HUBS191 - lecture 4

    Cards (26)

    • This pre-lecture material is to help you prepare for the lecture and to assist your note-taking within the lecture, it is NOT a substitute for the lecture
    • Although every effort is made to ensure this pre-lecture material corresponds to the live-lecture there may be differences / additions
    • Bone
      A living tissue with cells and a calcified extracellular matrix
    • Bone cells
      • Respond to external forces
      • Bone remodels and can change shape through your life to reflect how you are using your skeleton
    • Bone can repair itself
    • Extracellular components of bone
      • Organic
      • Inorganic
    • Organic component
      33% of bone ECM, includes collagen and ground substance, functions to resist tension
    • Inorganic component
      67% of bone ECM, includes hydroxyapatite and other mineral salts, makes bone hard and resistant to compression
    • Bone cells
      • Osteogenic cells
      • Osteoblasts
      • Osteocytes
      • Osteoclasts
    • Osteogenic cells
      Stem cells that produce osteoblasts
    • Osteoblasts
      Produce new bone matrix
    • Osteocytes
      Recycle protein and minerals from matrix
    • Osteoclasts
      Remove bone matrix
    • Bone homeostasis
      Balance of bone destruction and formation that means amount of bone stays the same
    • Types of bone tissue
      • Compact
      • Cancellous
    • Compact bone
      Outer surfaces seem dense and impenetrable, made up of circumferential lamellae and units called osteons
    • Osteon
      Longitudinal unit within compact bone, provides a pathway for nutrients to get to cells in the ECM, contains a central canal with blood vessels and nerves, and is formed of a series of cylinders called lamellae
    • Lacunae
      Lakes for osteocytes within the osteon
    • Canaliculi
      Channels for osteocytes through the ECM
    • Cancellous bone
      Contains trabeculae, which are struts of lamella bone with marrow filling the cavities between them
    • Trabecular bone
      • Organisation of trabeculae resists force from multiple directions and directs force from body weight in single direction down shaft, spreading force distally
    • Bone remodelling
      1. Osteoblasts add bone matrix in lamellae to bone surface
      2. Osteoclasts remove bone from the medullary cavity
    • Osteoporosis
      Loss of cortical bone and thinning of cancellous bone trabeculae, leading to compression fractures of vertebrae
    • Biological females are more at risk of osteoporosis due to loss of estrogen post-menopause
    • Lifestyle factors like lack of exercise and nutritional factors can also contribute to osteoporosis risk
    • Peak bone mass in your 20s determines your risk of osteoporosis later in life