1. Musculoskeletal System
Bones

2. Objectives 1) State 6 basic functions of the skeleton
2) State the gross structure of the axial and appendicular skeleton
3) Describe the basic structure of mature bone matrix
4) State the function of chondroblasts, fibroblasts, osteoblasts, osteocytes and osteoclasts
5) Describe the structure and location of cancellous and compact bone

3. Objectives 6) Describe the 3 patterns of bone ossification
7) Describe the typical stages of long bone development
8) List and state the function of nutrition, vitamins, minerals and hormones in bone growth
9) Describe the role of vitamin D, parathyroid hormone and calcitonin in calcium regulation and homeostasis
10) Identify the location of the main bones of the human body

4. Basic functions of the skeleton
Support
Framework, supports soft tissue, point of attachment for muscles
2) Protection
For internal organs e.g. brain, lungs, heart etc

5. Basic functions of the skeleton
3) Facilitates movement
Skeletal muscle contraction causes movement at movable joints
4) Storage of minerals
Ca and P stored and released when needed

6. Basic functions of the skeleton
5) Blood cell formation
Red bone marrow in certain bones produces blood cells
6) Storage of energy
Lipids stored in yellow bone marrow

7. Skeleton Axial skeleton: skull, vertebral column, ribs, sternum
Appendicular skeleton:
scapulae,
clavicles,
hip bones
limb bones

8. Types of Bones Flat (e.g. skull) Irregular Short Long
Bones are either:
Flat (e.g. skull)
Irregular
(e.g. vertebrae)
Short
(e.g. carpals)
Long
(e.g. phalanges)

9. Basic structure of Bone Matrix
65% Calcium and Phosphate salts
Inorganic  weight bearing strength
33% Collagen
Organic material, rope like and strong  strong flexible framework
(Loss of collagen  bones become ‘brittle’)
2% cells

10. Typical Long Bone

11. Bone Cells Osteoblasts: bone building cells, produce bone matrix
Osteocytes: osteoblast surrounded by matrix (i.e. mature bone cells)
Osteoclasts: bone consuming cells, remove/shape bone
Chondroblasts: cells that work on cartilage to form bone
Fibroblasts: cells that form collagen

12. Cancellous / Trabecular bone
Light, sponge like
Strong due to trabeculae
Spaces contain red or (Compact bone)
yellow bone marrow
Cancellous bone
Found: centre of flat bones,
ends of long bones

13. Trabecular / Cancellous bone
Section through the head of the femur, showing the outer layer of compact bone and the soft centre of trabecular bone, filled with red bone marrow

14. Compact Bone More dense, fewer spaces than cancellous bone
Blood vessels and nerves within Haversian canals
Circumferential lamellae is very strong  protection

15. Compact Bone

16. Bone Ossification Bone ossification = laying down of minerals
Bones are formed from ossification of:
Cartilage  Long bones
Membranes  Flat bones
Tendons  Sesamoid bone

17. Development of a Typical Long Bone

18. Bone Growth: Nutrition and Hormones
Vitamin C for collagen synthesis
Vitamin D for normal absorption of Ca from the intestine
Growth hormone for bone growth and development
Thyroid hormone also influences bone and cartilage growth
Sex hormones (oestrogen and testosterone) influence bone growth and account for growth spurt at puberty

19. Growth Hormone

20. Effect of Growth Hormone
Excess GH secretion in children  Gigantism
(Maintain normal body proportions)
Excess GH secretion in adults after the epiphyseal discs are sealed  Acromegaly  No increase in height but Growth of soft tissue  Elongation of jaw, deformities in hands, feet, and bones of face
Inadequate secretion of GH during childhood  short stature

21. Acromegaly

22. Calcium regulation and homeostasis
High blood Ca 
Thyroid gland 
Calcitonin 
Inhibits osteoclast activity 
Bone breakdown inhibited 
Lowers blood Ca
Low blood Ca 
Parathyroid glands 
Parathyroid hormone 
Stimulates osteoclast activity 
Mobilization of Ca from bone 
Raises blood Ca

23. Bones Identify on the model of the skeleton the following bones:
Cranium, clavicle, sternum, ribs, humerus, radius, ulna, carpals, metacarpals, phalanges, pelvis, femur, patella, tibia, fibula, tarsals, metatarsals, phalanges, cervical vertebrae, scapula, thoracic vertebrae, lumbar vertebrae, sacrum, coccyx, calcaneus