Bone Growth in length and width ex 5 lab

Sep 15, 2024

Lecture on Bone Growth and Remodeling

Overview

  • Bone growth and remodeling: Key concepts in understanding how bones grow in length and thickness.
  • Resource suggestion: Utilize WileyPlus for animations and interactions about bone growth.

Interstitial Growth

  • Definition: Growth in length occurring within cartilage.
  • Location: Takes place in the epiphyseal plate within the metaphysis region.
  • Number of Epiphyseal Plates: Two per bone, a proximal and a distal one.
  • Cartilage Type: Made of hyaline cartilage.

Zones of the Epiphyseal Plate

  1. Zone of Resting Cartilage
    • Located on the epiphyseal side, attached to the epiphysis.
    • Cells are preparing for future growth.
  2. Zone of Proliferating Cartilage
    • Chondrocytes divide rapidly.
  3. Zone of Hypertrophic Cartilage
    • Cells increase in size but lose the ability to divide.
  4. Zone of Calcified Cartilage
    • Chondrocytes die, osteoblasts lay down new bone.
    • Cartilage hardens and is adjacent to the diaphysis.

Bone Growth Influences

  • Hormones: Play a major role in bone growth.
    • Puberty: Significant growth spurts due to increased hormones.
    • Estrogen and Testosterone: Promote osteoblast activity and inhibit osteoclast activity.
    • Human Growth Hormone (HGH): Released from the pituitary gland, affects liver to release IGFs.
    • Insulin-like Growth Factors (IGFs): Stimulate chondrocytes to divide and osteoblasts to lay down bone.

Growth in Width - Appositional Growth

  • Location: Occurs beneath the periosteum and throughout life.
  • Process:
    1. Periosteal ridges form around blood vessels.
    2. Ridges fuse, forming a tunnel.
    3. Enclosed periosteum becomes endosteum.
    4. Osteogenic cells lay down new bone, forming concentric lamella.
  • Result: Formation of new osteons, contributing to compact bone.

Summary of Growth Processes

  • Length Growth: Interstitial growth occurs until approximately ages 18-21.
  • Width Growth: Appositional growth continues throughout life.

Important Considerations

  • Homeostasis: Balance between chondrocyte production and death is crucial for bone growth.
  • Osteons: Form only in compact bone during appositional growth.

Video Resource: A quick video was suggested for summarizing appositional growth steps, emphasizing key processes and structures involved.