Calcium and Vit D fortified foods,
    • Vitamins
    • More Sunlight exposure
    • Exercise Weight bearing exercise, lowers risk of hip fractures -30%
    • Reduce or Eliminate Modifiable Risk Factors- Alcohol, Caffeine, and smoking
    • Hormone Replacement Therapy

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