1. Anatomy and Physiology I Unit 7: The Skeletal System
Physiology of the Skeletal System

2. Skeletal System Bones are made of several tissues
Primarily made of collagen and hydroxyapatite - Ca10(PO4)6(OH)2
About 206 bones in the human body

3. Functions of Skeletal System
SUPPORT: Hard framework that supports and anchors the soft organs of the body.
PROTECTION: Surrounds organs such as the brain and spinal cord.
MOVEMENT: Allows for muscle attachment therefore the bones are used as levers.
STORAGE: Minerals and lipids are stored within bone material.
BLOOD CELL FORMATION: The bone marrow is responsible for blood cell production.

4. Parts of the Skeletal System
Axial skeleton
Skull and bones that support it
Includes vertebra and ribs
80 bones
Appendicular skeleton
Limbs
126 bones

5. Epiphysis: Ends of the bone.
Features of a Long Bone:
Epiphysis: Ends of the bone.
Diaphysis: The shaft of the bone which surrounds the medullary cavity.
Articular Cartilage: Cushions the ends of the bones and allows for smooth movement.
Epiphyseal Plate:
Areas made of cartilage allowing for the growth of the bone.

6. Joints Where bone meets bone Ligament – holds bone to bone
Types of joints:
Immovable - skull
Ball-and-socket - shoulder
Hinge - knee
Pivot – forearm
Gliding - vertebrae

7. Joints Cartilage covers ends of movable bones
Reduces friction
Lubricated by fluid from capillaries

8. Cartilage

9. Bone Structure Periosteum – hard outer covering
Cells for growth and repair
Compact bone – hard strong layer
Bone cells, blood vessels, protein with Ca and P
Spongy bone – at ends of long bones
Has small open spaces to lighten weight
Marrow cavity – hollow in middle of long bones

10. Bone Marrow Red marrow – produces blood cells and clotting factors
Found in humerus, femur, sternum, ribs, vertebrae, pelvis
Produces RBC 2 million per second
Yellow marrow – stores fat
Found in many bones

11. Bone Structure

12. Haversian System Structure of compact bone
Rings of bone tissue with blood vessels and nerves in the center

13. Haversian System

14. Bone Development Initial skeleton of cartilage in infants
Replaced with bone by osteoblasts
More than 300 bones at birth – fuse to 206
Always growing and breaking down
Osteoblasts – form new bone cells
Osteoclasts – break bone cells down
Osteocytes – mature bone cells

15. Broken Bones Fracture is a break of the bone
Simple or Complex fracture
Regrowth of bone:
Spongy bone forms in first few days
Blood vessels regrow and spongy bone hardens
Full healing takes 1-2 months

16. Rickets Homeostatic Imbalances
Disease of children due to a lack of vitamin D.
Calcium is not deposited in bones.
Bones become soft.
Bowing of the bones, and other deformities occur.

17. Osteomalacia Homeostatic Imbalances “Rickets” of adults.
Due to a lack of vitamin D.
Calcium is not deposited in the bones.
Bones become brittle.

18. Osteoporosis Homeostatic Imbalances
Bone reabsorption is greater than bone deposition.
Due to any of the following:
Lack of estrogen in women.
Lack of exercise to stress the bones.
Inadequate intake of calcium and phosphorus.
Abnormalities of vitamin D metabolism.
Loss of muscle mass.

19. Age Related Dysfunctions
Arthritis:
Osteoarthritis- 90% of pop. By age 40
chronic inflammation of articular cartilage
can be normal age-dependent change
can also be pathology due to ?
Age-related changes
decrease blood supply
trauma

20. Osteoarthritis

21. Osteoporosis Decline in Bone Density
Bone Resorption > Bone Deposition
Increase Risk for Fracture
compression fractures of vertebrae
hip fractures
Role of calcium, vitamin D, estrogen, exercise
Calcitonin vs. Parathyroid Hormone

22. Osteoporosis