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The Skeletal System

The Skeletal System. FYE: Your Bones….  Bones aren ’ t just pieces of your skeleton.  They are a connective tissue impregnated with minerals!.  Bones aren ’ t dead!.  They have cells, bloody supply & nerves (feelings!).  Bones are strong!.

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The Skeletal System

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  1. The Skeletal System

  2. FYE: Your Bones…  Bones aren’t just pieces of your skeleton  They are a connective tissue impregnated with minerals!  Bones aren’t dead!  They have cells, bloody supply & nerves (feelings!)  Bones are strong!  Standing still the force on hip = 3x bodyweight (muscle pull) & a running man exerts a dead wt force of ~590 lbs!

  3. The Skeletal System Parts of the skeletal system Some Vocab… • BONE = Osseous Tissue • Osteology = Study of bones • Arthrology = Study of joints • Kinesiology = Study of movement • Bones • Ligaments (connect bone to bone) • Cartilage • Tendons (connect muscle to bone)

  4. Functions of the Skeletal System • Support • For wt of entire body • Framework for muscle attachment • Protects internal organs • Storage • Calcium & Phosphate • Fat cells (in yellow marrow!) • Produces blood= Hematopoiesis • Red marrow makes cells  3 million new each second! • Found in: pelvis, ribs, clavicle, vertebra, skull, ends of long bones

  5. Bone Classification: Shapes Sternum, scapula, ribs Clavicle, patella Femur, Phalanges & metacarpals Tarsals Figure 6-1

  6. An Overview of the Skeleton

  7. An Overview of the Skeleton • Axial Division • Forms center axis for everything to attach to • Includes: 80 bones • Ribs, Sternum, Vertebra (including sacrum) & Skull (including the hyoid) • Appendicular Division • Includes: 126 bones • Upper & lower extremities, Pelvis & Shoulder (clavicles & scapula)

  8. An Overview of the Skeleton • Skeletons differ in shape based on what? • Why is looking at bones important/useful?

  9. An Overview of the Skeleton • How are male & female skeletons different? • Skull: • Frontal bone • Cranium • Mandible • Pelvis: • Pelvic outlet • Pubic angle

  10. An Overview of the Skeleton • The Vertebral Column Cervical: (7) • C1 = Atlas – holds head up attaches to skull (nod) • C2 = Axis – pivots (no) • C7 = Vertebral prominens – prominent landmark Thoracic: (12) • Each joins with a rib Lumbar: (5) • Holds wt of body, takes most stress = biggest! Sacrum: (1) (5 fused together) • Supports & strengthens pelvis/hips Coccyx: (1) (4 fused together)

  11. Bone Anatomy

  12. Bone Tissue Two types: Compact & Spongy Compact Bone • Layers of compact cover all bone surfaces, except at joints • Found where stresses occur

  13. Bone Tissue Spongy Bone • Network of bony rods (trabeculae) • Found in center & in epiphysis • Lighter to decrease wt of skeleton • Spaces filled with marrow

  14. BONE CELLS 1. Osteocytes • Mature bone cells in compact bone 2. Osteoblasts  • Cells that make new bone (osteogenesis) 3. Osteoclasts  • Bone eaters - secrete acid that dissolves matrix (osteolysis) to release stored minerals  = Found in Endosteum & Periosteum

  15. Bone Formation and Growth • Begins ~6wks after fertilization - embryo is ~12mm long • Continues until 18-25 yrs • Epiphyseal Plates(discs) in ends of long bone become solid lines when done growing!

  16. Bone Growth Figure 6-6

  17. Bone Remodeling/Homeostasis • Remodeling- Continuous breakdown and reforming of bone tissue - 18% turned over/year FYE: your oldest bones are ~7 yrs! • enables skeleton to adapt to new stresses FYE: Cast on leg for 6 wks - leg loses 1/3 bone mass! • inactivity = degeneration • needed for Ca regulation - bones store 2-4 lbs • Osteoclasts break down worn-out bone cells & put • Ca in blood as needed FYE: Continues until late 40’s then bone start to get old too! • Osteoblasts pull Ca out of blood & build new

  18. Disorders in Bone Growth & Remodeling • Osteoporosis = bone mass reduced, can happen at any age • inactivity • low Ca • age (males - lose 3%/decade starting in 30’s, females lose 8%)

  19. Disorders in Bone Growth & Remodeling • Osteomalacia (Rickets) = Soft Bones from lack of Vit.D causes low Ca

  20. Disorders in Bone Growth & Remodeling • Osteogenesis Imperfecta = Genetic disorder affecting collagen fiber formation (1 in 20,000)

  21. Disorders in Bone Growth & Remodeling • Achondroplasia (Dwarfism) = Genetic disorder affecting cartilage formation mainly at epiphyses

  22. Disorders in Bone Growth & Remodeling • Acromegaly (Giantism) = Excess growth hormone - most often after epiphyseal plates closed

  23. Disorders in Bone Growth & Remodeling • Marfan’s Syndrome = Defective CT - excess cartilage at epiphyseal plates

  24. The Axial Division: The Skull Figure 6-10

  25. The Axial Division: The Skull Figure 6-11(a)

  26. The Axial Division: The Skull Figure 6-11(b)

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