1. Welcome to Unit 5!
The Skeletal System

2. Subdivisions The skeletal system is subdivided into two divisions
Axial skeleton
Bones that form the longitudinal axis of the body
Skull, vertebral column, pelvis
Appendicular skeleton
Think appendages
Bones of limbs
The system includes
Bones (206 of them in adulthood!)
Joints
Cartilages
Ligaments

3. Functions Predict first! Functions Your book found 5 functions Support
Protection
Movement
Storage
Blood cell formation

4. Classification Classification of Bones Question: Compact bone
Dense, smooth, on the outside of the bone
Spongy bone
Small, needle-like pieces of bone and lots of open spaces
Question:
What might those open spaces be helpful?
Lighten the load!

5. Warm Up
Predict: What would happen if there was too much compact bone?

6. Melorheostosis
Causes excessive growth of compact bone

7. Classification Classification based on shape Long bones Short bones
Flat bones
Irregular bones

8. Classification Description Examples
Long bones
Longer than they are wide
Mostly compact bone
Femur, radius, ulna, tibia, humerus
Short bones
Cube-shaped
Contain mostly spongy bone
Wrist and ankle bones
Patella
Flat bones
Thin, flatted, and generally curved
2 thin layers of compact bone sandwiching a spongy bone
Usually protect vital organs
Skull, ribs, sternum
Irregular bones
Catch-all category
Needed for muscular attachment and protection
Vertebrae and hip bones
Activity: present some notes and have them categorize them?

9. STOP! Color the different bone shapes
Draw a SQUARE around the axial skeleton and label it
Draw CIRCLES around the appendicular skeleton and label it
Make a table on the back with a drawing of a cross-section of long/short/flat bones that shows the compact/spongy bone

10. Structure of Long Bones-Outside
Diaphysis: shaft, composed of compact bone
Epiphysis: ends of the long bone
Consists of a thin layer of compact bone enclosing an area of spongy bone
Epiphyseal line: demarcation between diaphysis and epiphysis
This is where your growth plate used to be

11. Growth Plate
u.edu/staff/m/b/mbt102/ bisci4online/bone/bone5 .htm
More on this later 

12. Structure of Long Bones-Outside
Articular cartilage: hyaline cartilage that covers the epiphysis and provides a smooth, slippery surface for smooth joint movement
Periosteum: fibrous connective tissue membrane that covers and protects the diaphysis

13. Structure of Long Bones-Inside
Inside the diaphysis, there is a medullary cavity
Called “yellow marrow”
Stores fat
Question:
Why might it be advantageous for the bones to be this way?
Again, lighten the load!

14. Structure of Long Bones-Inside
In infants, the medullary cavity used to house “red marrow’
Site of blood cell formation
Marrow makes white blood cells (WBC), red blood cells (RBC), and other components
In adults, blood cell formation is confined to spongy bone of flat bones and a few long bones

15. Leukemia http://www.youtube.com/watch?v=HP4NxUFgFrs
Leuko (white) + emia (condition of the blood) = condition of the white blood cells
Cancer of the blood cells that originates in the bone marrow
Makes abnormal white blood cells that grow out of control
Diagnosed through a bone marrow biopsy
Treatment
Chemotherapy
Bone marrow transplant

16. Note: The surface of each bone is full of bony markings
Where muscles, tendons, ligaments attach
Where blood vessels and nerves pass
We will be getting into this stuff after we learn more about the physiology of the bones so get excited!!! (This is the best part!)

17. Microscopic Anatomy-Compact Bone
Has many passageways for nerves, blood vessels and route for waste disposal

18. Bone Formation, Growth, and Remodeling