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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
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