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
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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
Epiphyseal
line
 Growth possible
 Epiphyseal lines
 Occur when epiphyseal plates have fused or come together
 Growth not possible
*** Primary Ossification Centers***
-During fetal development
-Form Diaphysis
***Secondary Ossification Centers***
-After birth
-Form epiphysis
Epiphyseal
plate
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.
©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
©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
©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.