Lecture Notes: Bone Structure and Function

Functions of Bones

• Support and Protection
  • Support: Holds the trunk above the ground.
  • Protection: Skull protects the brain; ribs protect the lungs.
• Locomotion
  • Muscles attached to bones help in movement (locomotion).
• Calcium Storage
  • Bones store calcium necessary for blood and bodily functions (e.g., nerve impulse, heart contractions).
• Fat Storage and Blood Cell Production
  • Yellow marrow stores fat.
  • Red marrow (e.g., in hip bone) produces blood cells.

Bone Anatomy

• Blood Supply
  • Excellent blood supply allows nutrient delivery and remodeling.
• Periosteum
  • Membrane covering bones, aids in healing and blood vessel guidance.

Bone Composition

• Cells
  • Osteoblasts: Immature cells that build bone by secreting extracellular matrix.
  • Osteocytes: Mature cells maintaining bone tissue.
  • Osteoclasts: Cells that break down bone, releasing calcium into the blood.
• Extracellular Matrix
  • Contains collagen fibers (flexibility and resistance to stretching) and inorganic salts (calcium for hardness).

Bone Types

• Compact Bone
  • Dense, strong, smooth appearance.
  • Found in diaphysis (middle section) of long bones.
• Spongy Bone (Trabecular Bone)
  • Light, strong, porous structure.
  • Found in the ends of long bones (epiphyses).
  • Comparable to the Eiffel Tower's structure for strength and lightness.

Bone Growth and Structure

• Long Bone Anatomy
  • Diaphysis: Long middle section.
  • Epiphyses: Ends of the bone.
  • Metaphysis: Contains the epiphyseal plate, an area for bone growth in length.

Microstructure of Bone

• Osteon
  • Smallest functional unit of bone.
  • Comprised of spirally arranged collagen fibers and calcium salts.
  • Osteocytes reside in lacunae, with canaliculi connecting them.
  • Haversian Canal: Central canal within the osteon housing blood vessels.
  • Volkmann's Canals: Connect osteons, facilitating communication and nutrient exchange.

Health and Maintenance

• Bone Health
  • Building a good calcium reservoir during growth is essential to prevent osteoporosis.
  • Diet: Limit sodas and hamburgers; consume green leafy vegetables for calcium.
  • Exercise: Engage in weight-bearing exercises like walking or hiking to strengthen bones.