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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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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!
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)
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
Bone Classification: Shapes Sternum, scapula, ribs Clavicle, patella Femur, Phalanges & metacarpals Tarsals Figure 6-1
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)
An Overview of the Skeleton • Skeletons differ in shape based on what? • Why is looking at bones important/useful?
An Overview of the Skeleton • How are male & female skeletons different? • Skull: • Frontal bone • Cranium • Mandible • Pelvis: • Pelvic outlet • Pubic angle
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)
Bone Tissue Two types: Compact & Spongy Compact Bone • Layers of compact cover all bone surfaces, except at joints • Found where stresses occur
Bone Tissue Spongy Bone • Network of bony rods (trabeculae) • Found in center & in epiphysis • Lighter to decrease wt of skeleton • Spaces filled with marrow
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
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!
Bone Growth Figure 6-6
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
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%)
Disorders in Bone Growth & Remodeling • Osteomalacia (Rickets) = Soft Bones from lack of Vit.D causes low Ca
Disorders in Bone Growth & Remodeling • Osteogenesis Imperfecta = Genetic disorder affecting collagen fiber formation (1 in 20,000)
Disorders in Bone Growth & Remodeling • Achondroplasia (Dwarfism) = Genetic disorder affecting cartilage formation mainly at epiphyses
Disorders in Bone Growth & Remodeling • Acromegaly (Giantism) = Excess growth hormone - most often after epiphyseal plates closed
Disorders in Bone Growth & Remodeling • Marfan’s Syndrome = Defective CT - excess cartilage at epiphyseal plates
The Axial Division: The Skull Figure 6-10
The Axial Division: The Skull Figure 6-11(a)
The Axial Division: The Skull Figure 6-11(b)