1. Bones & Skeletal Tissue
Ch 6

2. Function of the Skeletal System
Support
Protection
Movement
Mineral storage
Blood cell formation (hemopoiesis)
Triglyceride storage

3. Bones & Cartilage

4. Anatomy of a Long Bone spongy bone Proximal compact bone epiphysis
Endosteum
diaphysis
epiphyseal line
yellow marrow
Sharpey’s fibers
Distal
epiphysis
periosteum
hyaline cartilage

5. Anatomy of a Bone Haversian system spongy bone periosteum Lamellae
osteocyte
Haversian system
Lamellae
spongy
bone
periosteum

6. Haversian System in Compact Bone
osteocytes in lacunae
central canal

7. Haversian System in Compact Bone
osteocytes in lacunae

8. Intramembranous Ossification
Cranial bones
Mandible
Clavicles
frontal, parietal, occipital, and temporal bones)

9. Intramembranous Ossification

10. Fetal Skeleton
275 bones 16 weeks fetus

11. Fig

12. bone calcified cartilage epiphyseal line epiphyseal plate
Fetus: 1st 2 months
Endochondral Ossification
1o ossification center
2o ossification center
bone
Hyaline cartilage
calcified cartilage
Just before birth
Bone growth stops around age 21 for males and 18 for females when the epiphysis & diaphysis fuse (epiphyseal plate closure)
epiphyseal line
epiphyseal plate
Childhood
Adult

13. Epiphyseal Plate

14. During puberty- sex hormones: estrogen and testosterone
Hormonal Regulation
of Bone Growth
GH from anterior pituitary, which is regulated by T3 and T4 of the thyroid
During puberty- sex hormones: estrogen and testosterone

15. Hormones
TSH GH
TSH T3 T4

16. Hormones
Ovary
Testes
Estrogen
Testosterone

17. Hypersecretion of GH- gigantism
Sultan Kosen (R)
8 ft 1 in
Hyposecretion of GH- dwarfism
He Pingping
2 ft 5.37 in

18. Maintains homeostasis
Bone Homeostasis:
Remodel & Repair
Parathyroid hormone- stimulates osteoclasts
Calcitonin- inhibits osteoclasts
Maintains homeostasis

19. Bone Homeostasis:
Remodel & Repair

20. Bone cells that aid in remodeling
Osteoblast
Builds new bone
Osteocyte
Mature bone cell
Osteoclast
Eats bone
OsteoblastsOsteoblasts are responsible for building new bone and lie at the centre of bone physiology. Their functions include the synthesis of collagen and the control of mineralisation.
OsteoclastsOsteoclasts are specialised cells that resorb bone. They work by sealing off an area of bone surface then, when activated, they pump out hydrogen ions to produce a very acid environment, which dissolves the hydroxyapatite.
OsteocytesBone adapts to applied forces by growing stronger in order to withstand them; it is known that exercise can help to improve bone strength. Osteocytes are thought to be part of the cellular feed-back mechanism which directs bone to form in the places where it is most needed. They lie within mineralised bone and it is thought that they may detect mechanical deformation and mediate the response of the osteoblasts.

21. Repair of Fractures
hematoma
callus
bony callus
bone
remodeling

22. Common Types of Fractures
Usually treated by realignment
Simple- closed fracture (8-12 wks to heal) bone breaks cleanly; no penetration
Compound- bone penetrates through skin
Comminuted- bone fragments into many pieces; aged or brittle bones
Compression- bone is crushed
Depressed- broken bone portion is depressed inward
Impacted- broken bone ends are forced into each other
Spiral- excessive twisting of bone
Greenstick- bone breaks incompletely

23. Common Types of Fractures
Oblique
Comminuted
Spiral
Compound

24. Bone Repair Electrical stimulation of the fracture site:
Increases speed and completeness of healing
The e- stimulation inhibits PTH and slow osteoclasts down from reabsorbing bone
2. Ultrasound treatment:
Daily treatments reduce healing time of broken bones by 25-35%
3. Free vascular fibular graft technique:
Transplant fibula in arm
Gives good blood supply not available in other treatments
4. Bone substitutes:
Crushed bone from cadaver- but risk of HIV and hepatitis
Sea bone- coral
Artificial bone- ceramic

25. Diseases of the Skeletal System
Osteoporosis- bone reabsorption outpaces bone deposit; bones become lighter and fracture easier
Factors:
age, gender (more in women)
estrogen and testosterone decrease
insufficient exercise (or too much)
diet poor in Ca++ and protein
abnormal vitamin D receptors
smoking

26. Osteoporosis 29 40 84 92

27. Osteoporosis

28. Diseases of the Skeletal System
Rickets- vitamin D deficiency
Osteomalacia- soft bones, inadequate mineralization in bones, lack of vitamin D

29. Diseases of the Skeletal System
Rheumatoid arthritis- autoimmune reaction

30. What does the secondary site of ossification produce?
INQUIRY
What does the secondary site of ossification produce?
What is an epiphyseal line?
Provide an example of a flat bone?
How does PTH effect bone development?
How many bones in the adult skeleton?
What does an osteoblast do and where are they primarily found?