Bone Tissue Lecture 1 Flashcards
6 Main Functions of Bone
- Support
- Protection
- Assisstance in movement
- Mineral Homeostasis
- Blood cell production
- Storage of triglycerides
Bone Structure: Diaphysis
Description, Example
Description:
* Main bone shaft, long, tubular,
* Predominantly made of compact bone
* Houses yellow bone marrow.
Bone Structure: Epiphysis
Description, Example
Description:
* Epiphysis: Ends of bones
* Filled with cancellous/spongy bone
* Houses red marrow
* Projections/fossae for articulations.
Bone Structure: Metaphysis
Description, Example
Description:
* Portion between diaphysis and epiphysis
* Weakest portion of bone,
* Contains epiphyseal plate which becomes epiphyseal line.
Bone Structure: Medullary (marrow) Cavity
Description, Example
Description:
* Hollow cavity in the diaphysis
* Contains yellow bone marrow and numerous blood vessels
* Lined with endosteum.
Bone Structure: Endosteum
Description, Example
Description:
* Layer of dense irregular connective tissue that lines the medullary cavity and internal spaces of spongy bone.
Bone Structure: Periosteum
Description, Example
Description:
- “Skin” surrounding bones,
- Made of fibrous and cellular layers.
Bone Structure: Articular (hyaline) cartilage
Description, Example
Description:
- Cartilaginous tissue at the ends of bones (covers epiphysis),
- Reduces friction and allows movement at articulations.
Bone Histology: Extracellular Matrix of Bone
Description, Example
Description:
* Organic component of ECM, including collagen fibers and crystallized mineral salts.
Bone Histology: Ground Substance
Description, Example
Description:
* Inorganic component of ECM, mainly calcium phosphate,
* Provides strength to bone.
Bone Histology: Hydroxyapatite
Description, Example
Description:
* Formed by the interaction of calcium phosphate and calcium hydroxide,
* Providing the structural rigidity of bone.
Bone Histology: Osteoprogenitor (osteogenic) Cells
Description, Example
Description:
- Unsophisticated stem cells derived from mesenchyme tissue
- Capable of mitosis
- Develop into osteoblasts.
Osteoblasts
Description, Example
Description:
* Bone-building cells,
* Secrete collagen and bone matrix proteins to form osteoid
* Initiate calcification.
Bone Histology: Osteocytes
Description, Example
Description:
- Mature bone cells that maintain and monitor metabolic activities
- Connected by canaliculi and occupy lacunae.
Bone Histology: Osteoclasts
Description, Examples
Description:
- Bone cells that break down bone tissue in a process called resorption.
- Taking calcium from the bone into the bloodstream.
- Found on the bone surface, and active osteoclasts are located in Howship’s lacunae.
Types of Bone Tissue: Compact Bone
Description, Example
Description:
- Hard and dense bone tissue, with little or no spaces between cells
- Strongest form of bone
Types of Bone Tissue: Compact Bone
Osteons
Description, Example
Description:
- Individual structural units of compact bone,
- Consisting of concentric lamellae surrounding a Haversian canal.
Types of Bone Tissue: Compact Bone
Interstitial Lamellae
Description, Example
Description:
Lamellae located between osteons, filling spaces not occupied by osteons.
Types of Bone Tissue: Compact Bone
Circumferential Lamellae
Description, Example
Description: Lamellae surrounding the medullary cavity or lying underneath the periosteum.
Types of Bone Tissue: Compact Bone
Haversian (Central) Canals
Description, Example
Description:
- Parallel canals running longitudinally along the bone shaft
- Conducting blood vessels, lymph vessels, and nerves.
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Types of Bone Tissue: Compact Bone
Volkmann’s Canals
Description, Example
Description:
- Perpendicular canals running superficial to deep
- Conducting blood vessels, lymphatic vessels, and nerves through the periosteum.
Types of Bone Tissue: Compact Bone
Lacunae
Description, Example
Description: Small spaces within lamellae containing osteocytes.
Types of Bone Tissue: Compact Bone
Canaliculi
Description, Example
Description:
- Small channels radiating in all directions from each lacuna
- Filled with fluid and osteocyte filopodia.
Types of Bone Tissue: Spongy Bone
Description, Example
Description:
- Also known as trabecular or cancellous bone,
- Lacks osteons
- Appears spongy due to a lattice and irregular pattern of bone tissue distribution.
Types of Bone Tissue: Spongy Bone
Blood Supply
Description, Example
Description:
- Spongy bone has a greater blood supply than compact bone,
- Producing red blood cells, white blood cells, and platelets.
Types of Bone Tissue: Spongy Bone
Distribution in Bones
Description, Example
Description:
- In long bones, spongy bone is concentrated in the epiphysis,
- In flat bones, it predominates the inner structure.
Types of Bone Tissue: Spongy Bone
Trabeculae
Description, Example
Description: The lamellae of spongy bone are arranged into small struts or beams, resembling a “coral reef” appearance.
Bone Formation: Ossification/Osteogenesis
Description, Example
Description: The process of bone formation begins during the 6th week of embryonic development.
Bone Formation: Endochondral Ossification
Description, Example
Description: processwhere initial skeleton of the embryo is made of hyaline cartilage, which is replaced by bone.
Hyaline cartilage into bone
Bone Formation: Intramembranous Ossification
Description:
- Involves the replacement of sheet-like connective tissue membranes with bony tissue.
- Stem cells become osteoblasts in connective tissue, forming dermal/membrane bones.
Primary/Secondary Ossicication Centers
Primary Ossification Centers: Appear during prenatal development in the central part of each developing bone.
Secondary Ossification Centers: Develop in the epiphyseal region after birth.
Intramembranous Ossification:
Dermal/Membrane Bone Formation:
Stem cells become osteoblasts in connective tissue, forming dermal/membrane bones.
Growth in length (interstitial growth)
Epiphyseal plate
- Hyaline cartilage in metaphysis becomes site for new bone.
- After maturity, it turns into epiphyseal line.
Interstitial growth
Resting Cartilage Zone
- Nearest to epiphysis
- Small chondrocytes anchor plate to epiphysis
Interstitial Growth
Proliferating Cartilage Zone
- Large chondroblasts replicate and divide
- Appears like stacks of coins
Interstitial Growth
Hypertrophic Cartilage Zone
Large, mature chondrocytes in columns
Interstitial Growth
Calcified Cartilage Zone
- Mostly dead chondrocytes; area calcified
- Osteoblasts invade to lay down new matrix; diaphysis conversion
- Growth in length (interstitial growth)
Growth in thickness (appositional growth)
- Osteogenic cells differentiate into osteoblasts under the periosteum to add bone matrix
- Osteoclasts remove matrix at inner surface to enlarge medullary cavity
