1. Structure and Function
Bones
Structure and Function

2. Skeletal System Organization
System = Skeletal
Organs = Bones
Each bone is an individual organ
Work together as joints (considered later)
Tissues = Connective
Compact Bone
Spongy (cancellous) Bone
Hyaline Cartilage

3. Skeletal System – Macroscopic Anatomy
Axial Skeleton
Head
Vertebrae
Ribs
Pelvic Girdle
Appendicular Skeleton
Arms
Legs

4. We will use long bones as our example.
Bone Types
We will use long bones as our example.

5. Long Bone – Macroscopic Anatomy
Epiphysis (end)
covered with hyaline cartilage
compact bone forms exterior
spongy bone forms interior
contains epiphyseal line/plate
Diaphysis (middle)
center composed of the medullary cavity containing yellow or red marrow
Fig 7.1

6. Long Bone – Macroscopic Anatomy
Fig 7.2

7. Long Bone – Microscopic Anatomy
Osteon = circular structure organized around blood vessels
Osteocyte = bone cells
Bone matrix = hard calcium-based material between cells
Fig 7.3

8. Specialized Connective Tissue Connective Tissue Proper
Bone – Tissue Types
Bones and joints are composed primarily of connective tissue
Connective tissue is organized by type of extracellular matrix
Connective Tissue
Specialized Connective Tissue
Bone
Spongy Bone
Compact bone
Blood
Cartilage
Hyaline
Elastic
Fibro
Connective Tissue Proper
Loose
Reticular
Adipose
Areolar
Dense

9. Tissue Types – Compact Bone
Functions
Hard and provides stability, framework, protection
Structure
Matrix has hard mineral structure, based on calcium
Cells and matrix are arranged in regular, concentric pattern
Compact Bone

10. Tissue Types – Spongy Bone
Functions
Lightens total bone weight and provides space for bone marrow
Structure
Matrix is softer mineral, less organized and less of it
Empty spaces between matrix structure are filled with bone marrow
Spongy (cancellous) Bone

11. Tissue Types – Hyaline Cartilage
Functions
Provides soft and smooth covering to end of bone (articular surface)
Helps provide smooth and easy movement between bones (at joints)
Provides the starting material for new bone growth
Structure
Matrix is spongy (like jello) and evenly distributed between the cells
Cells (chrondocytes) are found in pairs within capsules called lacunae
Hyaline Cartilage

12. Bone Physiology Living bones perform the following processes:
Formation
Starts as an embryo, continues through fetal development and after birth
Growth
Occurs from before birth through maturity
Remodel
Old matrix is removed and replaced with new matrix
Repair
Damaged bones will heal and return to normal structure

13. Bone Physiology – Formation
Fetal bones are made of hyaline cartilage
As cartilage cells die, they are replaced with spongy bone in diaphysis
After birth, spongy bone invades diaphysis
Compact bone replaces spongy bone in diaphysis
Hyaline cartilage remains on epiphyseal surface and in growth plate
Fig 7.5

14. Bone Physiology – Growth
Bones grow in length at the epiphyseal plate – hyaline cartilage in the epiphysis
Cartilage cells divide causing the epiphyseal plate (and bone) to grow
Cartilage cells die and are replaced by spongy bone
As adolescence ends, the growth plate decreases in size and eventually is replaced by bone
bone growth video

15. Bone Physiology – Growth
Epiphyseal (Growth) Plate

16. Bone Physiology – Growth

17. Bone Anatomy and Physiology Lab – 2A17

18. Bone Anatomy and Physiology Lab – 2A
Cow = more compact bone; less hyaline cartilage; no active growth plate (bone not cartilage); yellow marrow
Calf = less compact bone; more hyaline cartilage; active growth plate (cartilage, not bone); red marrow 18

19. Bone Physiology - Repair
Hemotoma, a mass of clotted blood, forms at the fracture site.
A fibrous callus forms, and cartilage matrix is secreted.
Spongy bone forms to replace cartilage.
Bone remodeling occurs to remove excess material and replace compact bone.

20. Bone Physiology - Remodeling
Bone matrix is inorganic and breaks down over time
Specific bone cells (osteoclasts) remove old, broken matrix
Other bone cells (osteoblasts) re-make/deposit new matrix
The entire skeleton is re-modeled every 7-10 years
Remodeling slows with age, elderly people have thinner bones and are more susceptible to broken bones as a result