1. Bone Composition
Compact Bone
Spongy Bone
Medullary Cavity

2. Bone Composition Articulating Cartilage Periosteum Endosteum
located at both end of a long bone
Allows smooth movement within joints while protecting the ends of the bones
Periosteum
Outer connective tissue that covers the entire length of the bone
Unites with tendons and ligaments at origin and insertion points
Endosteum
Inner connective tissue lining the Medullary Cavity
Medullary cavity
Inside diaphysis
Filled with red & yellow marrow
Red marrow is where blood cell formation occurs
Yellow marrow is composition of adipose cells and connective tissue

3. Bone Composition Calcium carbonate and calcium phosphate: Collagen:
Make up 60-70% of bone weight
Provide much of the bone’s stiffness and resistance to pressing or squeezing forces
Collagen:
Gives bone its characteristic flexibility and contributes to its ability to resist pulling and stretching forces
With aging, collagen is lost progressively and bone becomes more brittle.
Water
Bone consists of much smaller proportion of water than other body parts

4. Bone Classification
According to the degree of porosity, bone can be classified into two general categories:
Cortical or Compact bone (low porosity)
Spongy or Cancellous bone (high porosity)

5. Spongy/ Cancellous Bone
Cortical/Compact Bone
Porosity
High (Low mineral content and high collagen)
Low (High mineral content and low collagen)
Structure
Honey comb
Compact
Characteristic
Provides more flexibility but is not as stress resistant
Stiffer and can resist greater stress but less flexible
Function
Shock absorption due to its better ability to change shape
Withstanding stress in body areas that are subject to higher impact loads
Location
e.g., vertebrae
Long bones (e.g., bones of the arms and legs)

6. How does exercise affect our bones?

7. Affect of Fitness on Bone
When bones are subjected to regular physical activity and habitual loads, they tend to become denser and more mineralized
e.g. Right forearm of a right-handed tennis player is more dense than their left forearm due to more frequent and consistent use.
Inactivity works in the opposite direction, leading to a decrease in weight and strength.
e.g. Loss of bone mass has been noted in bed-ridden patients, inactive senior citizens, and astronauts