Chapter 7 Skeletal System

1. Chapter 7 Skeletal System

2. Functions of Skeletal System:1. Support 2. Protection3. Produces blood cells4. Stores inorganic materials

3. Classification – bones classified by shape: • 1. Long • 2. Short • 3. Flat • 4. Irregular • 5. Sesamoid

4. Structure of Long Bone Epiphysis- expanded portion at end, forms joint. Epiphyseal disk (line)-growth plate Diaphysis- shaft of bone Medullary cavity-hollow chamber in center Spongy bone- cancellous bone, found mainly in epiphysis Compact bone-tightly packed tissue Periosteum-tough, vascular covering Endosteum- membrane of bone forming cells Articular cartilage-layer of hyaline cartilage on epiphysis of bone

5. Structure of a Long Bone • Red marrow- formation of red blood cells, white blood cells and platelets. • Found in flat bones and epiphysis • Yellow marrow- stores fats, no blood cell production. • Found in diaphysis

6. Compact vs. Spongy Bone • Perforating(Volkmann’s) canal- Connects central canals • Trabeculae-bony plates of spongy bone • Canaliculi- canals btwn osteocytes • Osteocyte-Bone cells • Lacunae- space in bone containing osteocytes

7. Compact vs. Spongy Bone

8. Bone Structure Animation • structure of bone animation

9. Osteoblast vs. Osteoclast • Osteoblast- bone forming cells which deposit Calcium and Phosphorous into the dense collagen framework. • Osteoclast- Large multinucleated cells formed from fusing white blood cells. • Secrete an acid which breaks down the bony matrix • Both work together over a person’s lifetime to remodel bone and allow for resorption on minerals.

10. Osteoblast vs osteoclast • osteoblast osteoclast animation

11. Homeostasis of Bone Tissue

12. Bone Development – 2 Types: 1. Intramembranous ossification (changing cartilage to bone) (ex. - skull) • layers of undifferentiated connective tissue appear at sites of future bone • connective tissue cells differentiate into osteoblasts (cells that build bone) around blood vessels • osteoblasts become osteocytes (mature bone cells) when completely surrounded by a bony matrix • Connective tissue on surface forms the periosteum

13. Intramembranous Ossification

14. Intramembranous Ossifiction

15. 2. Endochondral ossification (remainder of skeleton) • Hyaline cartilage models form at sites of future bone • Cartilage cells degenerate over time • osteoblasts form bone over cartilage • osteoblasts become osteocytes when completely surrounded by a bony matrix

16. Ossification Animation • Ossification animation

17. Endochondral Ossification

18. Bone Development • In a long bone, hyaline cartilage is replaced by bony tissue in the center of the diaphysis first (primary ossification center) • Bone develops from this point towards the end of the bone • Secondary ossification centers appear in the epiphysis last.

19. Bone Development

20. Growth of Bones • Epiphyseal disk – area of growth; separates epiphysis from diaphysis; 4 layers: 1. Resting cells – closest to end; do not add length but act as anchor 2. Reproducing cells - as they reproduce, they lengthen the bone 1.

21. Growth of Bones 3. Mature cells – growing and accumulating Ca 4. Degenerating cells & osteoblasts depositing bony tissue

22. Epiphyseal Plate Video • http://www.youtube.com/watch?v=RTx-Z0a9wvM

23. Epiphyseal disk • Bones continue to lengthen until epi. disks are ossified (approx. 21 yrs. of age) • Bones thicken through- out life as compact bone is added under peri- osteum • Hyaline cartilage on ends remains

24. Bone Growth Video • http://app.discoveryeducation.com/player/view/assetGuid/39B53919-B11C-4D2C-A92C-E030DF639351

25. Epiphyseal disk 1. Radial growth plate→ 2. Fracture – distal end of radius → Digital growth plate (in fingers) (2 ½ yr. old)→

26. Fractures • Greenstick- incomplete break in convex surface • Fissured- incomplete longitudinal break • Comminuted-complete, fragments bone • Transverse- complete break at right angle • Oblique- complete at angle other than right angle • Spiral- complete, caused by twisting of bone

27. Fracture Repair • 4 stages • Blood escapes from blood vessels and from hematoma. • Spongy bone forms near blood vessels, fibrocartilage forms in distant regions (within days to weeks) • Bony callus forms from cartilaginous callus similar to bone formation • Osteoclasts remove excess bone to restore to original

28. Bone Fracture Video • https://www.youtube.com/watch?v=MNkI6Of2PRs

29. Factors Affecting Bone Growth(Nutrients)

30. Rickets/Osteomalacia

31. Factors Affecting Bone Growth(Hormones) Deficiency Effect Pituitary growth Pituitary dwarfism hormone (excess – pituitary (stimulates cell division gigantism/acro- in the epi. disks) megaly) Thyroid hormone premature disk (stimulates cartilage ossification-growth replacement in disk) stunt ed

32. Pituitary dwarfism

33. Acromegaly Yao Defen is 34 yrs. old & The world’s tallest female at 7ft. 8 in!!

34. Factors Affecting Bone Growth(Hormones & Exercise) Deficiency Effect Sex hormones stimulate ossifi- (cause growth of cation of disks; long bones; estrogen stop bone length stronger than androgen) Physical stress bone thins & weak- (stimulates bone width; ens; atrophy hypertrophy)

35. 2 divisions of skeleton: • Axial – skull, vertebrae, sternum, ribs (thorax), hyoid bone • Appendicular – pectoral & pelvic girdles, upper & lower limbs Human Skeleton – composed of 206 bones (extra – sutural)

36. Axial vs. Appendicular Skeleton

37. Surface Markings on Bone • Surface of bones have various structural features for specific functions • Depressions & Openings: Foramen Meatus Sinus

38. Foramen Opening for b.v., nerves, ligaments (ex.-foramen magnum)

39. Meatus Tubelike passageway (ex.-external auditory meatus)

40. Sinus Cavity within a bone (ex.-frontal sinus)

41. Surface Markings on Bone • Processes that Form Joints: Condyle Head Facet

42. Condyle Rounded process for articulation w/another bone (ex. – mandibular condyle)

43. Head An enlargement at the end of a bone (ex.-head of femur)

44. Facet Small, nearly flat surface where 2 bones articulate (ex.-vertebral facet)

45. Surface Markings on Bone • Processes that Connective Tissue Attaches To: Tuberosity Spine Trochanter Crest Process

46. Tuberosity Knoblike process (ex.-ischial tuberosity)

47. Spine Thornlike ridge or projection (ex.-spine of scapula)

48. Trochanter Large process or projection (ex.-trochanter of femur)

49. Crest Ridgelike projection (ex.-iliac crest)

50. Process Prominent projection on a bone (ex.-spinous process)