1. ©Thompson Educational Publishing, Inc. 2003. All material is copyright protected. It is illegal to copy any of this material. This material may be used only in a course of study in which Exercise Science: An Introduction to Health and Physical Education (Temertzoglou/Challen) is the required textbook. Bone Formation and Remodelling  Ossification (bone formation ) takes two forms:  Compact bone (begins as cartilage):  Osteoblasts discharge osteoid into which minerals are deposited to form the hardened material recognized as bone  Cancellous bone (begins as fibrous membranes):  Osteoblasts release osteoid into membrane which forms a sponge-like bundle of fibres  Cancellous bone formation develops outward from these centres in the membrane  Bone remodelling has two main phases:  Osteoclasts release acids and enzymes to remove old bone  Osteoblasts deposit new tissue *** Two Major Types*** 1.Osteoclasts – tear down 2.Osteoblasts – build up bone matrix

2. ©Thompson Educational Publishing, Inc. 2003. All material is copyright protected. It is illegal to copy any of this material. This material may be used only in a course of study in which Exercise Science: An Introduction to Health and Physical Education (Temertzoglou/Challen) is the required textbook. Epiphyseal Plates and Lines  Epiphyseal plates (growth plates)  Occur at various locations at the epiphyses of long bones  Growth possible  Epiphyseal lines  Occur when epiphyseal plates have fused or come together  Growth not possible Epiphyseal plate Epiphyseal line *** Primary Ossification Centers*** -During fetal development -Form Diaphysis ***Secondary Ossification Centers*** -After birth -Form epiphysis When a child reaches skeletal maturity, @ 18-25 years, all of the cartilage is replaced by bone. Diaphysis and Epiphysis have fused together, plate forms.

3. ©Thompson Educational Publishing, Inc. 2003. All material is copyright protected. It is illegal to copy any of this material. This material may be used only in a course of study in which Exercise Science: An Introduction to Health and Physical Education (Temertzoglou/Challen) is the required textbook. Types of Fractures  Stress fracture – most difficult to detect  Simple fracture – no separation (hairline fracture)  Compound fracture – bone breaks into separate pieces  Comminuted fracture – bone shatters into many pieces Simple fracture Compound fracture Comminuted fracture Stress Fractures – are common among athletes -occur when muscles become too fatigued to absorb the shock placed on them Simple Fractures – no bone separation - break/crack still detectable Compound Fractures – “transverse fractures” -bone breaks into separate pieces -usually the result of a major blow Comminuted Fractures – the broken end of the bone has been shattered into many pieces - usually the result of a car accident or crash

4. ©Thompson Educational Publishing, Inc. 2003. All material is copyright protected. It is illegal to copy any of this material. This material may be used only in a course of study in which Exercise Science: An Introduction to Health and Physical Education (Temertzoglou/Challen) is the required textbook. Effects of Aging – Skeletal System  Remodelling declines from fourth decade onward  Process of bone remodelling reverses – resorption occurs  Results in a 5–0% loss in bone mass per subsequent decade  Affects overall calcium levels in the body  Osteoporosis (low bone mass and deterioration of the bone tissue) may result from resorption  Leads to bone fragility  Increased susceptibility to bone fractures  Preventative measures include:  Balanced diet rich in calcium and vitamin D, and a healthy lifestyle  Weight-bearing exercises  Bone density testing and medication when appropriate