Understanding Bone Microscopic Structure

Oct 7, 2024

Lecture Notes: Microscopic Structure of Bones

Introduction

  • Discussion: Microscopic structure of bones
  • Previous video: Introduction to the skeletal system
  • Important Cells:
    • Osteocytes: Main bone cells
    • Osteoblasts: Build bone
    • Osteoclasts: Cut down bone (similar origin to macrophages)

Bone Composition

  • Matrix: Consists of Type 1 Collagen
  • Minerals: Primarily calcium (forms hydroxyapatite crystals)
  • Collagen: Starts as pre-pro-collagen, becomes pro-collagen, then collagen
    • Post-translational modification is crucial
    • Disruption leads to diseases (pathology)

Haversian System

  • Bone Layers: Known as lamellae
  • Osteons: Organized structure of matrix and minerals
    • Haversian Canal: Longitudinal, contains blood vessels
    • Volkmann's Canal: Horizontal, connects Haversian canals
  • Lacunae: Houses osteocytes
  • Canaliculi: Small canals connecting lacunae

Bone Nourishment

  • Bones are vascular (unlike cartilage)
    • Contains blood, lymph vessels, and nerves

Vitamin D and Calcium Homeostasis

  • Essential for calcium regulation
  • Active form requires:
    • Sunlight
    • Liver
    • Gut
    • Skin
    • Kidney
  • Process:
    • Liver and skin add hydroxyl groups
    • Kidney produces 1,25-dihydroxyvitamin D (calcitriol)

Parathyroid Hormone (PTH) and Calcitonin

  • PTH: Raises calcium in blood, lowers phosphate
    • Acts on gut, bone, kidney
  • Calcitonin: Lowers calcium and phosphate
  • Vitamin D: Increases both calcium and phosphate

Bone Remodeling

  • Continuous process involving osteoclasts and osteoblasts
  • Affected by hormones and mineral balance

Additional Information

  • Mention of online courses related to medicine and physiology
  • Encouragement to subscribe and engage with content