1. Supportive text for this material is in Kardong pgs.
Skeletal System
Supportive text for this material is in Kardong pgs.
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You will be responsible for this content… make sure you know the vocabulary

2. Skeletal System Functions: Support Protection Movement Storage
Blood cell production
What types of animals DON’T have osseous skeletons?
List some examples of organs protected…
Do all movements rely on skeletal system?
What types of elements are most likely stored in bone?
What does the skeletal system have to do with blood cells?

3. What components comprise the skeletal system?
Bones
Cartilage
Ligaments
Tendons
Are bones dead?

4. How does cartilage relate to the skeletal system?!?
Origin, growth and repair depend on hyaline cartilage!
Chondroblasts Chondrocytes
Lacunae Perichondrium
Fibroblasts Blood vessels

5. Mary, Mary quite contrary how does your cartilage grow?!?
Appositional growth
Cartilage growth occurs in 2 regions…
1) Periphery via perichondrial cell division and matrix deposition
Interstitial growth
2) Internally via chondrocyte division and matrix deposition

6. Discuss with your neighbor and predict an answer.
Take 5!!!
Explain why damaged cartilage takes a long time to heal. Why doesn’t articular cartilage have a perichondrium, blood vessels, or nerves?
Discuss with your neighbor and predict an answer.

7. What are the anatomical structures of long bones?
Consist of 2 primary regions
Epiphyses
Diaphysis
The ends of longs bones, primarily cancellous bone
The shaft of long bones, primarily compact bone

8. What are the anatomical structures of long bones?
Cartilage (hyaline) plate between 2 regions plays special role!!!
Epiphyseal plate
The cartilage grows and becomes osseous tissue.
Why wouldn’t you want growth here as an adult?

9. What are the anatomical structures of long bones?
What is a good term for the membrane “around” the “bone” ?
Periosteum
2 layers, contains blood vessels & nerves
Endosteum
Single layer of cells lining medullary cavity and cancellous spaces

10. What are the anatomical structures of long bones?
Marrow
Types: Red
Yellow
Distribution: Flat bones
Long bones
Site of blood cell formation
Mostly lipids, energy storage
Location of red marrow
Location of yellow marrow

11. What are the anatomical features of flat, short and irregular bones?
“Cancellous sandwich” no “dia” or “epi” physes
Short
Would you expect diaphysis?
Irregular
No diaphysis, small epiphyses possible

12. What are the histological features of bone?
Looking at this tissue… it is mostly matrix
Mostly (65%) inorganic Hydroxyapatite ~ Ca10(PO4)6(OH)2
Organics are collagen and proteoglycans (35%)

13. A B What are the histological features of bone?
Of the 2 components: fibers (=1) vs. Crystals (=2) Which type are missing from these bone A?
Which type are missing from B?
Normal long bone A
No collagen
No minerals B

14. What are the histological features of bone?
Types of bone cells:
(Most likely to have “osteo”)
Osteogenic
Cells from endosteum and inner periosteum
Osteoblasts
Cells forming matrix
Osteocytes
Cells “trapped” in matrix
Osteoclasts
Multinucleated cells “remodel” matrix
Stem Cells Osteochondral progenitor cells

15. What are the other categories of bone besides the shapes (ex
What are the other categories of bone besides the shapes (ex. Long, irregular etc.)?
Bone is classified depending on the arrangement of cells and matrix.
Types:
Woven ~ Collagen fibers are randomly arranged
Lamellar ~ Collagen fibers are arranged parallel

16. What are the other categories of bone besides the shapes (ex
What are the other categories of bone besides the shapes (ex. Long, irregular etc.)?
Types:
Cancellous (spongy) ~ Network of mineralized bone (Trabeculae) with many spaces
~ Marrow fills up these spaces in life

17. Types:
Cancellous (spongy)
Referring back to our discussion of striae and collagen fibers, what direction do you suppose the trabeculae align in relation to stress?

18. What are the other categories of bone besides the shapes (ex
What are the other categories of bone besides the shapes (ex. Long, irregular etc.)?
Types:
Compact ~ Dense lamellar bone that is mineralized (mature) with numerous units (osteons) arranged around blood vessels
Compare this photomicrograph to the diagram and locate the listed structures

19. Discuss with your neighbor and predict an answer.
Take 5!!!
Compact bone has a specialized canal system for the transport of nutrients and waste products. Why isn’t such a system necessary in cancellous bone? Why not hyaline cartilage?
Discuss with your neighbor and predict an answer.

20. 2 patterns of ossification: Intramembranously Endochondrally
How does your bone grow?
2 patterns of ossification:
Intramembranously
Endochondrally
Originally connective tissue membrane
Originally cartilage that is ossified
Note: Both types start as woven bone, which is remodeled as it matures into lamellar bone

21. How does your bone grow? Intramembranous Ossification
fontanels
How does your bone grow?
Intramembranous Ossification
Occurs during fetal development and “finishes” by 2 years of age
Woven bone fibers connect and thicken forming trabeculae (cancellous bone)
Outer layer of osteoblasts create outer layer of compact bone

22. How does your bone grow? Endochondral Ossification
Occurs during fetal development and “finishes” by “20-something”
Hyaline cartilage model formed
Presence of blood vessels on periphery stimulates osteochondral progenitor cells to become “osteos” rather than “chondros”
Internal chondrocytes die and are replaced by vessels and osteo cells

23. How does your bone grow? Endochondral Ossification
Hyaline cartilage model formed… everything is “chondro”
Blood vessels invading perichondrium stimulate osteogenic cells to become osteoblasts
Perichondrium now becomes periosteum
New osteoblasts form bone collar

24. How does your bone grow?
Buds of connective tissue from periosteum invade cartilage model. Bring in osteogenic cells.
Then what happens?
Osteoblasts form bone as medullary cavity enlarges
Bone growth progresses towards the ends medullary cavity enlarges

25. How does your bone grow?
Osteoblasts form bone in Secondary ossification center, beginning of epiphysis

26. How does your bone grow?
When bone is mature epiphyseal plate is ossified and becomes epiphyseal line

27. Discuss with your neighbor and predict an answer.
Take 5!!!
During endochondral ossification, calcification of cartilage results in the death of chondrocytes. Later in the process, ossification of the bone matrix does not result in the death of osteocytes. Why is this so?
Discuss with your neighbor and predict an answer.

28. Can bone display interstitial growth?
How does your bone grow?
Can bone display interstitial growth?
We’ve talked about bone growth in length… what about diameter?
Appositional deposition and resorption

29. How does your bone grow?

30. How does your bone grow? Factors affecting bone growth:
Nutrition Proteins Vitamins D & C
Hormones Growth hormone Thyroid hormone Sex hormones
Needed for organic portion of matrix
Needed for Ca absorption and Collagen formation
Stimulates overall growth
Stimulates bone growth and works with GH
Stimulates bone growth BUT also closure of epiphyseal plate

31. How does the Skeletal System regulate Ca & P?
Ca and P homeostasis
Calcium: needed for nerve cell action, muscle contraction, blood clotting and more
Phosphorus: needed as a component of ATP, DNA and RNA
Why are these elements important?

32. How does the Skeletal System regulate Ca & P?
Ca and P homeostasis regulated in part via 2 hormones:
PTH (parathyroid hormone) comes from parathyroid glands
Calcitonin minor role… secreted by thyroid gland

33. How does the Skeletal System regulate Ca & P?
PTH +PTH = +blood Ca
via bone, intestine and kidney activities
Calcitonin minor role… +Calcitonin = -blood Ca
Which “osteo” cells do you suppose this hormone stimulates to cause a reduction in blood Ca levels?