1. The Skeletal System
Chapter 45.2

2. The Human Skeleton Has approximately 206 bones! Functions:
Gives Shape and Support
Protection
Moves Muscles
Forms Blood Cells
Stores Minerals- Ex: Calcium and Phosphorus
Bones are moist, living tissues (not dry!)

3. Parts of the Skeleton 2 Parts: Axial- bones of the:
Skull
Ribs
Spine
Sternum
Appendicular- bones of the:
Arms
Legs
Scapula
Clavicle
Pelvis

4. Bone Structure
Periosteum-tough membrane that surrounds the bone’s surface. Contains blood vessels to supply nutrients.
Spongy Bone- network of connective tissue found under the compact bone. Hard/strong tissue. Makes bones light
Marrow: soft tissue in spongy bone
Compact Bone- hard material found under the periosteum. Makes bones strong and capable of enduring large amounts of stress
Red: produces red blood cells, platelets, and white blood cells
Yellow: consists mostly of fat cells and serves as an energy storage

5. Bone Structure
Compact bone is composed of cylinders of mineral crystals and protein fibers called lamellae
In the center of each cylinder is a narrow channel called a Haversian canal
Blood vessels run through interconnected Haversian canals, which carries nutrients throughout the bone
Surrounding each Haversian canal are protein fibers and ostecytes (bone cells)

6. Bone Development Bones develop from cartilage In fetal development:
Connective tissue
Tough, yet flexible
In fetal development:
Month 2: most of the skeleton is cartilage
Month 3: Ossification turns most cartilage into bones
Some cartilage is left for flexible areas between bones
Ex: tip of the nose, outer ear, and inside the trachea
Normal bone development depends on regular exercise and diet, mainly calcium and vitamin D intake
Lack of this can lead to osteoporosis

7. Joints The place where 2 bones meet
Tough bands of connective tissue called ligaments hold the bones of the joint in place
Synovial fluid- a lubricating substance that helps protect the ends of the bones from damage by friction

8. Hinge Joint Found in your elbow
Allows you to move arm forward and backward
Like a hinge in a door

9. Gliding Joint Allows bones to glide over one another
Like small bones in your feet-allows flexing when walking

10. Pivot Joint
Top 2 vertebrae in your neck. Allows you to move your head side to side.

11. Ball and Socket Joint Found in your shoulder or hip
Allows you to move up/down, forward/backward, or rotate in a circle

12. Saddle Joint At the base of your thumb
Allows you to rotate your thumb and grasp objects with your hand

13. Possible injuries and illnesses
Rheumatoid Arthritis-immune system attacks body tissues. Joints become inflamed, swollen, stiff, and deformed
Osteoarthritis- degenerative joint disease where cartilage covering the bones become thin and rough.
Sprain (ligament)- could either overstretch or possibly tear
Strain (tendon)- could either overstretch or possibly tear