1. Bones
H.Smith

2. BoneTissue
Question…are bones alive?

3. Bones are tissues Tissues are made up of…
There are 4 types of bone cells
Osteo means..

4. 1. Osteoblasts
Found within bones
Function: make new bone tissue

5. 2. Osteocytes Made by Osteoblasts; mature bone cells
Surrounded by bone as they are made
Function: maintain bone as a living tissue

6. 3. Osteoclasts Formed in the bone marrow (Related to WBC)
Function: Dissolve & absorb old bone tissue

7. 4. Hematopoietic
Found in bone marrow
Function: produce blood cells

9. Bone maintenance Bone is constantly being broken down & rebuilt.
What cells break it down?
What cells rebuild it?

11. Bone tissue organization

12. Compact Bone Found on the outside of bones Composed of osteons
Covered by the periosteum: membrane that acts as attachment points for muscles.

13. Closer look at Osteons; AKA Haversian system
Central tube: nerves & blood supply
Lamellae: rings made of calcium & collagen (provide hardness!)
Lacunae: small spaces between lamellae
Home of osteocytes
Canaliculi
Tiny channels between lacunae, function to allow nutrients to the osteocytes & wastes to leave them

14. Compact bone & osteons

17. Now You Practice

18. Lets review:
4 types of bone cells:

19. Let’s review
How is bone maintained?

20. Let’s review: Compact bone is found…. Compact bone is made up of….
Compact bone is covered by…

21. Let’s review:
4 parts of an osteon

22. Inside compact bone is…Spongy bone

23. Spongy Bone Provides strength to weight bearing bones
Protects the bone marrow (hematopoietic cells)

25. Function of Bones Support
Bones provide a hard framework that supports the body
Bones provide support for internal organs

26. Function of Bone Protection Skull protects the brain
Spinal cord is surrounded by vertebrae
Rib cage protects vital organs

27. Function of Bone Movement
Skeletal muscle attached to bones use the bones as levers to move the body
Arrangement of bones and joints determine the movements possible

28. Function of Bones Mineral Storage Bone serves as a mineral reservoir
Phosphate and calcium ions can be released into the blood steam for distribution
Deposition and removal are ongoing

29. Function of Bones Blood cell formation
Hematopoiesis occurs within the marrow cavities of the long bones
The majority of hematopoiesis occurs in bones

30. Ossification
Cartilage is covered by bone & internal hyaline cartilage is broken down

31. Epiphyseal Plates
Site of bone growth in length

32. Bone Growth Through Adolescence
Controlled by growth hormone, and after puberty, sex hormones
Longitudinal growth – occurs at epiphyseal plates
Completely ossified by end of adolescence

33. Bone Remodeling
Constant osteoblast & osteoclast activity throughout life
Causes:
Ca+2 levels in blood
If too low, parathyroid hormone activates osteoclasts
If higher than needed, calcitonin (a hormone) activates osteoblasts
Pull of gravity & muscles
Activates osteoblasts
If not active, activates osteoclasts – atrophy
Partial reason for some bed-ridden individuals

34. Fractures Reduction – realignment of bone ends AKA “resetting”
4 Stages of healing

35. Bone Healing 1. Fracture hematoma
– blood from broken vessels forms a clot.
– 6-8 hours after injury
– swelling and inflammation

36. 2. Fibrocartilaginous callus
lasts about 3 weeks
-Chondroblasts create a cartilage callus around the fracture

37. 3. Bony callus (after 3 weeks and lasts about 3-4 months)
– osteoblasts replace cartilage with bone

38. 4. Bone Remodeling
Osteoclasts remodel bone into compact bone and spongy bone
– Often no trace of fracture line on X-rays.

39. Cool facts about bone breaks:
Your body is so good at healing broken bones, it can be impossible to detect a fracture line after a full recovery.
Collarbone is most commonly broken among children.
Overall most common break is the wrist (before 75 years of age) and the hip (after 75 years of age)

41. Common Types of Fractures

42. Review Which cell type forms new bone? Which cell type destroys bone?
Which cell type is a mature bone cell?
What is the name of the “space” that a mature bone cell is enclosed within?
What kind of tissue are fetal bones made of?
What is ossification?
What is the site of longitudinal bone growth called?

43. Which hormones control bone growth through adolescence?
Which hormones control bone remodeling? What does each one do?
If a doctor reduces a fracture, what is she doing?